EQ International Nov/Dec 2011 : Intersolar India Special Edition

EQ PV Manufacturing Special Section

Issue # 8 | November- December 11

INTERNATIONAL

Solar PV Grid Connected Plants “Case Studies and Plants Reports”

Bidding Outcome-JNNSM Phase 1, Batch II

Extreme Condition for PV in India-The Ultimate Test for Inverters

Renewable Energy Certificates-Status & Way Forward

Come and see us at InterSolar Mumbai - India 14-16 December 2011 Stand 1361 Hall 1

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It’s like having your own sun.

Energy park Lauingen, 25.7 MWp, Germany

Great visions start with simple questions. For example: how can the power of the sun be used to earn money? Gehrlicher, one of the fastest-growing photovoltaic companies, knows the answer: with reliable, efficient and highly profitable solar power plants that achieve peak yields proven by long and unbroken series of data. And that means you also can turn the sun into your own personal source of energy and revenue: www.gehrlicher.com

Visit us at Intersolar India 2011 Bombay Exhibition Centre, Hall 1 - Booth 1936 Gehrlicher Solar India Pvt Ltd • 6th floor, Soham House, Hari Om Nagar • Mulund (E), Mumbai 400 081 Tel. +911122 2598 2070, 6565 7333 • Cell +91 98200 77872 • india@gehrlicher.com 2 EQ INTERNATIONAL November/December Gehrlicher Solar AG • Max-Plank-Str. 3 • 85609 Dornach n. Munich, Germany • info@gehrlicher.com

www.EQMagLive.com

EDITORIAL Is This The Real Cost Of Solar Power ?

A Very aggressive bidding round was seen at the Scope Complex Auditorium for the Batch II of Phase 1 of JNNSM’S 350 MW OF SOLAR PV Projects. French Co. Solar Direct Emerged as Lowest Bidder @ Rs.7.49 per solar KWHR while Green Infra highest bidder @ Rs.9.39 per KWHR. Cost of Solar Power has already beaten the cost of diesel-generated power and the price at which electricity is traded at Indian Energy Exchanges at times. Its exciting to note that solar power could soon hit grid parity for some areas in India atleast.On the flip side the bankability and feasibility of the projects remains a concern.

CERC recently fixed the floor price of solar REC for the period 2012-2017 as Rs.9300 / MWH which makes projects under the REC Mechanism more profitable in the short term. In the long term even if one predicts the Solar REC’s price falling, the expected rise in the price at which electricity could be sold after 2017 would keep projects under REC Mechanism in line with JNNSM projects. It is noteworthy that REC projects have no domestic content mandate, no requirements for bid-bonds, bank guarantees etc thus reducing the burden of financial costs on the cost of solar power.

However REC Mechanism has its own flaws and ambiguity on many aspects.

What is the true cost of Solar Power ? Is this price sustainable in the long run or will the cost fall down more as some predicts the polysilicon prices to come down or will it rise in the future. Is this an artificial price?

The United States Department of Energy estimates that last year alone, the Chinese government provided its manufacturers with over $30 billion in subsidies, including $7 billion alone to one company, Suntech.

SolarWorld Industries America Inc., petitioned the federal government to halt what the company describes as an ever-rising tide of heavily subsidized solar cells and panels that China’s state-supported solar industry is illegally dumping into the American market. According to SolarWorld “China actually has no production cost advantage. Labor makes up a modest share of solar-industry costs, China’s labor is less productive, its raw material and equipment have come from the West and China must pay for long-distance shipping. Yet, massive state subsidies and sponsorship have enabled Chinese manufacturers to illegally dump their products into a wide-open U.S. market.”

Chinese Multinationals like Trina,Suntech,Canadian,Yingli, Jinko etc..have denied the allegations and said that the petition is exaggerated and without merit.

Meanwhile the PV Market worldwide is going through difficult times.

PV Manufacturing Equipment Revenues is predicted to More Than Halve in 2012 According to IMS Research .Senior Research Analyst Tim Dawson comments: “IMS Research estimates that the PV manufacturing equipment market, after a record year in 2011 ($12.8 billion revenues), will be worth just over $5.7 billion in 2012.

Bank Sarasin’s sustainability study on the solar industry: just a few German solar companies will survive the market shakeout.

A shakeout of the solar industry is inevitable as the imbalance between production capacities and demand has become too great with around 50 gigawatts (GW) of production capacity for solar modules compared with sales of 21 GW at the end of this year. The companies best positioned for the next stage of growth in the PV market from 2013 onwards include Suntech Power, Trina Solar and Yingli Solar from China, First Solar and Sunpower from the USA and Solarworld from Germany. The companies under the most threat are mainly small to medium-sized companies with comparatively modest growth prospects, such as Germany’s Conergy, Q-Cells, Solar-Fabrik and Sunways.

With this we Welcome you to India to celebrate Intersolar India in Mumbai December 13-16, 2011 and present our November/December 2011 Issue which talks about PV Manufacturing, Grid Connected PV Plants, Inverters, REC Mechanism, Nanotechnology etc…Hope you enjoy reading the same !!!

Anand Gupta Editor & CEO

VOLUME 1 ISSUE 8

CONTENTS

INTERNATIONAL

FirstSource Energy INDIA PRIVATE LIMITED

17 Shradhanand Marg, Chawani Indore – 452 001 INDIA Tel. + 91 731 255 3881 Fax. +91 731 2553882

Ivan Sinicco

PV MANFUACTURING

PV MANFUACTURING

22

30

www.EQMagLive.com

Advanced Wire Sawing Technology For Solar Photovoltaic Cells

EDITOR & CEO:

A Close Look Into The Role An Encapsulant Can Play In Increasing The Power Of A Thin Film Solar Module

ANAND GUPTA anand.gupta@EQmag.net

PUBLISHING COMPANY DIRECTORS: ANIL GUPTA

ANITA GUPTA

Editorial Department:

ZOHA MAHDI zoha.mahdi@EQmag.net

Editorial Contributions:

Ivan Sinicco, Gaurav Sood, Munjal Rangwala, Vish Palekar, Rakesh Khanna, Balawant Joshi, Navodit Kumar Garg, ROTH & RAU, Meyer Burger, Ravinder Bhardwaj, Barry Ketola, Chris Shirk, Philip Griffith, Gabriela Bunea, LavanderaAntolín, Juan Diego; Cañon- Sanchez, Pamela, Darshan.C.S.- SriVasavi Adhesive, LI yinbai, Rajnikanth Umakanthan, Jurgen Wolfahrt, Thomas Wittek & Nitin Bhosale, Mukund Shendge & Nitin Bhosale, Manish Sharma, Ben Rooke, Alexandre Welferinger, Shaminder Singh Ragi,Avinash Iyer, Vikram Kataria

Gaurav Sood

SOLAR ENERGY 50

Performance of Solairedirect’s First Solar Park: VINON-SUR-VERDON – 4.2MWp

Munjal Rangwala

SOLAR ENERGY 52

Sales & Marketing:

GOURAV GARG gourav.garg@EQmag.net

German Expertise Coupled With Indian Engineering : Receipe for Perfect PV Plant in India

Subscriptions:

PIYUSH MISHRA piyush.mishra@EQmag.net

Advertising Sales North America Office : 4928 Eastlake Drive Apt 16G Murray, UT 84107 United States of America

Layout and Design: MD SUHAIL KHAN

SOLAR ENERGY

SOLAR ENERGY

Publishing:

58

72

ANAND GUPTA

Printer:

PRINTPACK PVT. LTD. 60/1, BABU LABHCHAND CHHAJLANI MARG, INDORE- 452009 (MP) PH. +91-731 2763121 FAX.+91-731 2763120 Disclaimer,Limitations of Liability While every efforts has been made to ensure the high quality and accuracy of EQ international and all our authors research articles with the greatest of care and attention ,we make no warranty concerning its content,and the magazine is provided on an>> as is <<basis.EQ international contains advertising and third –party contents.EQ International is not liable for any third- party content or error,omission or inaccuracy in any advertising material ,nor is it responsible for the availability of external web sites or their contents The data and information presented in this magazine is provided for informational purpose only.neither EQ INTERNATINAL ,Its affiliates,Information providers nor content providers shall have any liability for investment decisions based up on or the results obtained from the information provided. Nothing contained in this magazine should be construed as a recommendation to buy or sale any securities.

The facts and opinions stated in this magazine do not constitute an offer on the part of EQ International for the sale or purchase of any securities, nor any such offer intended or implied Restriction on use The material in this magazine is protected by international copyright and trademark laws. You may not modify,copy,reproduce,republish,post,transmit,or distribute any part of the magazine in any way.you may only use material for your personall,NonCommercial use, provided you keep intact all copyright and other proprietary notices.

If you want to use material for any non-personel,non commercial purpose,you need written permission from EQ International.

ACME 15 MW Solar Photovoltaic Plant at Khambat, Gujarat – A Case Study

Cover Cooper Bussmann, with headquarters in St.Louis, Missori, US, is one of the world’s largest producers of circuit protection and power quality equipment, manufacturing over 75,000 types of fuses to protect electrical, electronic and automotive systems. It is one of the leading suppliers of circuit protection solutions (Fuses & Fusegear) in world. It has set the standard for circuit protection in the global marketplace with its 85-year history of innovation. It also offers inductors and transformers designed to provide power quality in electronic applications.

Rakesh Khanna

Extreme Conditions for PV in India are the Ultimate Test for Inverters

CONTENTS Eq Business & Financial News

8-18

76

Surge Protection For PV Systems

79

Changing Global Solar PV Supply Chain Dynamics Oversupply Woes to Affect Profitability

82

Nanotechnology in the Solar Industry

84

The IEA Photovoltaic Power Systems Programme

PV MANFUACTURING 20

SOLAR ENERGY 48

Chhattisgarh Investment Limited-2MW PV Plant By Vikram Solar

26

Save Time and Costs – with 3S Modultec’s Integrated Module Production System

28

Meco CPL [Cell Plating Line]: More Power Out of Your Cell at a Lower Cost!

32

PVDF film Optimum Protection For Photovoltaic Modules

34

Demonstration Of The Benefits Of Silicone Encapsulation Of Pv Modules In A Large Scale Outdoor Array

38

Do You Really Know How Your Encapsulant Functions?

40

Importance Of Adhesive Tapes In This PV Module Manufacturing

42

UL Requirements for Polymers Applied in PV Module Assembly

Vish Palekar,

SOLAR ENERGY 56

High rate Al2O3-PECVD Backside Passivation On MAiA®-Systems

One on One with Mr. Vish Palekar

46

Reliability and Durability of PV Modules

SOLAR ENERGY

Balawant Joshi

RENEWABLE ENERGY 86

Renewable Energy Certificates – Status & Way Forward

Navodit Kumar Garg

SMART GRID 98

Smart Metering - The First Wave Of Smart Grid Adoption In India

60

Optimum Efficiency And Flexible Use High Frequency Transformer With Transformer Switchover

64

Conventional Central Inverter V/s REFUsol 333K

66

REFUconnect – A Wireless Networking Device

68

Smart Solar Power Inverter Reference Design

74

Importance Of Fuse Development For The Solar Power Market

RENEWABLE ENERGY 90

Power Electronics Packaging Revolution Module without bond wires, solder and thermal paste

94

Hydraulic System Maintenance Basics – Selecting Quality Hydraulic Lubricants

SMART GRID 96

Modelling Smart Grid Communications

EVENTS 102

SOLARCON India 2011

PRODUCTS 100-101

& EQBusiness Financial News

INTERNATIONAL

IEA launches the World Energy

Concentrated Solar Power Market

Global PV Installations to Hit 24 GW in

Outlook (WEO) 2011At a press

to Experience Ups and Downs over

2011 Predicts IMS Research. The report

conference in London, the IEA

the Coming Decade. The market for

found that despite the relatively weak start

Executive Director Maria van derHoeven

concentrated solar power (CSP) systems

to the year, installations will rise by 24%

and Chief Economis t Fa tihBirol

began a revival around 2004, at which time

in 2011 to reach 24 GW, up from 19 GW

presented the results of the IEA World

several key policy announcements inspired

in 2010. The research also revealed that

Energy Outlook 2011 (WEO).The WEO-

investors and engineers to start developing

European installations will rise by just 3%

2011 looks at how the energy system will

again. The revival gained further momentum

this year and that Italy will displace Germany

evolve in the next 25 years, taking account

in 2006, fueled by concerns about climate

as the world’s largest market. Italy the New

of the broad policy commitments that have

change and energy independence, with

Number 1, but Europe’s Share Falls

already been announced by countries around

a peak in 2007-2008 as silicon-based

the world to address climate change and

photovoltaic (PV) modules rose to record

growing energy insecurity. The WEO also

prices during a temporary global shortage

focuses on climate change issue - with an

of solar-grade silicon. A new report from

assessment of what infrastructure “lock-

Pike Research forecasts that the global

in” means for manoeuvrability to meet

CSP market will continue to experience ups

the 2 degrees Celsius goal, the potential

and downs between now and 2020, rising

implications of a rapid slowdown in the

dramatically from $2.1 billion in 2012 to

use of nuclear power for the global energy

$5.1 billion in 2013, and then experiencing a

landscape, the role of coal in an emissions-

gradual decline to $2.0 billion by 2016 before

constrained world and the consequences on

resuming gradual growth again to $4.9 billion

global energy markets of a possible delay in

by 2020. Despite this volatility in market

oil and gas sector investment in the Middle

value, the cleantech market intelligence

East and North Africa.

firm forecasts that total installed capacity of CSP will increase significantly by the end

Global Wind Power Investment to

of the decade, rising from 1.7 gigawatts

Total $820 Billion from 2011 to 2017

(GW) in 2012 to 35.0 GW by 2020. “The

. According to a recent report from Pike Research, by 2017 wind power installations will represent a $153 billion global industry, up from $77 billion in 2011. Over that period, the cleantech market intelligence firm forecasts, cumulative investment in new wind power capacity will total $820 billion.

Over that same period, total wind generation capacity, including both onshore and offshore

biggest threat to resumed growth in CSP is the dropping price of PV modules,” says senior analyst Peter Asmus. “PV modules continue to drop beyond 50% of their peak in mid-2008. In addition, the established track record of PV is more attractive to financial backers. Yet, CSP may overcome competition from PV by reducing costs as the result of bigger scale and two technology propositions that increase operating revenue

Despite a freeze and then cuts to its incentives earlier this year, Italy is forecast to become the world’s largest market in 2011 for the first time; and install 6.8 GW of new capacity.The report’s updated rankings also reveals that whilst the research firm maintains its earlier prediction that only four of the top 10 markets in 2011 will be European, it now forecasts that the UK will be one of those. “Despite installing just 45MW last year, the UK is set to install more than 500 MW in 2011 and become the 8th largest PV market. The attractive incentive levels helped kick-start the market, but the changes to the tariff during the year to prevent large-scale projects and the sudden cuts proposed for December have created a surge in demand”, explained Sharma.

The research firm predicts that the USA will become the third largest market this year, whilst China will be the fourth largest.

“Installation rates in China have rocketed since the introduction of provincial and the national FiTs; as China’s Government seeks to provide domestic demand for its huge manufacturing base whilst Europe falters.

Installations in China could reach as much

projects, will increase from 235.8 gigawatts

and profits: hybridization with fossil fuel

(GW) in 2011 to 562.9 GW in 2017 ”At

plants through a process called Integrated

the highest level, three major regional

Solar Combined Cycle (ISCC) and utility-

markets will continue to drive the global wind

sized energy storage capabilities.”

industry: Asia Pacific, dominated by China

PV Manufacturing Equipment Revenues to More Than Halve in 2012 According to IMS Research . Senior Research Analyst Tim Dawson comments: “IMS Research estimates that the PV manufacturing equipment market, after a record year in 2011 ($12.8 billion revenues), will be worth just over $5.7 billion in 2012. Massive over-capacity, coupled with a reduction in demand, has led manufacturers either to postpone or, where possible, cancel orders for new manufacturing equipment, at least in the short term.”Dawson continues: “Longer term, although a return to growth is inevitable for 2013, a strong V-shaped recovery has not been forecast. The PV manufacturing equipment market will instead steadily recover; as companies look to invest once again in new equipment to remain competitive, improve their production processes, increase cell efficiencies, and reduce the cost per watt associated with the ultimate end product.”

and, to a lesser extent, India; Europe, led

by Germany and Spain; and North America, led by the United States. Illustrating the dynamic growth of new market entrants, the top 10 wind manufacturers supplied 79% of the wind turbines installed worldwide in 2010 – a significant drop from 88% only two years before. The majority of these new entrants are based in China.

8 EQ INTERNATIONAL November/December 11

as 2.5 GW this year, with IMS Research predicting a level of around 1.9 GW to be most likely”, concluded Sharma.

www.EQMagLive.com

& EQBusiness Financial News

Green Infra Ltd commissions its first 10MW solar photovoltaic power plant in Gujarat’s Rajkot District. With the commissioning of this plant, Green Infra’s operating capacity now stands at 174 MW. The company is on track to implement an additional 150 MW by the end of this financial year, with a longer term plan to reach total generating capacity of 3,000 MW by 2015 across several renewable energy sectors.

REC modules were selected for a 5MW module solar power plant developed by Kanoria Chemicals & Industries Limited (“KCI”) which is among the first projects to benefit from the Renewable Energy Certificate Mechanism in India. REC modules are ranked in a top position for energy yield in the Photon Module Field Performance Test providing 6 percent more energy on average than competing brands.

SunEdison Secures Landmark Financing for Solar Energy Projects in India The funding, worth an estimated US $110 Million (more than INR 500 Crores), was secured by SunEdison from Overseas Priv a te I nves tmen t Corpor a tion (OPIC), L&T Infrastructure Finance Company Limited and Infrastructure Development Finance Company Limited (IDFC). “Having arranged more than US $2.5 Billion (USD) in project financing and having deployed or managed more than 500 power plants throughout the world, SunEdison has the proven experience with large-scale solar deployments that investors trust,” said PashupathyGopalan, Managing Director, South Asia and Sub-Saharan Africa, SunEdison.

Moser Baer emerges as 1st solar PV manufacturing company globally to be accredited with ‘Green Leaf Mark’ certification by Intertek AB Semco, Germany for its latest Max Series ‘Lead free’ solar PV modules. Intertek’s Green Leaf Mark certifies that this product has been independently tested and found to conform to the multiple existing environmental regulations, such as RoHS laws, REACH and Eco Design.

10 EQ INTERNATIONAL November/December 11

India

GE India names Banmali Agrawala as the new President & CEO for its Energy business.Banmali has over 24 years of professional experience and has held several senior positions in industrial companies. Most recently, Banmali was with Tata Power Company Limited, where he was the Executive Director for Strategy and Business Development, India, and also served on the board of directors for the company. From 1987 to 2008, Banmali was with Wartsila India Limited, holding several leadership positions in both India and Europe, and ultimately serving as Managing Director of the company for five years.

DEG provides risk capital for a private solar power developer in I ndia .

Germany’s bilateral development finance institution DEG - Deutsche Investitions- und EntwicklungsgesellschaftmbH (The German Investment and Development Company), member of KfWBankengruppe, has provided EUR 10 m (INR 680 m / USD 13.6 m) risk capital in the form of Compulsory Convertible Debentures (CCDs) to Azure Power India Pvt. Ltd. The financing of Azure Power represents the very first financing by DEG of a Solar Power Developer (IPP) worldwide, and is a clear sign of DEG’s commitment to the Indian solar power sector in particular, and the Indian renewable energy sector in general.

T-Solar continues its international expansion with the construction of 61 MW in India and Peru The new plant uses thin-film amorphous silicon panels produced in the company’s state-of-the-art factory in Galicia (Spain).It is located near the city of Jodhpur, in the state of Rajasthan, from which it will be feeding 8.5 GWh a year into the country’s national electricity grid.

Before year-end, T-Solar and Astonfield will connect their second photovoltaic power plant to the grid on the Indian subcontinent, this time in the Patan district in the state of Gujarat.The new plant, with an installed capacity of 12.3 MW, will generate 19.4 GWh a year.

GE Energy recently announced the appointment of Vivek Venkatachalam as the President& CEO for GE’s Converteam business operations in India, of the recently concluded $3.2 billion acquisition of Converteam globally.

Waaree has received EPC (Engineering Procurement &Commissioning) contract for 10MW Solar PV plant from MSIL (Mono Steel India Ltd), Gujarat.This project is a part of Gujarat Solar Mission.

The location for this project is in UNA, near Diu in Gujarat. Work hasbegun in full swing &plant will be connected to the gird

by December 2011. The Solar PV modules for this project are being manufactured at Waaree Energies Pvt Ltd, Surat factory Suzlon receives 23 MW order from GAIL (India) Limited. The order consists of 11 units of Suzlon’s S88 – 2.1 MW wind turbines, to be commissioned in the states of TamilNadu and Karnataka by the end of the financial year 2011–12. This is GAIL’s fourth order with Suzlon, with first two projects located in Gujarat. The first 4.5 MW project, comprising Suzlon’s S82 – 1.5MW turbines, was commissioned in March 2010, and the second 14.7 MW project is currently under execution.

48 Cities to be Developed as Solar Cities The Ministry of New and Renewable Energy proposes to develop 60 cities as solar cities.

So far, based on proposals received by the Government from various Sates, ‘in-principle’ approval has been given to 48 cities to be developed as solar cities in the country. Out of these, sanctions have been given to 37 cities which have engaged consultants for preparation of Master Plans.

The criteria set by the Ministry for the identification of cities include a city population between 50,000 to 50 lakh (with relaxation given to special category States including North-East States), initiatives and regulatory measures already taken alongwith a high level of commitment in promoting energy efficiency and renewable energy.So far, an amount of Rs.17.23 crore has been sanctioned for 37 cities, of which Rs. 2.75 crore has been released for utilization by the concerned State Nodal Agencies/ Municipal Corporations.So far, the Master plans for 7 cities namely Agra, Moradabad from Uttar Pradesh, Thane &Kalyan-Dombivli from Maharashtra, Indore from Madhya Pradesh, Kohima from Nagaland and Aizawl from Mizoram have been finalized and the development of projects is in progress.This information was given by the Minister of New and Renewable Energy Dr. Farooq Abdullah in a written reply to a question in LokSabha

www.EQMagLive.com

India Bid Outcome of JNNSM P h a s e 1 Batch II.Solar D i r e c t Emerges Lowest Bidder @ INR 7.49/KWHr NEW DELHI, Dec. 2, 2011 / EQ International / www.EQMagLive.com <http://www.

EQMagLive.com/> / Solar Energy in India is more closer to grid parity. With Grid Connected Solar Power Plant Developers in India quoting as low as Rs.7.49 per KWHr for Solar Power supplied to the grid in India.

Today at 3 PM (IST) the NVVN (NTPC Vidyut Vyapar Nigam Limited) opened the financial bids for allotting 350 MW’s of grid connected solar projects under the Batch II of Phase 1 of Jawaharlal Nehru National Solar Mission (JNNSM).French Company Solar Direct Emerges as Lowest Bidder offering Solar Power @ Rs.7.49 per KWHR while Green Infra highest bidder @ Rs.9.39 per KWHR. The Price Discovery mechanism has proved miraculous on the one side making solar energy closer than ever to grid parity and

& EQBusiness Financial News affordable while on the other side makes it a big challenge for these projects to achieve financial closure and prove viability. With these prices, Solar Power has already beaten up the cost of Diesel Power and the cost of the power traded on the Indian exchanges at times.

The JNNSM’s Phase 1 Batch II is likely to generate business around Rs.3000 Crores in next one to two years. As a mandate, Solar PV Projects using Crystalline Silicon Technology have to use Modules and Cells Made in India while Thin Film Panels can be imported. This policy of the Government is also a big boost for the Indian Solar Cells & Modules Manufacturers.

Steep falling module prices, rapid advancement in the solar technology, falling demand in German and european markets have led to massive reduction in the cost of the solar power. PV Modules Prices are at all time low of USD 90 Cents a Watt.

JNNSM envisages the implementation of the solar program me in India including utility grid solar power in three phases – first phase up to 2013 (1,100 MW), second phase up to 2017 (4,000 MW), and third phase up to

Loewst Bidders are: Developer Name

Capacity Bided

Bid Price

Soliare Direct SA

05 MW

Rs.7.49

Welspun Solar P Ltd.

20 MW

Rs. 7.97

Welspun Solar P Ltd.

15 MW

Rs. 8.05

Welspun Solar P Ltd.

15 MW

Rs. 8.14

Azur power India Ltd.

15 MW

Rs. 8.21

Azur power India Ltd.

20 MW

Rs. 8.21

Sai Sudhir Energy P Ltd.

20 MW

Rs. 8.22

VS Lignite Power Ltd.

10 MW

Rs. 8.28

Symphony Vyapara P Ltd.

10 MW

Rs. 8.48

Jackson Power P Ltd.

10 MW

Rs. 8.49

Shree Saibaba Sugar Ltd.

05 MW

Rs. 8.73

Jackson Power P Ltd.

10 MW

Rs. 8.74

LEPL Projects Ltd.

10 MW

Rs. 8.91

Sunbourne Energy Ltd.

05 MW

Rs. 8.99

Sujana Towers Ltd.

10 MW

Rs. 9.09

Fonoche Energies AS

05 MW

Rs. 9.10

Fonoche Energies AS

15 MW

Rs. 9.10

NVR Infrastructure & Services P Ltd.

10 MW

Rs. 9.16

Enfield Infrastructure Ltd.

10 MW

Rs. 9.16

Essel Infra Projects Ltd.

20 MW

Rs. 9.27

SEI Power P Ltd.

20 MW

Rs. 9.28

GAIL

05 MW

Rs. 9.32

Mahindra Solar One P Ltd.

20 MW

Rs. 9.34

Kiran Energy Solar P Ltd.

20 MW

Rs. 9.34

Mahindra Solar One P Ltd.

20 MW

Rs. 9.34

Green Infra Solar farms Ltd.

20 MW

Rs. 9.39

2022 (20,000 MW).

NTPC Vidyut Vyapar Nigam (NVVN), the trading arm of NTPC, has been designated as nodal agency for sale and purchase of grid connected solar power under Phase-1 of the Mission.

EQ INTERNATIONAL November/December 11

& EQBusiness Financial News China PV Installations Forecast to Surpass Both the US and Japanese Markets in 2011 In the Asia Pacific region, the photovoltaic (PV) market is forecast to grow 39% Q/Q and 130% Y/Y in Q4’11.

Q4’11 installations of more than 2 GW of PV capacity are expected, which will significantly raise the region’s share of the global market this year, according to the new Asia Pacific Major PV Markets Quarterly report released

by NPD Solarbuzzrecently.The region is poised to grow an additional 45% in 2012, as Asian governments introduce new installation targets. China’s National Energy Administration recently revised its official cumulative solar installation target up from 10 GW to 15 GW for 2015, representing just one of the most recent examples. China is projected to account for 45% of regional demand in Q4’11 and is on course to surpass both the US and Japanese market sizes in 2011.

Alstom has been awarded a contract by the International group, IsoluxCorsán to supply gas turbine equipment and associated services for a 180 MW simple cycle gas-fired power plant in the Khulna district of Bangladesh for the North West Power Generation Company Limited (NWPGCL). The plant will be based on Alstom’s GT13E2 gas turbine and will be capable of running on both gas and diesel, thus reducing any uncertainties in fuel supply.

Mighty River Power recently signed agreements with Okere Incorporation and RuahineKuharua Incorporation for the investigation and development of geothermal power generation on the Taheke field, 20kms northeast of Rotorua.

NhonTrach 2 combined cycle power plant goes on line in Vietnam . Siemens supplied the power block comprising main components such as gas turbines, heat-recovery steam generators, steam turbine, generator, and instrumentation and controls. The general contractor Lilama erected the power plant for the end customer Petro Vietnam NhonTrach 2 Joint Stock Company. With an installed capacity of approximately 760 megawatts (MW) and an efficiency of over 57 percent NhonTrach 2 will make an ecofriendly contribution toward meeting the country’s significant increase in power demand.

12 EQ INTERNATIONAL November/December 11

Asia-Pacific

Canadian Solar Issues Statement on Solar Trade Petition Canadian Solar, Inc., one of the world’s largest solar companies, recently issued a statement in response to SolarWorld Industries America Inc.’s trade complaint.

Canadian Solar is against the petition filed with the U.S. International Trade Commission and the U.S. Department of Commerce by SolarWorld Industries America Inc., as we believe the petition is exaggerated and without merit. We urge the U.S. authorities to put first the interest of the hundreds of thousands of American citizens and businesses who have benefited from affordable solar power either as consumers or workers in the U.S. solar industry. We believe the petition is counter-productive to the continued development of the solar industry, including the multitude of upstream and downstream businesses located in the United States, and to the development of lower priced products needed to make solar power an economically attractive alternative to traditional power sources. As a Canada-based company with manufacturing facilities in both Canada and China, we have always actively supported free trade, and have always abided by international trade law and fair practices. Canadian Solar is committed to supporting its customers and partners in the United States, to making solar energy even more affordable for American families and businesses, and to further helping the American solar industry become a sustainable, major engine of economic growth.

JinkoSolar Responds to Solar Trade Petition “We are currently in the process of reviewing the petition that was filed,” commented Mr. Kangping Chen, Chief Executive Officer of JinkoSolar. “The petition was filed by multiple solar power manufacturers in the U.S. and does not reflect the position of the U.S. Government.

We will respond in accordance with ITC & DOC guidelines. As a global company listed on the NYSE, we are confident in our position and are well-prepared to substantiate our strict adherence to fair international trade practices. Until the issue is resolved, we will continue to work with our customers and partners to ensure that our business is conducted as usual.”

Yingli Green Energy Issues Statement on SolarWorld Industries America’s Petitions . “We and our counsel are reviewing the petitions, which have just been filed. We would like to remind everyone that such petitions obviously present only the views of one side, and only a partial view of a very complicated story. As a NYSE-listed public company with global presence, we have been holding ourselves to the highest standard of fair international trade practices.

We are confident in our position and we intend to mount a vigorous defense. We are committed to the U.S. market for the long run, since we have faith in our products and technology and believe that we are well positioned to continue to compete effectively in the U.S. market.”

Suntech Response to Solar Trade Petition . “We’re currently reviewing the petition filed with the US International Trade Commission and the US Department of Commerce. Anyone can file one of these actions; having filed an action is in no way a validation from the US government as to the merits of the action. Companies listed in the petition are not subject to a single blanket judgment, and each individual company, including Suntech, will respond in accordance with ITC & DOC guidelines.

As a global company listed on the NYSE, we are confident in our position and wellprepared to substantiate our strict adherence to fair international trade practices. Until the issue is resolved, we will continue to work with our customers and partners to ensure business as usual.”

Trina Solar Response to Trade Action Filed in the United States Trina Solar, among other Chinese suppliers, was identified as an exporter of these products to the United States market.Trina Solar believes the allegations made by the U.S. petitioners will eventually prove to be unfounded and that Trina Solar’s transactions with its United States customers were made in accordance with international trade practices. The company has, and will continue to, adhere to prudent and recognized United States industry practices and standards. Trina Solar is confident that these facts will be affirmed within the proceedings.

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& EQBusiness Financial News Abengoa announces final completion of the investment by First Reserve Corporation, one of the largest international investment funds specialized in the energy industry Under the agreement, First Reserve, one of the largest private international investment funds in the energy sector, will now take a stake in Abengoa by investing €300 million in its capital structure.

Bank Sarasin’s sustainability study on the solar industry: just a few German solar companies will survive the market shakeout. A shakeout of the solar industry is inevitable as the imbalance between production capacities and demand has

EUROPE

Q-Cells Builds Superlative Photovoltaic Power Plant. The solar park being built in Brandenburg-Briest will have a capacity of 91 MW. Q-CELLS has found two renowned investors in the solar energy sector who acquired the project.

The neighbouring solar parks BrandenburgBriest West and Brandenburg-BriestOst, which are being built on land within the municipality of the city of Brandenburg, have a total capacity of around 60 MW and were purchased by the Hamburg investment company LUXCARA. Construction began immediately. The sub-project of around 31 MW being built in the Briest - Havelsee district since mid-October was bought by the MCG Group in Berlin.

ET Solar Announces Grid Connection of a 5MW PV Power Plant in Germany Code named BoerdeWest, the ground mounted PV power plant is located approximately 150 kilometers west of Berlin, Germany.

ET Solar’s subsidiary, ET Solutions AG, performed full Engineering, Procurement and Construction (EPC) tasks and ET Solar’s manufacturing subsidiary in China provided solar modules. The transaction is the fourth and the largest ground mounted PV power plant that ET Solar delivered, on turnkey basis, to Wattner AG (“Wattner”) in Germany since 2009.

Sol a r Fron tier and BELECT R IC

As specified by the federal network agency

announced that they have completed a

become too great with around 50 gigawatts

4.2 MWp solar power plant in Bessan,

(GW) of production capacity for solar

France, further strengthening their joint

modules compared with sales of 21 GW at

collaboration. The project is the first in

the end of this year. The companies best

France to use Solar Frontier’s thin-film

positioned for the next stage of growth in

CIS modules and marks Solar Frontier’s

the PV market from 2013 onwards include

entry into the French solar project market.

Suntech Power, Trina Solar and Yingli Solar

BELECTRIC installed 29,931 thin-film CIS

from China, First Solar and Sunpower from the USA and Solarworld from Germany.

modules at the site with an expected output of 4.2 MWp. Vienna-based Activ Solar announces the

MBCEL commissions 23.8 MWP solar

completion and commissioning of Phase

farm at Lauta in Germany . This solar farm

III of the Perovo Solar Power Station.

has been commissioned using crystalline silicon technology which will feed in 65,500 units daily into 20 KV local substation. The project has been constructed with long term debt funding from DKB bank, Germany which has also financed Thuringen and Meissens projects undertaken by MBCEL. ”The solar farm has been commissioned using SMA central inverters with Conecon GmbH as the construction partner.

Parabel Completes 5,3-MW Solar Park In Saxony . Almost 23,000 solar modules from Trina-Solar were installed on the previously unused, approximately 12-hectare site in the Horka industrial area. The implementation of a decentralised inverter concept with Siemens PVM inverters means that the electricity input to the grid is optimally adapted to the difficult grid situation on site.

14 EQ INTERNATIONAL November/December 11

Just weeks after the launch of Phase II, the latest segment adds an additional 20 megawatts (MW) to the project totalling 60 MW to date. The ground-mounted arrays of all 3 phases consist of over 264,000 mono and multi-crystalline photovoltaic modules and 80 central inverter stations.

Centrothermphotovoltaics AG wins two iF product design awards for photovoltaic key equipment “c.FIRE“ and “GP ISOTEST. Waf“ . The “c.FIRE“ fast firing furnace, in which the front and rear contacts are burned into wafersat high temperatures, is the latest generation of the established fast firing furnace and ischaracterized by its compact design. The “GP ISO-TEST. Waf“ enables the quality control of wafers in the solar cell production.It monitors the insulation resistance between the front and rear side of wafers and enablescontributes to the reduction of manufacturing costs in mass production.

German PV Market: Degression on Jan. 1, 2012 will be 15 percent. on 10.27.2011, the degression on Jan. 1, 2012 will be 15 percent.The amount of degression for January 2012 is based on the installed capacity from October 1, 2010 to September 30, 2011. According to data from the federal network agency, added capacity for this time period was about 5,200 MWp (3,300 from the first nine months of 2011).

The base degression is 9 percent. If the installed capacity exceeds 3,500 MWp in the months relevant for the degression calculation, an additional 3 percent degression is added for every additional gigawatt installed.

The following rates are applicable for the coming year: Roof installations up to 30 kWp, 24.43 cents / kW-hour. Roof installations up to 100 kWp, 23.23 cents / kW-hour.

Roof installations up to 1 MW, 21.98 cents / kW-hour Roof installations greater than 1 MW, 18.33 cents / kW-hour Open-space installations, 17.94 cents / kWhour JinkoSolar to Power 14MW in Solar Installations in the United Kingdom .

It was selected as the preferred module provider for a partnership between AEE Renewables plc and EPC GraessSolartechnik for three solar projects across the United Kingdom.

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solarexpo.com

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& EQBusiness Financial News

AMERICA

Obama affirms

a considerable number of questionable trade

concern about

practices, including dumping, coming out of

China’s clean-

China,” Brinser said. “We are heartened

energy trade, citing ‘a lot of questionable

to hear that the Administration is looking

competitive practices’ Obama answered:

closely at our case and the President has

“We have seen a lot of questionable

restated his commitment to enforcing U.S.

competitive practices coming out of China

trade laws.”Representing the Coalition

when it comes to the clean energy space, and I have been more aggressive than previous administrations in enforcing our trade laws.

We have filed actions against them when we see these kinds of dumping activities, and we’re going to look very carefully at this stuff and potentially bring actions if we find that the basic rules of the road have

been violated.”GordonBrinser, president of Oregon-based SolarWorld Industries America Inc., said Obama’s remarks validated concerns that China has been violating U.S. and world trade laws at the expense of U.S. domestic clean-technology employers and jobs.“The President acknowledged there are

for American Solar Manufacturing, which includes six other manufacturers of crystalline silicon solar technology, SolarWorld filed its petitions on Oct. 19. The case seeks anti-dumping and countervailing duties against Chinese solar manufacturers to offset what they allege are significant, pervasive violations.

SolarWorld and coalition of U.S. solar

of U.S. solar manufacturing and jobs.The

Yet, massive state subsidies and sponsorship

manufacturers petition to stop unfair

cases, which allege dumping margins well

have enabled Chinese manufacturers to

trade by China’s state-sponsored

in excess of 100 percent as well as massive

illegally dump their products into a wide-

industry

subsidies, are among the largest against

open U.S. market.”

SolarWorld and coalition of U.S. solar manufacturers petition to stop unfair trade

by China’s state-sponsored industry Group led by SolarWorld aims to stop loss of U.S. manufacturing and jobsWASHINGTON, D.C.,

China and the largest in renewable-energy industry history.“Artificially low-priced solar products from China are crippling the domestic industry,” said Gordon Brinser, president of SolarWorld Industries America

The petitions allege that the Chinese government its state-controlled financial, utility and other institutions intermingled with its solar manufacturing industry has

companies’ business. China actually has no

deployed an arsenal of land grants, contract awards, trade barriers, financing breaks and supply-chain subsidies to advance its pricing and export aggression. China exports nearly all of its production to benefit from other markets’ consumption incentives while increasing output and impeding imports.

Along the way, it also sidesteps U.S.-level manufacturing standards for labor, quality, and the environment.Imports of Chinese crystalline solar cells and panels rose more than 300 percent from 2008 to 2010. In July 2011 alone, exports exceeded those from all of 2010. In the first eight months of 2011, Chinese imports into the United

production cost advantage. Labor makes up a

States totaled $1.6 billion. Over the past

modest share of solar-industry costs, China’s

18 months, seven U.S. employers have shut

labor is less productive, its raw material and

down or downsized, not counting cutbacks

equipment have come from the West and

among manufacturers of a variety of new

China must pay for long-distance shipping.

solar technologies known as thin films.

Advanced Energy Industries, Inc.

Cupertino Electric, Inc. earlier this year to

first phase of a five-year PG&E plan to build

recently announced that its Solaron®

leverage the Solaron PV inverter’s industry-

250 MW of solar power. The Stroud and

PV inverters have been installed at a

leading energy-efficiency ratings and lowest

Westside installations include 70 of AE’s 500

35-megawatt (MW) solar project located

Levelized Cost of Energy (LCOE).The 35

kW Solaron® grid-tied PV inverters, which

near Coalinga, California. The project

MW project consists of two sites owned by

provide low voltage ride through (LVRT)

was awarded to Advanced Energy (AE)

PG&E: Stroud, a 20 MW site, and Westside,

and reactive power control.

by engineering and construction company

a 15 MW site. The two sites are part of the

Oct. 19, 2011 Representing a coalition of seven U.S. manufacturers of solar cells and panels, SolarWorld Industries America Inc., the largest domestic producer, today petitioned the federal government to halt

Inc., based in Hillsboro, Oregon. “As the strongest and most experienced U.S. producer, SolarWorld is leading the effort to hold China accountable to world trade law.”

what the company describes as an ever-

“China’s systematic campaign to dismantle

rising tide of heavily subsidized solar cells

the U.S. industry has cost thousands of

and panels that China’s state-supported

jobs in Arizona, California, Maryland,

solar industry is illegally dumping into the

Massachusetts, New York and Pennsylvania,”

American market.

Brinser said. “China’s wrongful tactics run

The Coalition for American Solar Manufacturing representing a significant majority of U.S. production of crystalline silicon solar cells and panels filed complaints today with the U.S. Department of Commerce and International Trade Commission seeking relief from China’s illegal trade practices.

The complaints aim to end China’s decimation

16 EQ INTERNATIONAL November/December 11

systematically across the board; central planning has subsidized most facets of these

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& EQBusiness Financial News

AMERICA

A

companies operating in the U.S. solar energy

is critical that governments and private

Statement

industry. These companies employ over

parties operate within the framework of

on Expected

100,000 American workers, including more

internationally-negotiated trade rules.

Petitions

than 25,000 in the manufacturing sector.

S

E

I

for the U.S. Government t

o

Investigate Chinese Trade Practices. Rhone Resch, president and CEO of the Solar Energy Industries Association (SEIA), released the following statement recently in response to news that certain domestic producers of solar energy products intend to file antidumping (AD) and countervailing duty (CVD) petitions with the U.S. International Trade Commission and the U.S. Department of Commerce:“There are more than 5,000 U.S. Solar Industry Coalition Applauds Unanimous Federal Trade Ruling Against Chinese Unfair Trade Practices The Coalition for American Solar Manufacturing recently applauded the U.S. International Trade Commission’s (ITC) preliminary determination that dumped and subsidized solar imports from China have harmed the U.S. domestic solar industry.In a unanimous 6-0 vote, the ITC found that Chinese imports are either materially injuring the domestic industry, or threaten the U.S. industry with such injury. As a result, both the ITC and U.S. Department of Commerce will proceed with investigations into whether antidumping and countervailing duties should be imposed to prevent further unfair losses of U.S. companies and jobs as a result of China’s anticompetitive practices.

“If it appears that trade obligations are

“As long as the U.S. is able to compete on an

not being met, solar companies - whether

even playing field, the combination of policy

foreign or domestic - have the right to

certainty, private investment and continued

request an investigation into alleged unfair

technological advances will keep the solar

trade practices. These allegations must be

industry as one of the fastest growing

thoroughly examined and, if unlawful trade

economic sectors in the country.“Global

practices are found, action to remedy those

trade in solar products has been good for

practices should be taken.“In turn, parties

the United States by expanding export

accused of unfair trade practices also have

opportunities for domestic manufacturers,

the right to defend themselves in the process

creating jobs and driving down costs to

of these investigations.“The bottom line is

consumers.“As global competition intensifies,

that these investigations provide a legitimate,

we will continue to support open markets

transparent mechanism for resolving trade

based on free and fair trade principles. It

disputes and determining what - if any unfair practices have occurred.”

argued for months: Without any production cost advantage, dumping by Chinese solar manufacturers and massive subsidies by the Chinese government are enabling Chinese producers to drive out U.S. competition,” said Gordon Brinser, president of Oregonbased SolarWorld Industries America Inc., the largest U.S. manufacturer and leader of CASM. “Today’s ruling further erodes the credibility of denials by Chinese manufacturers and their importer allies in this case.”Comprised of seven companies that manufacture crystalline silicon solar cells and panels in the United States, CASM supports SolarWorld’s allegation that Chinese solar cells and panels, heavily subsidized by the Chinese government, are flooding the American marketplace with artificially low prices intended to put the U.S. solar industry out of business.

last year alone, the Chinese government provided its manufacturers with over $30 billion in subsidies, including $7 billion alone to one company, Suntech. As a result of a sprawling portfolio of Chinese subsidies, U.S. solar manufacturers have been forced to close or downsize their operations, leading to the elimination of nearly 2,000 hightech American jobs in multiple states and the disruption of communities and local businesses. Among the direct solar job losses were 800 jobs in Massachusetts, 117 in New York, 328 in Maryland, 266 in California and hundreds more in other states.Earlier today, 59 members of Congress wrote President Barack Obama expressing their support for the case. Rep. Cliff Stearns, chairman of the House Energy and Commerce Committee’s Subcommittee on Oversight and Investigations, also has called for a thorough investigation of Chinese trade practices within the solar market.

“The ITC’s unanimous ruling underscores what American solar manufacturers have

The Department of Energy estimates that

Phoenix Solar USA builds 1.4 megawatt

GE Working to Cut Solar Installation

Copper replaces silver: multicrystalline

solar plant in Tennessee . US subsidiary

Costs in Half, Make Rooftop Solar More

solar cell with low cost metal contacts

Affordable “Today, the average cost of

achieves 18 percent efficiency . Schott

of the company, Phoenix Solar Inc., built

installing a solar system on a typical home

Solar AG and its project partners have

a strategic alliance with Silicon Ranch

is $6.50 per watt, or $32,500. We want

already reached an important milestone in

Corporation to develop and construct solar

to cut the cost by more than half. At less

the research project Las VeGaS after only six

photovoltaic power plants in Tennessee and

than half the price, solar systems will be

months: a solar cell metalized with copper

practical for millions of homeowners in

achieved an efficiency of 18.0 percent. A

the United States,” said Charlie Korman,

multicrystalline wafer from SCHOTT Solar

Manager, Solar Energy Programs at GE

AG that features standard screen-printed

Global Research.

backside metallization serves as the basis.

the Southeast. Phoenix Solar, with support from Chapel Electric, has begun construction on the Pulaski solar plant.

18 EQ INTERNATIONAL November/December 11

www.EQMagLive.com

P V M A N UFA CT URI N G

High rate Al2O3-PECVD Backside Passivation On MAiA®-Systems ROTH & RAU

When c-Si wfr thickness goes down, more IR-Light should be reflected on rear side for a 2nd pass trough to recover ŋ. This so called “PERC”-cell concept requires double side passivation coating plus local rear contacts.

A

luminium Oxide was demonstrated to be a perfect surface passivation

layer for p-type Si cause of the high amount of negative fixed charges. This fixed charges are formed in the film after thermal annealing and firing and will provide a strong field effect.

For this reason Al2O3 films will become very important as rear side passivation for future c-Si PERCcell technologies. A new high rate PECVD process for amorphous Al2O3 films has been developed on Roth & Rau’s MAiA® inline deposition machine. It was tested successfully as rear side passivation on PERC-type solar cells made by ISE Freiburg as well as by Roth&Rau pilot line.

20

EQ INTERNATIONAL November/December 11

The complete PERC cell passivation consists of a front antireflection coating plus a rear side Al2O3/SiNx stack as an “all in one” low cost solution for three dielectric coatings in just one pass through on Roth & Rau’s MAiA® inline tool with more than 3,600 wafer per hour. The total cost of ownership for TMAl (Trimthylaluminum)

come to approximate 1ct/cell. TMAl is available as a low cost “Solar grade” quality and will be offered from different chemical suppliers.

Roth & Rau’s MAiA® inline deposition system constitutes a production proven PECVD machine with standard linear MW-plasma sources, slightly modified gas showers as well as an additional liquid chemical vaporizer box with absolute TMAI-flow control and automated refill from a remote tank for continous production.

It is an advanced form of the SiNA® PECVD tools. It offers a variety of process technologies that target improved cell efficiency of crystalline silicon solar cells. Like the SiNA®,

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the 2nd generation MAiA® systems have a modular design. The process tool consists of a series of process and buffer modules. This enables running several processes in one machine. The MAiA® can deposit multilayer coatings on the front and backside of the wafer in one single tool.

Backside passivation with aluminium oxide (Al2O3) is the most important process featured by the MAiA® systems. The most common application uses double-sided coating of solar cells with a (standard) silicon nitride layer on the front and a stack of aluminum oxide / silicon nitride on the backside. The first tool of the 2nd generation MAiA® for Al2O3 backside passivation was delivered to a major German cell manufacturer in April 2011. During pilot production at the customer’s site, cells with Al2O3 layers reached 19.0% efficiency on mono crystalline and 18.0% on multi crystalline wafers. The MAiA® Al2O3 layers have been successfully tested on both p-doped and n-doped wafers as well as UMG material. nnn

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solarindia www.solarindia.net EQ INTERNATIONAL November/December 11

21

P V M A N UFA CT URI N G

Advanced Wire Sawing Technology For Solar Photovoltaic Cells Applied Materials

For solar cells to be competitive in an energy supply market ultimately driven by the cost per watt, the Total Cost of Ownership (TCOO) of each production step in the PV value chain (Figure 1) takes on critical importance. The manufacture of crystalline silicon wafers is no exception: the TCOO for a processed wafer is a key driver of overall cost.

T

he wafering process begins with solid ingots made of single-crystal or multi-crystalline silicon material.

Wire saws shape the ingots into squared blocks (Figure 2), and then slice them into thin wafers. These wafers are used as the base for the active PV cell. Wire sawing is nowadays largely - if not exclusively Achieved by means of Multi-Wire Saw technology (MWS). This document offers an overview of the wire sawing process and its manufacturing challenges, showing how next generation wire sawing technology can lower the cost of both squaring and wafering.

Wire Saw History The first practical machine for PV wafering was introduced in the mid 1980s, based on the pioneering work of Dr. Charles Hauser, founder of HCT Shaping Systems, Switzerland. (Now the Precision Wafering Systems division of Applied Materials.)

These machines used moving wire carrying abrasive slurry to create the cutting action.

Even now, the most prevalent type of saw for shaping and slicing wafers from ingots retains 22

EQ INTERNATIONAL November/December 11

the same basic architecture as Dr. Hauser’s original machine, but with greatly increased load capacity and cutting speed.

The Sawing Process The heart of a modern wire saw is a single steel wire, 110µm-140µm in diameter, wound on wire-guiding rollers. This wire guide is carefully grooved at a constant pitch, forming a horizontal net, or web, of parallel

wires (Figure 3). Powerful drives move the entire web at the same relatively high speed (10-20 m/s). The slurry, a suspension of abrasive particles in coolant fluid, is fed onto the moving wires by manifolds (or “nozzles”).

The wires transport the slurry into the cutting zone. The silicon material to becut is fixed to a table that moves vertically against the cutting head. This motion pushes the material through the wire web, producing a large number of bricks or wafers simultaneously.

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wafers produced in a given time, and depends on the following factors:

Figure 3: Schematic of multi-wire saw. Silicon Blocks are passed through the web of cutting wires

In a slurry-based MWS, the cutting action is essentially that of a fast three-body lapping process characterized by a rolling & indenting cutting mechanism [1].

The sawing principle is straight forward; the challenge is in the execution. The wire saw must precisely balance the wire diameter, cutting speed, and total cutting surface area in order to achieve precise geometry control and high yield without wire breakage.

Reducing Costs The TCOO of a MWS in wafering applications depends on 4 key elements, in decreasing order of importance: polysilicon market price, wafer yield, cost of slicing consumables, and productivity.

Yield improvement offers the greatest leverage in reducing wafering costs, while little or no action is possible on raw material cost. The wafer yield, defined as the usable surface of wafers produced per unit mass of raw material, is affected by two detractors: the loss of raw material due to the slicing process (“saw dust” or kerf loss) and the cost of any out-of-specs wafers produced by the cut. Silicon usage can be improved by reducing the kerf loss, or by reducing the thickness of the wafers while maintaining the cutting quality. The wafer thickness is defined by the pitch of the wire guide, while the kerf loss depends on the wire diameter and the abrasive grit size. Over the past decade, silicon PV wafer thickness has been reduced from 330µm to today’s typical 180 µm thickness, and this trend is expected to continue.

The wire diameter, meanwhile, has been reduced from 180-160µm to today’s typical range of 130-100µm.

Crystalline silicon PV cell manufacturers demand extremely high wafer quality, with no or minimal surface damage (micro-cracks, saw marks), minimum topography defects (warp, bow and thickness variation) and minimal need for additional downstream processing. As discussed below, wire diameter and grit size are important factors in wafer surface quality.

Finally, consumables cost and productivity enhancement offer additional avenues for cost reduction.

Slurry consumption, wire wear, slurry recycling, and wire replacement time can all play a role. Recycling in particular has become a very powerful and efficient tool for cost reduction in a wafering plant. From their market introduction in the early 2000s until today, recycling technologies based on mechanical and chemical separation principles have consistently and markedly reduced slurry cost while providing environmental benefits.

Today, most end-users are slicing wafers with a mix of slurry composed of 70% to 80% recycled components (i.e., liquid coolant and abrasive SiC grit) complemented by virgin materials.

1) Table speed (or feed rate) is the speed at which the cutting table holding the ingot to be sliced passes through the moving wire web. As the ingot enters the web at the start of the cut, pressure builds up between the wires and the silicon. The abrasive slurry sandwiched between them begins to chip at the silicon through an abrasion mechanism refered to as “rolling and indenting”.

The delay between the pressure build up and the beginning of material removal causes a bowing of the wire web. Once the material removal rate matches the table’s rate of descent, the cut has reached kinematic equilibrium.

For a given table speed and load, this equilibrium is largely determined by the wire speed, the slurry cutting ability, and the wire tension.

2) Load - the total cutting area for each run, i.e. wafer area times number of blocks per load then times number of wafers per block. The number of wafers per block is determined by the length of the silicon brick/ingot divided by the groove pitch of the wire guide.

3) Wire diameter - a thinner wire diameter means reduced kerf loss. However, thinner wire is more prone to breakage, and the wire wears during the process of cutting. Its change in diameter drives both the risk of wire breakage and the wafer quality. Optimization of wire consumption involves finding the besttrade off between wire wear and breakage risk: a system that tolerates more wire wear will consume less wire, but risks more frequent breakage. For a given application (load, wafer thickness, etc.), the higher the ratio of the table speed (or feed rate) to the wire speed (vT/vw), the faster the wire wears.

Main Process Variables The goal of the wafering process is to increase throughput while maintaining best in class yield.

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Throughput is defined as the number of EQ INTERNATIONAL November/December 11

23

4) Serviceability or change-over time - the faster the saw can be serviced between cutting runs, including replacing the wire and slurry, the higher the overall productivity.

Advanced Wire Technology

To meet market demand for lower costs, wire saw platform architectures must not only allow for load optimization, but must

Ideally, manufacturers would like to maximize the load size. Cutting a larger volume of silicon at once produces more wafers in a given amount of time, maximizing productivity. The Applied HCT B5 (Figure 4) is the only system in the market that is equipped to handle a larger load size (2 meters) giving manufacturers the flexibility to optimize load in order to maximize productivity without sacrificing yield.

Figure 5, 6, and 7 provide metrology charts for 0.85 meter and 1.73 meter loads, demonstrating that load increase can boost productivity without compromising wafer yield. With a 1.73 m load and 210 µm/min table speed, 98% of wafers met specifications set at 30 µm TTV, 20 µm TV, and 20 µm saw mark.

BKM comparison

Standard Structured Wire 250µm

Thick Structured Wire 300µm

Kerf loss per ingot (GEN 5 x 250 mm)

2.05 kg per block

2.34 kg per block

Productivity

100%

170%

CoO

100%

75%

Bricks specifications

±0.25mm @ 95%

±0.25mm @ 95%

Figure 9: Structured Wire on Multi Squaring

also be able to accomodate advances in wire technology. The B5, a proven wafering system in high volume manufacturing, is capable of handling thin wire and is easily upgradeable to advanced technologies like structured wire and diamond wires.

Structured wire (Figure 8) is an evolutionary wire technology that can significantly increase productivity due to more efficient transport of slurry and faster cut rate. Applied HCT has pioneered structured wire technology for both wafering and squaring. Proprietary thick structured wire is already proven to increase productivity by 70% and reduce COO by 25% on the Applied HCT Squarer (Figure 9). Applied HCT is currently working on process development for the use of structured wire in wafering applications.

The major challenge is the web management of structured wire due to the reduced breakage load.

However, we expect to ultimately achieve a faster cut rate with no impact on wafer quality.

Next generation diamond wire (Figure 10) is designed to further reduce costs by eliminating slurry while further increasing the cut speed. Diamond wire represents a radical change to the wire sawing process.

The diamond wire is essentially a wire surface embedded with diamond particles.

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The diamond grit size and concentration depend on the application, for instance on whether multicrystalline or monocrystalline silicon material is being sawed. The diamond particles act as the abrasive, eliminating the need for SiC abrasive and resulting in a much cleaner and more environmentally friendly process. As with structured wire, the diamond wire technology is suitable for both wafer slicing and brick squaring applications.

The Applied HCT squarer and B5 platforms can be extended to diamond wire with a hardware upgrade, making the switch to diamond wire technology more cost effective as customers need not invest in a new platform.

Recently, the Applied HCT diamond wire squarer program has achieved a cutting speed of 4,000µm/min with 100% of bricks in specification in the lab. Meanwhile, Applied HCT is aggressively pursuing a diamond wire wafering solution. Initial results show that monocrystalline silicon cutting with PEG coolant can be easily achieved. The next challenge is to optimize the multicrystalline material load length with water-based coolant in order to completely eliminate PEG recycling cost while still enjoying a high cut rate.

CONCLUSION As raw material accounts for a large part of the cost of c-Si based solar cells today, wire sawing technology is critical in reducing the cost per watt and allowing PV to reach price parity with grid electricity. Three major advances in wire sawing technology have helped to decrease the amount of silicon material required to produce solar electricity (grams per watt).

First, by enabling the cutting of thinner wafers. The historical trend has seen about 50 microns reduction in the wafer thickness every 5 years from 330µm in 1995 to 180µm today. The trend is unlikely to continue at that pace: the increasing fragility of the wafers as the thickness decreases requires advanced automation technology to handle the thin wafers with minimum stress. This is particularly true in the post-slicing step of separating the wafers from the as-sliced stack (also called “singulation”) and in the cell process manufacturing line. Parallel improvements in the slicing process are also needed to reduce thickness variation of the wafer in the same proportion to the thickness.

Second, the use of smaller abrasive grit size. The grit size plays a critical role not only

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in raw material savings by reducing the kerf loss, but also in reducing the “wedge” effect produced by the uni-directional movement of the wire: the wafer is thicker where the wire enters the brick compared to the thickness where it exits. (This variation is ambiguously called “Total Thickness Variation” and is noted TTV.) Smaller abrasive grit also induces shallower surface damage during slicing compared to coarser grits, thereby requiring less saw damage removal in the downstream cell line. Reducing damage also improves the mechanical strength of the wafer, reducing handling losses.

Finally, the reduction of the wire diameter over the years has helped save raw silicon material. The wire diameter dropped from 180µm in the mid-1990s to typically 120µm today (with some production excursions at 110µm or even 100µm, and down to 80µm at R&D level).

While the wire saw industry continues to reduce the cost of wafering processes based on straight wiretechnology, emerging wire sawing technologies such as structured wire and diamond wire will further drive down the cost, giving higher productivity and less consumable cost with the same or better wafer quality. nnn

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CONTACTS www.EQMagLive.com or email EQ November/December 11 toINTERNATIONAL Piyush.Mishra@EQmag.net

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Save Time and Costs – with 3S Modultec’s Integrated Module Production System Meyer Burger

Highest quality at lowest production cost Production of a solar module involves many process steps: Using a fully automated production line, there are typically about 20 of them. If a production line for solar modules is built by simply arranging the machinery in the right sequence, neither the interfaces nor the process times will be properly coordinated. As a result, the overall production process will not run smoothly and the individual machines will only be partially used to capacity. The negative impact this has on the performance and ultimately the output is fatal.

Accordingly, 3S Modultec has developed a vision in which the different machines are not seen as individual, closed processes, but rather as substeps in an integrated process system. First of all, we worked to coordinate the substeps with each other and simplify the subprocesses. In a second stage, we standardised the human–machine interface (HMI) across all of the processes, resulting in an enormous simplification of the handling for the operator.

We have completed this adjustment process for manual, semi-automated and fully automated systems, all the while concentrating on building systems that we can put together in a flexible manner to meet the specific needs of our customers.

This technology is enabling our customers to obtain optimum throughput with the highest possible system utilisation.

As a result, investment costs have declined significantly while the yield has increased.

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Fastest line expansion at minimum cost Our experience suggests that the production system’s successive expansion must be taken into account early in the customer’s growth strategy. For example, a customer who begins module production with a semi-automated 25 MW production system will typically want, after only a couple years of production, to increase either the level of automation and/or the system throughput.

factory size to accommodate a 65 MW system. Accordingly, the footprint of the 25 MW system is configured in such a way that the components needed to expand the system can be integrated into the existing line with minimum expense. The same

Based on this insight, w e c a n provide the customer with appropriate advice from the ver y st ar t and recommend, for example, designing the

principle is applied if a manual workstation is to be replaced with a fully automated process step Such forward-looking project management reduces production downtime that can occur during expansion work to a

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minimum, thereby helping again to maximise the yield.

Up to six months’ head start on module certification (time to market) More than just a working production system is required before the customer can begin production. On the one hand, ICEcertified modules are necessary so the finished product can be sold at an appropriate price. On the other hand, the employees need to have the right expertise to be able to manufacture the certified modules at the requisite high quality level, including understanding of the individual components in the production system and how to use them.

As a general rule, the certification process cannot start until after the SAT. Once the module design has been worked out and the tests have been performed, the test module is sent to TÜV Rheinland. Depending on the circumstances, the process may already have taken three to four months up to this point. It can take up to a further four months for TÜV to complete the factory inspection and perform the module tests. Once the certificate has been issued, the customer can begin production. Otherwise, it is necessary to manufacture new test modules and have TÜV Rheinland

repeat the test procedure.

We offer a certification service that simplifies and shortens the timeconsuming and complex process of obtaining module certification. The certification process is launched shortly after the order for the production system has been received. If required, we provide support regarding the module design and the choice of materials.

Then, we manufacture the modules needed for testing at 3S Photovoltaics and send them directly to TÜV to obtain the precertificate.

In this way, the customer typically gets

a head start of four to six months on the road to producing and selling IEC-certified modules after the successful SAT.

Integration of production employees and knowledge transfer Employee training plays a crucial role in ensuring the quality of the modules and the efficiency of production. Our “knowhow transfer” training programme

familiarises employees with the relevant materials and technologies so they can do their work expertly and focus on the critical aspects of the production process. This is a benefit that ensues from our many years of experience in module production.

Following three weeks of intensive training, the employees will perform their jobs at a high level. All participants receive a 3S certificate confirming their successful completion of the training programme.

Thanks to the certification service and know-how transfer programme, our customers can attain full production readiness in a very short time. Otherwise they would face a delay of up to six months before the start of production. Clearly, our certification

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service and employee training are good investments.

Best total cost of ownership (TCO) in the market 3S Modultec offers its customers integrated production systems with machines that are optimally coordinated and have well-defined interfaces, and also provides sound expertise based on its many years of experience in module production, ensuring the fastest possible start of production through short ramp-up times and its certification service.

We can also provide consultation for the entire factory planning process, including logistics, warehousing and much more. We will help customers to calculate and optimise the total cost of ownership, and will show them how the choice of the right cell, the number of layers and other parameters will influence the costs. We have developed an iPhone app (called “3S Modultec”) to allow customers to perform their own sample computations to get an idea of the potential costs and their consequences. This application can be downloaded free of charge on our website at www.3-s.ch or from the app store.

All of these factors help our customers to ensure that the capital invested is put to the most profitable use. nnn

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Meco CPL [Cell Plating Line]:

More Power Out of Your Cell at a Lower Cost!

Ravinder Bhardwaj; Business Head – Solar Division, NMTronics India Pvt Ltd.

Technology has unveiled & running successfully to reduce the Silver consumption by 40% & enhance the Cell Efficiency minimum by 0.3% – 0.5% (multi and mono)

T

he Meco CPL is based on the robust and proven concept of the Meco EPL [Electro Plating Line] which has, with more than 400 machines installed worldwide, built up a reputation in the semiconductor world for lead frame plating applications. CPL concept is based on EPL.

production method within the PV industry although there are areas for further improvement. Typically screen printed contact fingers are printed 120 micron wide to obtain sufficient electrical conductance. To further increase the cell efficiency the contact finger width can be reduced as the active area of the cell increases (less shading). However,

Conventional Process

A vast majority of Si cells is produced by screen printing silver paste onto the front side of the wafer. To form electrical contact with the cell emitter a firing step is done afterwards. This is a well established 28

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efficiency improvement: the process starts on a narrow and thin seed layer of Ag paste where the electrical conductance of the contact finger is further enhanced by electroplating either Ag or Ni-Cu-Sn onto it. This gives a narrow contact finger while the resistance value is also improved at the same time. With the CPL, an overall absolute

Proposed MECO Process

cell efficiency improvement is limited as the poor aspect ratio of screen printed contact fingers leads to an increase of the contact finger resistance value at the same time.

Meco offers a real solution for cell

cell efficiency improvement of up to 0.5% can be obtained and also expensive Ag paste can be saved as only a narrow and thin seed layer is required. Therefore with the CPL an RoI [Return on Investment] of < 1 year

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•

Metal options Ag or Ni-Cu-Sn

•

Plating thickness (typical) Ag : 5 micron , Ni : 1 micron , Cu : 8 micron , Sn : 3 micron

•

Production capacity 50 - 100 MW / year

•

Plating on front side / backside or both sides at the same time. This makes the Meco CPL the ideal choice for metallization of bi-facial cells.

•

Decrease Shading effect by using fine line fingers + Plating.

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Reduction of line resistance (mΩ/cm).

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Cell efficiency increase of 0.3 to 0.5% (abs) achievable.

•

Absolute efficiency >18.90% achieved on mono & 16.8% ON Multi-c.

•

FF >82.3% after plating.

•

Vertical Wafer Handling.

•

Low Drag over of chemistry.

•

High Deposition Speed (15-20 ASD).

“NMTronics India Pvt Ltd. is the authorized distributor for Meco (Meco Equipment Engineers B.V.) plating equipment in Indian sub continent.”

SEM - Electroplating Ni, Cu & Tn onto Silver Paste

can be achieved! The total CPL throughput is 1,500 to 3,000 cells / hour.

semiconductor world for leadframe plating applications.

The Meco CPL is based on the robust and proven concept of the Meco EPL which has, with more than 400 machines installed worldwide, built up a reputation in the

Specifications: •

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Cell size up to 6 inch x 6 inch (crystalline cells)

Cell Plating Line

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A Close Look Into The Role An Encapsulant Can Play In Increasing The Power Of A Thin Film Solar Module Ivan Sinicco - Head of Module Technology, Oerlikon Solar

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hen looking at the various options available for developing solar technology, which type of solar technology makes the most sense for India to invest in? Two factors in particular combine to make a strong case for thin film technology in particular. First, a domestic content clause has driven project developers away from crystalline silicon (c-Si) panels toward thin film. Secondly, as one 30Â

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of the countries in sunbelt regions around the world, India is particularly suited for thin film photovoltaic technology, since the

technologyâ&#x20AC;&#x2122;s great performance in high temperature conditions gives it an advantage compared to crystalline PV technology.

Focusing in on thin film technology, continuous innovation is critical in driving down the production costs of thin film silicon PV modules, which is a key achievement in paving the way for thin film technology and helping India

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reach grid parity, which is expected to be reached between 2017 and 2022, according to experts. At a more granular level, depending on the technology used to produce thin film, the encapsulant in particular can play a critical role in increasing the power of a thin film solar module.

To provide further detail, thin film technologies are generally categorized by the geometry of the module construction, particularly with regard to where the sun is hitting the cell. Using the encapsulant as a reference, if the encapsulant is in between the front cover of the module (generally glass) and the cell, this geometry is called substrate configuration. If the encapsulant is between the back cover of the module (generally glass or back sheet) and the back contact of the cell, this geometry is called superstrate configuration.

In the first case, the substrate configuration, the amount the encapsulant contributes to increasing the power of the cell will be related to the lower reflection and absorption losses of the encapsulant itself. The reflection losses (the major effect) are generated mostly by the imperfect index matching of the contacting interfaces (generally glass and the cell). These losses could be improved by producing encapsulants with graded refractive indexes; however, this is a very difficult task, particularly in situations where we approach high values of the refractive index with polymers while maintaining the required high transmission.

The absorption losses (the minor effect) are related to the fact that there is some natural absorption by the material composing the encapsulant itself. The more transparent (or the thinner) the material is for the desired wavelengths, the lower the absorption caused by the encapsulant itself and the higher the amount of photons that will reach the cell to be converted into electricity. The absorption and reflection losses caused by an encapsulant in the substrate configuration are very unlikely to improve too much. The only chance for improvement is to perform a better match at the cell level.

For the superstrate configuration – the most common for thin film technologies – the encapsulant is in intimate contact with the back side of the cell. In this case, the encapsulant “touches” the back contact of the cell directly and its ability to increase the power delivered by the cell itself will depend on how this back contact is made.

Almost all thin film technologies are using a “metallization” process for the back contact, using a vacuum process to generally deposit aluminum and silver compounds to create a conductive reflective layer. This metallic layer reflects the light in a nearly reflective way that was not captured by the cell itself in the first “pass trough” enabling a “second” chance for the photons to be captured. In this case, the encapsulant has no major role in improving the power of the thin film module. Conversely, it could reduce the power of the cell if the chemistry of the encapsulant is interacting in some way with the cell itself.

One technology available in the market that is not using the metallization process as back contact formation is the one proposed

by Oerlikon Solar. This technology uses TCO (Transparent Conductive Oxide) as back contact. In this case, not only can the transparency be adjusted, but the morphology of the layer is naturally structured in very small pyramids which, if coupled with a good reflector, will strongly enhance the light scattering toward the cell, resulting in a more efficient light collection by the cell if compared to the simply reflective strategy.

This kind of TCO is obtained by using a so called LPCVD (Low Pressure Chemical Vapor Deposition) process to deposit a layer of ZnO (Zinc Oxide).

In this case, the encapsulation foil design plays a crucial role. The foil must be designed in such a way that the following characteristics are present: •

Protecting the module against natural environment stresses

•

Serve as an excellent reflector

•

Be chemically “inert” toward the cell design

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Oerlikon Solar has developed, in cooperation with the major encapsulation foil manufacturers, a product that is currently available in the market. The resulting product is a white matte polymeric foil. This white matte foil, in combination with the textured surface generated by the LPCVD ZnO technology, provides the expected superior light scattering enhancement, increasing the relative power of the module.

Another alternative to this cell configuration is using a transparent encapsulation foil and a very reflective back cover. The disadvantage of this approach is higher losses by absorption of the foil itself (the photon must pass twice through the foil thickness before reaching the back contact interface). The superior light management this approach enables is not only a significant power increase but also, using the correct pigment charging of the foil, enables the ability to reduce the foil thickness. This combination produces two highly desirable effects: module power increase and module cost reduction.

Understanding the innovations at a solar cell level, such as the role an encapsulant plays in substrate and superstrate cell configurations, enables developers to increase the power of a thin film module and thus expand the potential for thin film PV technology overall. Using such technological advances to help produce increasingly efficient modules is a key step toward lowering solar power costs and driving adoption as India progresses toward its goal of becoming one of solar’s emerging global markets. nnn

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PVDF film Optimum Protection For Photovoltaic Modules From early-day applications such as architectural coating, pumps, valves & fittings to the latest applications like water membranes and lithium ion batteries, Polyvinylidene Fluoride (PVDF) has delivered only the good. In the current era of solar energy, PVDF films can be used for backsheet and front sheet application. This article focusses on key advantages offered by PVDF films in photovoltaic modules.

Mandar Amrute and Ron Partridge Poly vinylid en e f lu o rid e, m o re commonly known as PVDF, belongs to the fluoropolymer group. As per definition, a fluoropolymer is a polymer containing fluorine in its molecular structure. PVDF Copolymer is made with Hexafluoropropylene (HFP) as co-monomer.

PVDF a s com p ared to o ther fluoropolymers has key advantages such as ease of processing, availability of a wide range of products for extrusion, injection moulding and blow moulding, with the widest processing window in the entire fluoropolymer family. PVDF in the form of films processed via melt processing is generally used in photovoltaic modules as backsheet.

Backsheet construction and purpose For crystalline silicon modules, the primary purpose of the backsheet is to provide physical protection to wiring and other components, electrical insulation, in case 32

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the encapsulant resin becomes significantly thin during the lamination process. Since a PV module is an electrical device, it is important to select backsheet materials that will enable safe and reliable operation of the module for the longest possible time.

PV modules prove to be truly ‘green’ when they can continue producing electricity well beyond the 25-year warranties typically offered by module makers.

Backsheet constructions have a polyester

[Polyethylene Terephthalate (PET)] film layer sandwiched between two fluoropolymer film sheets. The purpose of the PET film is to provide electrical insulation and cut-through resistance.

While PET is a good insulator, it is susceptible to environmental degradation, including the effects of UV and moisture.

Fluoropolymer films, eg, Kynar® PVDF are laminated on both sides of the PET film to protect it from chemical & Ultraviolet (UV) attack and ensure longevity of backsheet construction.

Fluoropolymer films, including PVDF, are known to be resistant to UV degradation, fire, moisture and environmental pollutants like acid rain.

These protective fluoropolymer films also serve to block UV rays from reaching the PET layer, and further enhance the longevity of the construction. The use of PVDF film on both sides (eg, KPK®) ensures safe and long-lasting performance.

Outstanding UV resistance Since the primary purpose of the outer fluoropolymer film is to protect the PET layer from the environment, the fluoropolymer film

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itself must be completely resistant to UV degradation and environmental exposure.

Due to the chemical structure of PVDF, it is completely resistant to UV degradation, chemical pollution, moisture, etc. One of the easiest ways to evaluate a material’s resistance to weathering is to determine whether the surface is changing, and whether mechanical properties are affected upon exposure.

to the other fluoropolymer material. While the other fluoropolymer film is a good, weather-resistant polymer and comparatively better than most other materials, it is not as resistant to weathering as Kynar® film.

This high level of weathering performance is due to high fluorine content of PVDF, which confers it the property of extreme resistance to weathering, fire resistance, chemical & moisture resistance and excellent dielectric

to thermal degradation, Underwriters Laboratories Inc (UL) – an organisation that conducts certification testing of electrical appliances – requires that a relative thermal index test be conducted on backsheet materials of construction. In comparison with other fluoropolymer resins and most other materials, PVDF has greater oxidative and thermal stability.

Module makers PVDF film is well recognised by major module makers around the world as an extremely durable and cost-effective material for photovoltaic backsheets.

PVDF backsheet protection film comes in a variety of width. This product has been designed to work with rollto-roll lamination processes used by backsheet producers worldwide. Photovoltaic modules produced using PVDF-based backsheets meet all requirements established

by UL and the International Electrotechnical Commission (IEC).

In order to prove this, the Scanning Electron Microscopy (SEM) micrographs of the surface of Kynar® Film 302 PGM TR (architectural coating resin with weather resistance) and another widely used fluoropolymer film can be compared. The surface of the Kynar® film remains completely unaffected after 10,000 hours of accelerated weathering (QUV B 313 nm, irradiance = 0.89). The other fluoropolymer film shows pitting and chalking on the surface after exposure.

Kynar® film shows only slight reduction in elongation properties over time as compared

Ensuring varied applications properties. As fluoropolymer materials are among the best weather-resistant materials available, most other non-fluoropolymer materials do not provide the required longterm performance.

Oxidative and thermal stability Depending on varied environment conditions, PV modules may become hot for extended periods, which can shorten the lifetime of many polymeric insulating materials. To assess long-term resistance of materials

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As PVDF offers significant advantages in manufacturing, such as chemical resistance, lubricity, mechanical strength and oxidative & thermal stability as compared to other thermoplastic materials, it finds numerous applications across various industry verticals.

It has proven applications in architectural panels, chemical processing industry equipment, pumps & valves and polymer processing aid for polyolefins. nnn

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Demonstration Of The Benefits Of Silicone Encapsulation Of Pv Modules In A Large Scale Outdoor Array Barry Ketola, Chris Shirk, Philip Griffith, Gabriela Bunea (1) Dow Corning Corporation, Midland, Michigan, USA (2) SunPower Corporation, San Jose, California, USA

Based on the historical performance of silicones in both the construction and electronic industries, silicones are known for their superior performance in outdoor applications. This performance makes silicone materials well suited for solar photovoltaic (PV) modules in their application as a semiconductor device made for outdoor use. Silicone applications within the module include encapsulants, potting materials, and junction box and frame sealants. Dow Corning has developed a number of silicone-based products for use in PV module construction including the Dow Corning® PV- 6100 Cell Encapsulant Series product line launched in 2009. To demonstrate the product line performance in real-world conditions, 15 kilowatts of mono-crystalline matrices were purchased from SunPower Corporation, San Jose, California, USA under the United States Department of Energy Solar America Initiative Program. The matrices were encapsulated on the Pilot Line in Dow Corning’s Solar Solutions Application Center in Freeland, MI USA. The silicone-encapsulated modules were installed as part of a 30 kW PV array at the Dow Corning corporate headquarters in Auburn, Michigan in 2009. The balance of the array was constructed using 15 kW of EVA modules purchased from SunPower Corporation, using identical cell and glass technology to compare efficiency and durability.

W

hile silicones for PV module encapsulation have been used since the 1970’s, the market has historically been dominated by organic materials such as ethylene vinyl acetate (EVA). However, these organic materials typically utilize UV-blocking agents that have been shown to reduce overall energy conversion efficiency between PV cells and modules. Silicone encapsulants have the potential to overcome this disadvantage with the proper product design in combination with processing, 34

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and equipment engineering.

As reported in previous EU PVSEC conferences, Dow Corning has been working to develop a new generation of silicone encapsulants to leverage the advantages of silicones while also creating a product and process combination that meets or exceeds industry requirements.

The Dow Corning® PV-6100 liquid encapsulant series has been the result of this effort, and this material was officially launched at the 2009 24th EU PVSEC in Hamburg, Germany. A key milestone in the

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commercialization of this product line has been the demonstration of this product/process combination at full production scale, and the subsequent creation of a significantly large array of PV modules that demonstrate the performance of PV-6100 series products in realworld conditions. This demonstration also included an array of organic (EVA) containing modules for comparative assessment of efficiency and durability.

The comparative study was done in collaboration with SunPower Corporation under the Solar America Initiative. The study utilized 15 kilowatts of SunPower mono-crystalline matrices that were encapsulated with the Dow Corning® PV-6100 Cell Encapsulant series, and 15 kilowatts of SunPower mono-crystalline EVA encapsulated modules using identical cell and glass technology.

Both sets of modules were installed side by side in a 30 kW PV array at the Dow Corning corporate headquarters in Auburn, Michigan in July of 2009. The silicone-encapsulated PV modules for this array were produced at Dow Corning’s Solar Solutions Application Center in Freeland, MI USA.

2. Silicone Encapsulant Efficiecny Gain

Figure 2: EVA UV cut off of Solar Spectrum

To expand this demonstration of the silicone advantage, a collaborative study was started with Australia National University. In this study, the optical properties of silicone and EVA were measured and utilized in a Ray Tracing Simulation created by ANU. The basis of the simulation software is shown in Figure 3.

The study of silicone as encapsulants in PV modules has been underway for decades in arrays that have been installed at BP Solar, formerly Solarex, in Frederick, Maryland, USA and at Georgetown University in Washington, D.C., USA. These arrays have been successful at showing the durability of silicone encapsulated modules, but no study has been done to compare module efficiency gains of silicone encapsulation over EVA modules.

The study of silicones potential efficiency gains has been reported by comparing the percent of light transmission of silicones and EVA versus wavelength. From the graph shown in Figure 1, it was quite apparent that silicones were significantly more transparent over the range of 250 to 400 nm.

Figure 3: ANU Ray Trace Modeling of Optical Loss Mechanisms in crystalline PV Modules3.

The model combined External Quantum Efficiency Data for cells and the optical properties of silicone to generate a simulation of Jsc losses over the spectrum functional for crystalline PV cells. This analysis confirmed the observation of EVA cutting off the UV portion of the spectrum. The output of the analysis is shown in Figure 4.

Figure 1: Comparison of Silicone and EVA Percent Light Transmission from 200 to 800 nm Figure 4: PV module Ray Trace Modeling Results a) EVA optical losses b) Silicone Optical losses 4 a)

When comparing this data to the solar spectrum it was apparent that the EVA was cutting off approximately 3% of the useable spectrum for crystalline PV solar as shown in Figure 2.

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35

4 B)

were then installed at a site on the grounds of Dow Corning’s Corporate Center in Auburn, Michigan, USA in July of 2009.

The array was erected in two halves in same location, at a 45o angle with no shading. The east half (EVA): Inv #1: 4x9 modules; Inv #2: 4x8 modules. The west half (Si): Inv #3: 4x8 modules; Inv #4: 4x9 modules. Shown in Figures 6 and 7.

Figure 6: 30 Kw Array at Dow Corning Corporation, Auburn, Michigan, USA

The losses shown in the model output show a significant absorption of the available light below 400 nm for EVA with most other optical losses being equal. This information coupled with the External Quantum Efficiency data for mono-crystalline cells indicated a >1% relative gain in cell efficiency1.

An experiment to confirm the potential efficiency gains was conducted at a single cell level with SunPower Corporation under the NREL PVMR&D program. The results of this study, demonstrated under flash testing at STC, that cells encapsulated with silicone had ~ 1.7% advantage in Jsc losses when utilizing non-Anti Reflective (AR) coated glass and ~1.5% when using AR coated glass1.

3. Outdoor Array Silicone To Eva Comparison Armed with the confidence from the simulations and actual cell measurements, a decision was made to demonstrate these gains in an outdoor, large scale array. This array was constructed in collaboration with SunPower Corporation. SunPower supplied completed EVA modules along with 72 cell matrices (unencapsulated), glass, frames and junction boxes.

Dow Corning encapsulated the matrices with PV-6100 Cell Encapsulant Series on the pilot line located in Freeland, Michigan, USA shown in Figure 5.

Figure 7: Fronius Inverters for power collection and performance monitoring

The strings were coupled with 4 Fronius 7.5 Kw inverters. The Fronius data acquisition software was used for data collection.

Figure 5: Dow Corning® PV-6100 Cell Encapsulant Series Module Assembly Pilot Line Freeland, Michigan, USA

The modules were then characterized by IV using a Spire 4600 Sunsimulator and Electroluminescence (EL) for total power output and production quality.

Comparison of the Pmax of the modules indicated a lower power output for the silicone encapsulated modules at an average of 220.4 watts vs. 222.6 watts for EVA. Since the cells were chosen for similar performance this difference was determined to be caused by matrix damage due to shipping and handling by EL analysis. To correct for this discrepancy, the analysis of the array power output was conducted on a W/Wp basis. Once characterized, the modules 36

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The installation was completed in July 2009. The system was brought on line in September, and data acquisition started later that month. The arrays have been on line since that time and the modules have experienced temperatures from approximately 95o F to -10o F, and sun, rain and snow. Regular inspections have shown that the appearance of both Silicone and EVA modules continues to be very good.

The power output performance has been constantly monitored and regularly evaluated since September. The graph shown in Figure 8 is a summary of the comparison for the last year.

This data indicates consistent superior performance of the silicone array in kW/kWp performance in almost all weather conditions. There have been a few excursions of significantly greater performance of over 10% and some days of negative performance.

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Figure 8: Daily Power Output Comparison

These days are associated with very low insolation where the inverters are turning on and off throughout the day causing a large signal to noise ratio.

The average 30-day performance of the array is displayed continuously at Dow Corning Corporation.

Figure 9 shows a snap shot of the typical average performance at greater than 2% kW/kWp relative efficiency gain.

A closer analysis of a typical high insolation summer day for

Figure 10: Silicone vs. EVA High Insolation Summer Day (25June-2010)

4. CONCLUSIONS A 30 kW array to compare the performance of EVA to Silicone encapsulated modules was constructed at Dow Corning Corporation at the Corporate Center in Auburn, Michigan USA using EVA modules and matrices purchased from SunPower Corporation under the United States Department of Energy Solar America Initiative program.

The silicone modules were encapsulated using Dow Corning® PV-6100 Cell Encapsulant Series at Dow Corning’s pilot line in Freeland, Michigan, USA. The array was installed in July of 2009.

Data collection on the array has been underway from September 2009. The data collection has shown silicone encapsulated modules outperform EVA encapsulated modules at greater than 2% kWhr/ kWp relative efficiency gain. The modules have been exposed to all seasons experiencing temperatures from approximately 95o F to -10o F, and sun, rain and snow. Regular inspections have shown that the appearance of the Silicone and EVA modules continues to be very good. The array continues to be monitored for performance and appearance.

5. ACKNOWLEDGEMENTS Keith McIntosh and James Cumpston of Australia National University for silicone characterization and ray trace modeling.

Ann Norris and Nick Powell (Silicone characterization), Steve Crofoot, David C. Johnson, Craig Liberacki, Robert Oldinski, Kevin Houle, David Dobson, David Hoag, Anna Keeley, Scott Fleming and John Reed (Module assembly and characterization).Paul Blanke, Ted Murawski, Ray Garety (Array installation coordination and Data Collection). This material is based upon work supported by the Department of Energy under Award Number DE-FC3607GO17043.

“The information provided in this presentation does not constitute a contractual commitment by Dow Corning.

Figure 9: Summary Chart of array performance

Michigan day is shown in Figure 10.

This graph demonstrates that on this particular day the difference between silicone and EVA encapsulated modules is consistently between 1-2% kW/kWp relative efficiency gain once the insolation is greater than 100 W/m2.

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While Dow Corning does its best to assure that information contained in this presentation is accurate and fully up to date, Dow Corning does not guarantee or warranty the accuracy or completeness of information provided in this presentation. Dow Corning reserves the right to make improvements, corrections and/or changes to this presentation in the future. nnn

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Do You Really Know How Your Encapsulant Functions?

Lavandera- Antolín, Juan Diego; Cañon- Sanchez, Pamela Technical Department EVASA

Evasa is a young and enterprising company created in Spain, working in the plastic industry world with only one objective: provide encapsulant polymers for the photovoltaic industry. Years of researching and developing have led to three EVA based encapsulant perfect to fit the needs photovoltaic manufacturers offering them the best combination in the market regarding process time and technical characteristics.

What is an encapsulant?

It is a thermoplastic copolymer characterized by large atom chains bonded between them, which are able to relocate in several ways: filiform, tree, cyclic and even tridimensional configuration. Because of that polymer materials have special properties.

Polymers are compounded by chains linked between them by chemical bonds. A net is made up by the chains through the cross linking reaction. At room temperature, the polymer net avoids free molecular movements; it is because of that that polymers seem to be a solid mass, stiff and hard.

When polymers are heated, molecular organization could be modified by a constant pressure. Combining heat and pressure the polymer chains are prone to relocate themselves. When the heat stops and the material is cooling down the chains connect again as a net with the shape of the mould etc.

That is, thermoplastic polymers are compounded by monodimensional and filiform molecules, separated from one another. When temperature exceeds the polymer softening point, it is possible to model, to come back to a solid state when temperature decreases.

The polymer is able to repeat these cycles indefinitely, with the ageing as the only limit, which makes polymer stability worse.

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E VA S A is specialized in polymer handling and transformation.

Thanks to technology developed by ourselves we produce excellent industrial films, brand name S O L A R C A P. E VA S A E VA based encapsulants are chemically fo r m u l a t e d t o provide the best structural stability, because of that our encapsulants show:

Table 1. Light transmittance and yellowness index before and afert HAST ageing.

Table 2. Mechanical and adhesion properties before and after HAST ageing.

l H i g h

Gel content (>87%),

l

Excellent light transmission (>91%)

l

The best adhesion in the market

l

Zero shrinkage, so you can avoid cracked cells and optimize your costs.

l

Great UV protection

l

Photothermal stability

Laminating An Encapsulant. Getting The Best Results

D u r i n g p h o t ov o l t a i c m o d u l e manufacturing process it is necessary to analyze and control several parameters (temperatures, times, pressures…), visual tests are also important as easy and quick control. Bubbles and cracks or moved cells are an indication for problems with the encapsulant during the lamination process.

The shrinkage percentage of the encapsulant is determinant to avoid cracks and cells movement, therefore it is important to check this characteristic before choosing an encapsulant. Determining the shrinkage is not complicated and it is possible do the test

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only with a heating plate at 248ºF (120ºC) and putting the sample for three minutes on sand. The difference between the sample size before and after the test it is the material shrinkage.

starts. Therefore this is a phenomenon that occurs during all the lamination process.

In general, gel content rates higher than 75% implies an adhesion EVA – glass and EVA – Backsheet above 4 N/mm, so high gel content means high adhesion values.

Once a solar panel has been manufactured and its appearance is perfect, some test, besides gel content and adhesion, must be made in order to make sure the quality is perfect and the real module performance: l

Test in a climate chamber Figure 1. Percentage of Shrinkage of different commercial for reproducing weather encapsulants conditions are necessary to know the modules aging behavior.

Gel content rates after lamination are another important parameter that must be evaluated in order to determine the module quality and the adaptation grade between the encapsulant and the lamination cycle.

Gel content depends on the heating plate temperature and cycle time. On the other hand, heating time during vacuum process does not influence so much the final gel content. That means that cross linking reaction between polymer chains starts after a soft heating when the encapsulant reaches a high temperature, above 140ºF (60ºC) (encapsulant softening point).

Furthermore, it is necessary to achieve a good adhesion level. The adhesion values EVA-glass connection and EVA-backsheet connection, these are influenced by three parameters: plate temperature, vacuum time and pressure time. From the first moment that the encapsulant is under temperature a reaction that promotes adhesion between the encapsulant and the other components

l

Dump heat test (1000, 2000 or even 2500 hours) are conducted to determine the ability of the module to withstand the effects of long-term penetration of humidity. 185 ºF (85ºC) is the test temperature and the relative humidity is 85%.

l

Electrical performance must be checked before and after module aging.

l

Yellowness index determination. A yellowness, or even browning, of the encapsulant involves a fall of the solar panel performance. Because of that it is important that after test the module in the climate chamber the encapsulant remains transparent.

Yellowness index is another of the factors that we have to evaluate before choosing an encapsulant.

Why an encapsulant became yellow?

Figure 2. (a) Sideview of the layup of one typical module (b) Experimental cubes showing the parameter ranges for the lamination process. Source: 3S Solar Swiss System[1]

There are two differentiated process during polymer degradation: photooxidation and photoinitiation. During the photo-initiation the chromophore groups absorb the ultraviolet radiation generating excited states and free radicals.

Excited states are inter or intra molecular reactions of the radicals, which lead to a change in the physical properties of the polymers.

At the same time free radicals react with the oxygen molecules in the photo-oxidation, generating peroxy radicals (POO), and the photolysis of the peroxy compounds create POOH and carbonyl groups. The final result is a change in the encapsulant appearance and its colour. A correct formulation of the encapsulant (with the correct additives in the right quantities) avoids the yellowness and ensures the light transmission during all the photovoltaic module lifetime. [2].

Tables 1 and 2 show characteristics values of the main properties for EVASA encapsulants: high adhesion to glass and backsheet, both before and after aging, and a yellowness index very low combined with a high light transmission and good mechanical properties. All these properties together let us optimize lamination cycles making them shorter but maintaining gel content above 85%. Despite a good encapsulant is fundamental for obtaining a good quality solar panel and be able to work with short lamination cycles, EVASA has test (and are testing in new models) its encapsulants with the main laminator manufacturers. The principal objective of these tests is offer the best technical advises to our clients and adapt Solarcap encapsulants to module manufacturing lines.

Conclusion: Before choose an encapsulant there are some important properties to consider. On one hand it is important consider the encapsulant properties by itself: light transmission or shrinkage. On the other hand it is necessary study the behavior during the lamination process and the results: gel content, adhesion, yellowness or cycles times. If chosen encapsulant is not adequate lamination process may became really difficult and the module performance could be jeopardize.

EVASA takes care of every detail from the first step in the manufacturing to the delivery, fulfilling the most restrictive quality controls and standards: products UL listed, TÜV conformity (first worldwide encapsulant manufacturer with letter of conformity), ISO 9001 and ISO 14001 standards, protecting you inversion from the beginning to the end during all the module life. nnn

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Importance Of Adhesive Tapes In This PV Module Manufacturing Darshan.C.S.- SriVasavi Adhesive tapes Pvt Ltd,. Director Business Development, Bangalore

A

humble attempt has been made to highlight the importance of Adhesive Tapes in this PV Module

manufacturing. Adhesive tapes deserves equal importance viz a viz PV Cells, Back Sheets, Lamination Process, etc,.

Brief narration of all type of adhesive tapes with application has been done to benefit the manufacturer in choosing the adhesive tapes for their product and process.

Double sided foam tapes which are used for perimeter sealing (fixing of Aluminium frames to modules) should meet the technical requirements of IEC 61215 and IEC 61730, the criteria to be fulfilled are the damping test and the mechanical test as per the testing

PE Foam Tape PE Foam is mainly through extrusion technology. With three main processes i.

AFT is made with carefully blended

Mixing of Gas in molten PE ii .Expanding into a lot of small bubbles or cells iii. cooling the expanded PE , thereby creates the final foam.

acrylic adhesives which are extruded

In this process, the outcome will be of a low weight PE foams with small regular cells structure, these foams has a sound insulation, heat insulation and high shock absorbing capabilities, these foams will be corona treated for better adherence of adhesive on foam, A uniform layer of adhesive is coated on the foam on both sides using adhesive transfer coating, which is also called as reverse coating method.

processed to enhance specific features. AFT

guidelines.

Application 1

Frame Sealing Frame Sealing / Fixing is usually done by double sided foam tapes or Silicone Sealants.

To detail about double sided foam tapes, there are three variants

40Â

accurately to various thicknesses, though the appearance is like foam, it a injection of air bubbles and the glass beads, and further are not prone to internal splitting of material layers in comparison to the conventional PE or PU foam, more specific, the cohesive strength of acrylic foam is much greater than that of any other foam tapes.

Unique characteristics of AFTs are its visco elastic nature, strength, durability and ability to bond and seal., these are characteristics incomparable to other type of foam tapes available.

PU Foam Tapes Reaction between a disocyanate and a polyol, in the presence of a catalyst and materials for controlling the cell structure .

PU foam can be made in a different density and hardness by varying the monomer used.

This process is usually done in a controlled atmosphere.

These PU foams with the desired density will be subjected to corona treatment for

1.

PE Foam Tapes.

2.

PU Foam Tape

on both side by adhesive transfer coating

3.

Acrylic Foam Tapes.

process.

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Acrylic Foam Tape (AFT),

better adherence of adhesive, and coating

Silicone Sealants: Silicone sealants in uncured state normally looks like a thick gel, on exposure to air, the reactive end groups of the silicone polymer join with each other, releasing water and forming long polymer chains until the gel turns into elastic and relatively tough silicone rubber. There are different types of curing system like Acetoxy, Oxime, Alkoxy, Amine Acetone, Neutral cure.

When compounded correctly they

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are very stable, reliable with excellent adhesion and physical properties. And has very long term performance. Once cured their properties does not change, and they are resistive of any UV exposure.

Silicone Sealants were used for perimeter sealing application in modules , over the period of time, the advantages were recognised of using foam tapes over silicone sealants. foam tapes have scored over Sealants mainly on the curing time and cleaner & easy application.

Acrylic foam tapes have the ability to improve quality, productivity, workability.

Junction box mounting

AFT can handle any force exerted on it , and they last longer.

Added to the Frame sealing application, the tapes has other application such as Junction box and Cell Placement.

Application 2

Junction box Mounting, For Junction Box Mounting, Acrylic foam tapes or the PU/PE Foam tapes are used as die cuts (tapes die cut punched as per the junction box profile). Application of AFT will reduce the process considerably thereby giving more durable, reliable and less time consuming application method.

Acrylic Foam Tapes

Application 3

Cell Placement Clear transparent single sided/double sided Polyester tapes with silicone adhesive, clear transparency ensures that the tape is not visible after the lamination process. And also the tape will not change color even after exposure to direct sunlight (UV rays). These tapes helps the process by holding the cells in equal distance without any misplacement or alignment during lamination process.

Thus considering the criticality of application it is extremely important to choose

Frame Sealing (perimeter sealing)

right tape suitable for the application.

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UL Requirements for Polymers Applied in PV Module Assembly LI yinbai- Beijing TONSAN Adhesive Co., Ltd

The main contributions of the paper are as followings: the test methods of polymers applied in PV module assembly was introduced. The performance requirements of polymers applied in different places of PV modules was also introduced. The ways of how to design the format to make the polymers to suit the performance requirements of UL was expounded.

1 Preface Solar module industry is increasing at a striking rate. In order to ensure the quality of components and the personal safety, both the United States and Europe develop a series of standards to regulate this industry, and UL is one of the most essential criterions in PV area. It is the â&#x20AC;&#x153;passportâ&#x20AC;? of the US market. Organic silicon as an important part of PV module packaging materials also needs the UL certification. This article introduces the UL standards and test items related to packaging materials and explain the requirements of different locations where need the silicon, and will declare the special requirement of UL to the locations.

Relative thermal index shortform is RTI. It is to evaluate the maximum temperature that can maintain the performance of polymeric materials more than 50% after used by 10 million hours. 10 million hours is equal to approximate 11 years, so commonly

temperature of 50% performance degradation after 10 million hours, is the RTI, shown in Figure 1. Even with this linear regression method, the entire testing process needs about 1-1.5 years. RTI is an evaluation of anti-aging properties and the higher the RTI

used in the certification process 40-70 degrees higher than the RTI temperature, to test the material properties under different temperatures to get the attenuation curve.

Then according to the Arrhenius linear regression formulation to calculate the

the better the aging-resistance performance of the material. RTI is an evaluation of antiaging properties of materials index, RTI higher the value, the better the anti-aging properties of materials. The main chain of silicone rubber is polydimethylsiloxane, and

2 Basic test items of UL UL is a non-governmental institution engaged in safety certification, and involved in many test items. The tests which are related to polymer materials for PV module testing are mainly the following.

2.1 Relative thermal index 42Â

EQ INTERNATIONAL November/December 11

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bond energy of silicon-oxygen bond can reach 460J/mol, so it has good aging-resistance performance.

2.2 Comparative tracking index Comparative tracking index shortform is CTI. When it is raining, sometimes there might be a spark between electrodes on the telegraph pole because of water. The polymer material will be carbonized under the electric spark function and will form the permanent electric conduction channel, is equal to shortcircuits between two posts.

CTI is to appraise if the surface of the material is easy or not to create the electric conduction channel. The concrete test method of UL is shown in Figure 2. Apply a certain voltage between two electrodes and then drop 0.1% NH4Cl solution between the two electrodes at the rate of 2 drops per minute.

If the current between the two electrodes gets 0.5A and maintain over 2s, we consider that the material surface has already formed the electric conduction channel. Record the voltage and the drops of solution, then makes the different voltage and the ammonium chloride solution drop number curve. Find the voltage in the curve corresponding with 50 drops and that is the CTI value. The higher the CTI value, the weaker the ability to form the electric conduction channel of the insulation material. According to the optimization design, the PLC class of Tonsan silicon is 0.

mainly includes two test methods: horizontal burning test and vertical burning test.

Horizontal burning is to fix the specimen horizontal, ignite it and test the combustion velocity and whether extinguishable or not as shown in Figure 3.

Vertical burning is to fix the specimen vertical, ignite it and test the combustion velocity and if there is combustible substance depreciation, as shown in Figure 4. During the procedure, the flam under the bottom of the sample will heat the sample, and it will

2.5 Hot wire ignition Hot wire ignition is short for HWI. If the electric circuit has been shorted, the wire will be used as electric stove wire and the temperature will be approximate 7008000C, and such high temperature will ignite polymer material. HWI is to simulate the extreme case and test how long it will take to burn, shown as in Figure 6. According to the optimization of formula, HWI performance level category of Tonsan 1527 and 1521 can get to level 2, which means it will take more than 30s to ignite.

Figure 4. Vertical burning

be more advantageous to combustion. So the request of vertical burning is harsher than horizontal burning.

2.4 High current arc resistance to ignition

2.3 Burning test Burning test is to check weather the material can be ignited, if fire can be extinguished or not, and what is the burning rate. According to the UL94, burning test

that is arc. In the center of the arc, the temperature is about 4000-50000C and such a high temperature will certainly have adverse effect or even ignite the polymer materials. HAI is to value the capacity that the polymer material resists ignition caused by arc. Shown as in Figure 5, the current between the two electrodes is 33A and move one of the electrodes evenly. Make sure it creates 40 arcs per minute and record how many arcs will ignite or break the material.

According to the optimization of the formula, the performance level category of HAI of 1527 can reach 0, which means it will not be ignited or broken after 120 arcs.

High current arc resistance to ignition is short for HAI. When the switch is cut down, sometime there will be electric shock discharge between the contacts and

3 Positions of silicon application Recently, there are normally four positions on PV module needing silicon adhesives.

3.1 Sealant for frame sealing Framing sealant is used to bond lamination and aluminum frame and need to satisfy the following requirements. It needs to have good bonding performance with lowiron glass, back sheet and alloy frame. During the using process of module, module maybe affect by wind load rain and snow load. Both lamination and alloy are rigid materials, and need adhesive as elastic material between them to release the effect of the alternating load. PV module is used outside and need to have good aging resistance performance.

At last, the frame sealant also needs to have good compatibility with each material used in PV module.

3.2 Adhesive for Junction box bonding

Figure 3. Horizontal burning

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Junction box adhesive is used to bonding junction box and back sheet, so it needs to have good bonding strength and tearing

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temperature of the junction box should be at least 400C+200C=600C. The RTI of silicon is 1050C, can totally satisfy the UL requirements to framing adhesive. While RTI of MS and PU is only 500C and cannot satisfy UL requirements.

4.2 Adhesive for Junction box bonding UL requirements for junction box bonder are similar to frame sealant. RTI index shall be 200C higher than the maximum temperature of modules temperature tests.

4.3 Junction box potting material Figure 5. HAI

resistance property. It is also used outside, so needs good aging resistance performance.

3.3 Junction box potting material The junction box interior has some narrow space so the adhesive needs good fluidity to fill the whole space in the box.

Usually, the potting adhesive has two components; therefore it needs to have certain operating time and relative short gelling time. As the junction is small and the contact distance is quite small, the adhesive need good insulation performance. The bypass diodes in the junction box will create massive heat during working. If the quantity of heat cannot be dissipated in time, it will have the risk of burn up the bypass diode. By the using of Tonsan potting adhesive can highly reduce the temperature of bypass diodes, and enhance the security reliability greatly.

3.4 Sealants for Ribbon sealing The module assembling factory genera dispense two tapes of adhesive at both sides of the ribbon. If the viscosity is excessively high, there will be gap between the two

tapes of adhesive; if the viscosity is too low, it will cause partial lack of adhesive due to incline during the transporting process.

So the ribbon adhesive should have a quite appropriate viscosity. Similarly, the ribbon adhesive contact with electric and should have good insulation performance.

4 UL requirements to different adhesives The adhesives used in different positions in PV module are not the same so the requirements of UL are different.

4.1 Sealant for frame sealing The requirement of UL to framing is the that RTI should be at least 20 0C higher than the maximum temperature of the module. UL1703 prescribes that, under 400C ambient temperature 100mW/ cm2 radiant and less than 1 m/sec wind speed, test the temperatures of different points.

When the module is working, the surface temperature will increase. Even do not think about the temperature rising, the required

Figure 6. HWI

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Junction box potting sealant is contacted with electrics, so it requires higher UL requirements. The requirement of RTI is the same as before, but part of cells will be sheltered during temperature tests, so temperature inside junction box will be very high which require materials with higher RTI. After potted with TONSAN 1521, the temperature inside junction box can be reduced and also the flaming risk will be reduced.

Besides RTI requirements, UL also require CTIâ&#x2030;Ľ2 for materials that contact with electrified body.

UL has no specific requirements of flame resistance, HB,V2,V1,V0 are all qualified, but different flame resistance rate correspond with different HAI and HWI, higher flame resistance rate, lower HAI requirement.

4.4 Sealants for Ribbon sealing Ribbon is also contacted with electrified parts, so the requirements are as the same as potting sealants.

5 Conclusion As an outdoor arranged power generator, PV modules shall fulfill relative UL performance and safety requirements.

As a important part of PV modules, the performance of silicone sealants can effect the whole performance of PV module, so to make PV modules UL certified, we have make different formula and design according to different requirements of application places. TONSAN 1527 and 1521 are designed and developed according to the requirements of PV modules, they are UL certified and their performance can fully satisfy the requirements of PV modules. After putting into market, TONSAN PV sealants are adopted by most customers and module factories, and we possess about 70% market share for a long time.

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Reliability and Durability of PV Modules

Rajnikanth Umakanthan Business Head â&#x20AC;&#x201C; India & MEA Chemicals I Energy I Wire & Cable

O

ne of the major concerns impacting the acceptance of Solar Power as an alternative source of energy globally has been the reliability and durability of PV Modules. PV Modules have been observed to fail prematurely in real world field installations and laboratory test conditions.

Also the power output from PV Modules exhibit a tendency to deteriorate over period of time.

in degradation of output power.Durability involves the route to failure (mechanisms), the property rate of change(kinetics), degree of robustness etc. These may not cause

Ethylene Vinyl Acetate ( EVA ) which is used as an encapsulant , Poly Vinyl Fluoride and TPT material used as back sheet to provide mechanical support, Silicone Sealants used

failure but result in declining performance and shortened service lifetimes for PV Modules.

as a sealing compound, potting material or adhesive etc., These polymeric material have a tendency to deteriorate when exposed to the elements of nature which in turn impacts the performance of a PV Module. The reliability and durability of a PV Module is negative impacted by the following environmental

High initial investment and longer payback period required for Solar PV makes it even more important that the PV Modules, the heart of a PV system work for a longer period of time and at the same time maintain a higher level of performance.

Some new technologies in PV like Thin Film and Concentrated Photovoltaic have a very short history and make it more challenging to forecast their future performance in terms of reliability and durability.

Reliability is the duration or probability of failure free performance of PV Modules under stated conditions. Reliability is also defined as time to failure, a point at which the module ceases to work. Durability is the loss of desirable or required properties of the PV module over a period of time resulting 46Â

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PV Modules use a lot of polymeric material in their construction. Some of the most commonly used polymeric material are

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factors. l Temperature – Very low temperature towards the poles and very high temperature towards the equator and wide intra-day variance in desert region etc., l Humidity – High humidity in tropical regions. l

Salinity - High Salinity in coastal regions.

l UV Radiation – polymers are impacted by incidence of UV rays. l Mechanical Load – High wind conditions / Snow Loading in cold regions.

Several leading test laboratories and research organisations are working on developing a test plan that could simulate the real world conditions that a PV Module would be subjected to during its service lifetime and the impact various environmental factors might have on their reliability and durability. However the modeling has proven to be quite challenging due to the numerous factors influencing the performance of a PV module and the complexity introduced by their simultaneous incidence on the PV module. The same module would be subjected to a different environmental condition if installed in a tropical region compared to a desert region, coastal region or polar region.

The above factors make it very difficult to predict the actual lifetime of the PV Module ( Reliability ) or the power output degradation ( durability ) which are critical to estimate the pay-back period for a PV System. One approach is to subject the PV modules to higher levels of environmental conditioning than what is prescribed by the IEC standard for Module Design Qualification and Type Approval. The ability of the PV Module to survive higher levels of environmental conditioning tests like Damp Heat, Temperature Cycling, UV Exposure or Humidity Freeze etc., could provide higher level of confidence regarding its reliability and durability though it would still be difficult to quantify the actual number of years for which the module would work or to predict the power output after 10, 15 and 20 years. Another approach is to explore the correlation between the degradation of individual component ( EVA, TPT, Tape etc.,) properties and module failure modes.

This approach explores the effect of major aging factor(s) (UV, Temperature, Humidity) and their contribution(s) to durability/reliability and safety hazards as a function of aging time, exposure time/intensity. This helps establish the understanding of failure modes and mechanisms and durability/reliability of long-term environmental exposure for polymeric materials used in PV system.

Today in the absence of a clearly defined mathematical model to predict the reliability and durability of PV Modules the finance community and project developers would need to rely on the above results to make an informed decision on the choice of PV Modules to be used in their system.

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Solar glass

Solar Cells

Aluminium Frames

Sealants

DAKSH ENERGY SYSTEMS HO : #95/W, Annupuram, ECIL Post, Hyd- 62, A P, India

Mobile : +91 98853 29900 Skype : naveenbali90 E-mail : dakshenergy@yahoo.co.in

solarindia www.solarindia.net EQ INTERNATIONAL November/December 11

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SO L A R ENERGY

Chhattisgarh Investment Limited2MW PV Plant By Vikram Solar Samujjal Ganguly, General Manager Marketing -Vikram Solar Pvt Ltd

Chhattisgarh Investment Limited

Chhattisgarh Investment Limited is the project developer of this 2MW grid connected Solar Power Plant under the IREDA (Indian Renewable Energy Development Agency)

PV Module Installation Structure

•

48

The power plant is set up in Kharora which is around 38K.M from Raipur city.

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The is site is well connected through the state high way and the nearest railway station in Tilda. A clear uneven area of 11 acres was handed over to us in the month of April 2011. As soon as the land was handed over to us, we started our ground work of leveling the plot and parallel our Engineering team started designing different component of the Power Plant.

• After the complete development of the land which took around 20 days, we started with the land making and then with the civil work for the foundation of Module Mounting Structure which involve work like soil excavation, making, leveling and concrete work.

•

As the monsoon was fast approaching we had to put extra effort to complete as

•

Specially designed Module Mounting structure were imported and installation started after foundation marking, assembling of different components etc.

This took nearly 25 days to complete the whole process. Simultaneously we started with module wiring and laying of the cable from different string of modules to string combiner Box and then to the Inverters in the control room.

•

Unfortunately Chhattisgarh was severely hit by flood in the month of August in which we faced several problems as the site was completely flooded and was isolated from all basic need required for us to complete the project.

•

Despite problems like no movement of man, materials and machine we put enormous effort to put everything back in righ track. As the flood situation improved we took several jobs in the same period of time like installation of different component and sub component of the Solar Power plant I.e. installation

Control Room with Transformer

Array of PV Module Installation

much as civil work before the monsoon and we were able to complete the work as per schedule of 2 months.

of 8nos. 250kva inverters, 4 nos. of 630 kva Transformers & 1 no. VCB Kiosk.

The plant was successfully commissioned

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in the month of October 2011. We are extremely happy as the achieved result of generation of the Solar Power plant is more than the expected value.

Vikram provide its clients and investors:

Our Normal Project Time Sheet: Secret of Success: Major reasons for the company’s success is due to its wide experience, Long terms

Vikram Solar Private Limited is

•

a fixed completion date

one of the companies to foresee the

•

a fixed project cost

opportunities which serve both the areas

•

no or limited technology risk

of business development and generation

•

performance guarantees

of green energy to reduce the carbon foot

•

liquidate damages for both delay and performance

print of mother earth.

Over the years, Vikram’s R& D team has developed and perfected our modules ranging from 3wp to 350wp. The module goes under

•

The first step was to setup a manufacturing facility of 50MW capacity per annum, in the eastern part of the country to manufacture Solar Modules of European standard.

•

The second step started with acquiring the knowhow for setting up Megawatt scale projects on EPC mode.

Vikram solar has very successfully

commissioned many projects across globe. At the moment we are involved with around 30MW project in states like Gujarat, Uttarakhand, Orissa, Rajasthan and Utter Pradesh.

We bagged our first solar Megawatt level project in Chhattisgarh, India

(Stages towards completion of a project)

suppliers and technology tie ups, In house R& D Team and last but not the least our state of art in-house module manufacturing facility.

during the month of August 2011 and

rigorous quality check under their supervision and thus we are able to give our clients and investors a peace of mind and security.

fortunately we became the first company get synchronized to the Grid there.

Generation of CIL:

8 numbers of 250kva grid connected Inverters have been used of AEG make.

4 numbers of 630kva outdoor type transformers have been used of Electrotherm make.

The MMS have been imported from Spain and is of Proener make.

The VCB was of ABB make.

The designing of the entire plant was supported by Proener, Spain.

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SO L A R ENERGY

Performance of Solairedirect’s First Solar Park:

VINON-SUR-VERDON – 4.2MWp Gaurav Sood, Managing Director-Solaire Direct India

Solairedirect SA (“SD”) is one of the leading integrated French solar power producers and specialises in the development, design, engineering, financing, construction, ownership and operation of solar photovoltaic (“PV”) power generation plants, including the manufacture of PV modules.

The company has about 120 MWp Solar PV projects (as solar parks and rooftops) under operation & construction. The company was founded in 2006, has over 300 employees worldwide and had an annual turnover of €70 million in 2009 and €160 million in 2010.

S

D was founded by a group of energy industry experts with a broad spectrum of skills ranging from Industry Management, Investment & Finance, Business Development & Marketing, PV System Engineering, Design, Development and PV Module manufacturing.

Given that the cost of the PV modules makes up approximately 70% of the total capital cost of a typical solar park, it is clear that control over this element of any solar park project is critical to its on-time, on-cost, completion. For this reason the company took the decision, in 2008, to establish their own manufacturing facility. Solairedirect Technologies (Pty) Ltd (“SDT”) is a wholly owned subsidiary of SD and is located in Cape Town, South Africa. The plant was commissioned in early 2009 and is capable of producing 35MW of solar PV modules per annum, with the ability to increase output to a maximum of +/- 100MW per annum. SD is the first French company and tenth globally whose modules have been insured by Munich Re for performance warranty.

In June 2010, by the combination of a reforming commercial and regulatory environment in India and the abundant 50

EQ INTERNATIONAL November/December 11

natural resources available, Solairedirect founded Solairedirect Energy India Pvt. Ltd (“SDI”) headed by Gaurav Sood, Managing Director. Solairedirect also has subsidiaries in Southern Africa, Chile, Morocco, Malaysia and Thailand.

Sood says SD completed the construction of its first solar park in France in early 2009.

Located close to the village of Vinon-surVerdon, the solar park has a peak generating capacity of 4.2MWp. In the same year SD started the first construction phase of the largest solar park project in France at that time. Les Mees 1&2 are two co-located solar parks of 12MWp each, giving a combined peak generating capacity of 24MWp. The construction of Les Mees 1 was completed in early 2010 and Les Mees 2 was completed in December 2010. SD started to build 3 new parks, Esparron 1 & 2 and Saint-Hilaire in 2010, adding a further 20MWp to the generation portfolio. SD has just finished building of 7 parks in S2 2011 adding 45 MWp. VINON-SUR-VERDON is Solairedirect’s first solar park with a capacity of 4.2 MW which started its operation on 1st March 2009. This park was built on 9-hectare land

in a location with little natural or farming value, was designed with an architectural and landscaping vision. The facility is designed to be compatible with items such as grazing, plants cultivation, and species suited to the local biotope. Vegetal earth was preserved during the site’s excavation in order to sustain biodiversity. This project was built according to a strict sustainable development approach, unprecedented in France.

VINON-SUR-VERDON solar park uses crystalline silicon technology modules of capacity 240Wp covering 3 hectares of land with 18,960 modules of Yingli which are fixed on aluminium structures. The foundations are made of metal screws which facilitate the decommissioning of the facility and its ultimate recycling.

Technical specifications of electrical

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remote location through high definition cameras.

The entire park is totally unmanned and has electrical fencing to avoid any intrusion.

equipments are defined by Solairedirect’s engineers. They select and qualify equipment suppliers based not only on their ability to deliver high-quality, high-performance products but also considering their ability to provide reliable maintenance services.

In particular, Solairedirect seeks partners that guarantee high technical availability levels.

VINON-SUR-VERDON solar park uses Inverters and other electrical system of Xantrex make which has high reliability and performance. Inverters are equipped with a MPPT module (Maximum Power Point Tracker) that targets and settles the power point to the maximum of the PV generator.

The graph above compares the radiation measured on site with the forecast of the financing plan. Meteonorm irradiance is given for indication.

2. ELECTRICITY PRODUCTION Average Performance Ratio achieved till date is above 83 % with the technical availability of more than 99%. VINONSUR-VERDON solar park saves 2800 tons of C02 annually”.

Symmetry monitor are used to continuously compares electrical current input on each branch and triggers an alarm in case of relative disequilibrium between the branches.

Data analysis is performed using an algorithm that compares present against historical values and automatically triggers the error signal should discrepancies reach certain levels.

The hundreds of measuring points inside the converters enable the operator to collect real time data on the generator and facilitate maintenance. Our equipment includes a data recovery system that records the evolution of operational parameters as measured by the converters and that can be accessed either locally or offsite with a PC. Recorded data are immediately collected and managed in user-friendly, detailed reports and tables for facilitate analysis. In fact, the system is a comprehensive SCADA (Supervision Control & Data Acquisition) platform that enables the operator to virtually control plant management off site.

“VINON-SURVERDON solar park till May 2011 has generated energy of 14,925 MWh and has generated revenue of 4,850 K€.

The chart above shows actual production compared to estimates of the financing plan “Base Case”.

3.

PERFORMANCE RATIO

The chart above shows the performance indicators since commissioning. The performance ratio is computed every month since commissioning.

4. TECHNICAL AVAILABILITY

Average insolation Gi (in kWh/m2) is measured via probes that are installed atop solar arrays and positioned to avoid surfaces where inter-row shadows may be cast.

1. SOLAR IRRADIATION This park also has weather station which records climatic data and are linked to data logger which helps in comparing the parameters of the solar park.

VINON-SUR-VERDON solar park also has the facility to see the site from

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The figure above reflects the overall technical availability of the equipment monthly and cumulatively since the commissioning.

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SO L A R ENERGY

3.2MW_Solarpark Duben Germany

Thomas Sandner

Munjal Rangwala

German Expertise Coupled With Indian Engineering : Receipe for Perfect PV Plant in India Thomas Sandner, CEO Abakus Solar AG Munjal Rangwala, CEO Harsha Abakus Solar Pvt. Ltd.

EQ : Please enlighten us on the JV between Harsha and Abakus, Individual Group Strengths, Vision, Strategy for India etc…

Thomas : abakus solar has a strong background in the PV industry due to its long history in the field of PV application.

Beside sophisticated experience a wide network over the whole value chain has been established during the years. Harsha Engineers is an established company in India with a very good know-how in mechanical engineering and a strong position for local business in India due to its high qualified and international management and personnel.

Therefore the JV can go back to a very strong engineering team with a long and comprehensive experience in the PV field and a wide range of products with proven technology. Harsh abakus solar can offer a suitable solution for each individual project and customer with a very high quality and reliability due to our awareness of key issues for successful and long-lasting PV projects.

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Munjal: Harsha Abakus Solar is a

also plans to expand its existing footprints

joint venture between Harsha Engineers

in the high growth segments such as the

and Abakus Solar AG. Harsha Engineers is

Building Integrated Photovoltaic (BIPV)

four decade old engineering group based out

and off-grid applications.

of Ahmedabad. Harsha Engineers started their solar energy division in the year 2008 bringing strong engineering and execution skills, in addition to in-depth understanding of the Indian renewable energy market. On the other hand Abakus Solar AG is a solar industry pioneer in Photovoltaic applications worldwide and has been operating since last 17 years in this field. Abakus Solar brings in long-standing and well-established access to clients, direct links to production capacities and one-stop project realization know-how.

Harsha-Abakus Solar, therefore jointly,

Ultimately we aim to provide renewable energy in the mainstream and make it as an option to masses as a source of power. We also aim to decentralize the power generation and supply so as to bring in greater efficiency and thereby empower the society with cleaner and eco friendly energy solutions.

EQ : What are the experiences and learning’s from Germany for constructing a solar farm. How do you think India is a different market than Germany and rest of Europe ?

brings more value addition to the Indian Solar

Thomas : Germany is the most

Photovoltaic market by playing a prominent

established market for grid connected PV

role as an end-to-end system integration

systems in particular with more than 20

solution provider. The Company’s key focus

years of experience and an installed capacity

areas are grid-tied power plants on either

of over 20 GW. During the recent years the

free-field or rooftop. Harsha Abakus Solar

size of PV installation has shown a trend to

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bigger PV installations as MW scaled solar farms. Companies like abakus solar have been used to build systems with high quality on the one hand but in a very efficient and cost-optimized way on the other hand due to the high competitive market in Germany.

Harsha abakus solar can bring along technical capacity in the field of large scaled solar farm projects. The difference between the market in India and Europe are currently caused by the project development, e.g. permissions, license procedure and financing issues.

The grid implementation will be another difference and challenge at the same time in the long run perspective because of the difference in the existing or non-existing grid topology and distribution.

EQ : Please enlighten us on the projects executed and germany and in pipeline in Germany, Europe and India?

Thomas: abakus solar have a long track record of projects from small stand-alone systems up to MW sized solar farms in Europe but also single projects in SouthEast-Asia, West-Africa and North-America.

A 10 MW solar farm has been completed presently and we are working on several multi MW projects in mainly in Italy but also in Germany, Africa and India as well.

Beside solar farm activities abakus solar can show a lot of experience in all kind of roof-top installations up to MW sized PV systems. For more information please visit: http://www.abakus-solar.com/en/references. html where you can download some detailed information about selected projects.

Munjal: In India we are executing two MW scale projects which are located in Gujarat apart from several KW scale projects. Our Gujarat projects are of 1 MW and 5 MW and they are located near Tarapur and Surat respectively. We have partnered with several companies for upcoming projects in Gujarat and Rajasthan for phase 1 batch 2 of JNNSM.

EQ : Please enlighten us on the experience of working with different technologies (c-si vs. Thin Film, Fixed vs. Tracking, String

vs.Central Inverter ec..etc…) Whats the ideal solution for India and why?

Thomas: We are always looking for the best solution in respect of the local conditions and requirements in the sense of the customer.

Every single circumstance has to be noted to develop the best solution and therefore we will not promote any patent remedy for a solar system. Due to the quick changes in the PV industry during the recent years and months every recommendation must consider individual aspects and present conditions.

Harsha abakus solar can offer all kind of technologies and can bring along experience with different systems and products which will enable us to design an individual solution case by case. We realized a 1 MW solar farm with c-si and thin-film recently which will deliver some proven results about the advantages and disadvantages of these technologies in the region around Ahmedabad in the new future.

Munjal: As Thomas mentioned, selection of technology depends on several macro and micro factors such as location, land available, direct solar irradiation available etc. Also constantly change in pricing of different technologies is big factor in the decision making of the project developer. In some areas Thin Film offer better output in higher temperature because of their inherent characteristics but tend to have more Balance of System costs. So every single factor is counted before making any decision.

EQ : What do you expect the outcome of bidding at the Batch II of Phase I of JNNSM and comment on the viability of the projects.

What are your expectations?

Munjal :As the Indian solar PV market enters its 2nd year, since implementation of JNNSM, after realizing and factoring in the ground realities, we expect even more competition under batch-II as compared to batch-I. We therefore, would see a lot of big-ticket players scouting for a sizable chunk of the allotted 350 MW capacity under batch-II bidding.

3MW_Solarpark_Hungen www.EQMagLive.com

In terms of viability, we see projects would make more commercial sense, as compared to batch-I, due to sharp reduction in capital cost; say about 25-30% over a period of one year. On the other hand, reduction in feed-in-tariff is only about 14%, during the same period. So, if we foresee a similar pattern in discounts offered, on feed-in-tariff, as it was in phase-I, project developers, with sizable profit-making existing business, can expect attractive returns/cash-flows on their investments.

EQ : Whats your view on the Indian Policy Framework and one piece of advise you would like to give to the government?

Munjal : In my view various governments bodies whether it is Federal Government ( JNNSM) or State government ( Gujarat, Rajasthan etc.) have done a great job of identifying needs and pushing solar industry in India. Of course there are a lot of things to learn from Phase 1 and I think both industry and the government have taken note of that. Having said that I would like to advise government to take holistic approach regarding solar manufacturing and also push KW scale or rooftop system in coming year as that’s where we can really take advantage of solar energy in India.

EQ : How has falling modules prices affected the EPC Business in positive and negative manner?

Munjal: Falling module prices have made solar projects more viable not only for investors but solar applications and rooftops as well. It has made sure that we reach grid parity sooner than later. Also this has created a bigger bottleneck for module manufacturer and EPC companies as project developers are not willing to settle on a particular price and this is causing a lot of delays in project.

We have to avoid the mistake of taking this drastic decrease in module pricing as a norm as there are several reasons for it such as inventories, consolidation, oversupply etc. This also has created a sharp focus on Balance of System cost and that is great news for EPC companies, such us ours, as that is where we are able to add value.

EQ INTERNATIONAL November/December 11 10 KW Patan India

53

1 MW Tarapur India

EQ : What area the brands with which you generally prefer to work and detailed reasons?

get the most optimized solution for their

Munjal: We prefer to work with companies which offer quality solutions at a competitive price. This is where we are able to leverage Abakus Solarâ&#x20AC;&#x2122;s experience of more than 17 years in solar PV industry.

They have worked with several module and inverter companies and have a useful on-field experience about quality and long lasting products. Our goal is to work with bankable partners as we are giving solutions which are going to work for more than 25 years. Also we prefer to work with our inverter and module partner with long term association in mind as it provides trust, stability and it enables two way communications to improve products in general. On module side we prefer to work with companies such as Nexpower, AUO, DelSolar, Abound, Vikram and on inverter side SMA, AEG and ABB. We have our own support structure solutions for rooftop and free field but we extensively work with Schletter in Germany for rooftop solutions.

so they can get best possible output.

investment. We also propose options in module and inverter based on their project locations For each project, we conduct in-depth weather analysis using premier third-party agencies like 3-tier, we perform rigorous permutations and combinations to select the best suitable technology solution and our team relentlessly works towards developing a right execution philosophy to optimize the return on investment, for our clients.

Also we extensively work with our component suppliers so that we can offer our customer latest and technologically most advanced product. We have worked with these suppliers for many years so they also know that we offer quality solutions and help us maintain solar plant for many years.

With help of Abakus Solar we have developed quality check and installation best practices and adapted them to local Indian conditions. This offers seamless execution of the project by avoiding many unforeseen circumstances during installation

EQ : Can you please enlighten us on the way you implement a project and what specific or unique things are followed which makes you different from other EPC Players?

and commissioning. We also have many years

Munjal: Right from when a customer approaches us for solar PV project, we guide them in every aspect of the project so they

EQ : Please tell us about the team strengths and resources developed in order to offer your EPC Services?

54Â

EQ INTERNATIONAL November/December 11

of experience in Operation & Maintenance in solar PV projects which enables us to offer best plant output at minimal cost.

Thomas: We can offer a wide range of services for PV systems starting from feasibility studies, yield estimations, due diligence, engineering and design, supervision and site inspection, installation and performance check, operation and maintenance and turnkey-solutions as EPC contractor. Harsha abakus solar can go back to a team of engineers in Germany with experience of up to 30 years in the PV industry and can bring along an increasing local team which has been trained and supported by abakus solar in Germany and reference projects in India as well.

Munjal: Harsha Abakus solar believes in quality, training and hands on experience.

Even before our joint venture started we sent our project managers and engineers to Germany for training and working experience in large scale solar PV power plants. We have assembled a great team which has project experience of more than two MW scale PV power plant execution. Also we have carefully selected contractors who have worked on various solar projects or at least one solar project with us. This creates a trust and contractors also know our quality standards and procedures. We are taking help of our German counterparts to develop quality check, execution process, commissioning process etc. specific to Indian market. We have project engineers coming from Abakus Solar to commission first few project and provide guidance to our local team.

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EQ INTERNATIONAL November/December 11

55

I NT ERV I EW

One on One with Mr. Vish Palekar,

CEO & Business Head, Cleantech Ventures, Mahindra Partners at Solarcon India 2011 “75 kWp Rooftop project in a commercial complex of a SEZ in Chennai”

Emerging Indian EPC Expertise amongst the Indian Conglomerates EQ : Please enlighten us on the evolving Solar Business within the Mahindra Group?

VP : The Mahindra group is bullish on solar as well as the entire Cleantech and Sustainability space. Our commitment towards Cleantech is visible with the investment in the Indian Electric Car “REVA”. Within Mahindra, the solar business is fully operational and there is a strong focus on other Cleantech areas including renewables, water and energy efficiency. Mahindra is developing several solar PV projects and also offering turnkey EPC Services to other solar developers.

EQ : What are the strengths of Mahindra Solar?

VP : Mahindra Solar emerged amongst the lowest bidders in the Batch 1 – Phase 1 of JNNSM and signed a PPA for 5 MW Solar PV Power Plant in Rajasthan. Our project development company Mahindra Solar One, which is a JV between Mahindra and Kiran Energy, is currently executing the project. For this project, we are deploying c-Si solar panels and trackers. Mahindra 56

EQ INTERNATIONAL November/December 11

was the first in the country to secure nonrecourse rupee debt finance from an Indian financial institution. There is also a growing interest from foreign banks for financing its solar projects.

EQ : What are the projects in Pipeline and the roadmap for the future?

VP : Along with the 5 MW grid connected PV project under JNNSM, we have several MWs of Solar EPC in the pipeline. We see a great opportunity in the Off-Grid space where several rooftop projects are under execution. Also there is a great potential to deploy solar hybrid telecom towers.

Mahindra solar one an its jv partner kiran energy has emerged has bagged three project of 20mw each in the batch two of phace one of jnnsm at a bid price of rs. 9.34 per kwhi.

EQ : Please highlight the EPC Expertise, Team Strength, Financing Advantage?

VP : Mahindra has developed a diverse team with strong expertise in project finance, procurement and project management along with advanced engineering and design capabilities in power plants and solar. The Solar industry is very dynamic with changing

landscape and it’s difficult to look beyond 6 months when it comes to technology. All the technologies have their merits and demerits.

The key is to raise finance and therefore we need to choose a technology that is bankable with a proven track record. When it comes to our EPC activities, we give choice to the developers to choose between leading c-Si and thin film technologies.

EQ : What is the view on Indian Policy & Regulatory framework and suggestions for a better tomorrow?

The Indian Solar Policy is very favorable and has many innovative things. The concept of bundling the solar power with coal power is really innovative as the burden of the high cost is not passed on to the consumer. In addition, the process of price discovery for arriving at solar tariff is optimized. The newly introduced Solar Renewable Purchase Obligation (RPO) and REC mechanism would enhance further growth in the sector.

The rationale behind the domestic content policy can be understood for developing the Indian Industry and Energy Security for the country. What’s important for the Government is to stay with the policy where Consistency and Continuity is the key. nnn

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SO L A R ENERGY

ACME 15 MW Solar Photovoltaic Plant at Khambat, Gujarat – A Case Study ACME

ACME Group shares Government of India’s vision of reducing the country’s carbon footprint and making it green. In line with this, ACME has set up 15 MW project based on solar photovoltaic technology at Wadgam, Khambat, Gujarat and a 10MW Solar Thermal Plant on tower technology at Bikaner, Rajasthan. For the 15 MW PV project the company installed First Solar, Inc. (NASDAQ: FSLR), thin film Cd-Te modules.

F

irst Solar manufactures thin film PV modules using an advanced semiconductor technology that offers enhanced suitability for affordable and efficient PV modules. Systems using First Solar modules generate electricity with no water, air emissions, or waste stream and have the fastest energy payback time and the smallest carbon footprint of any PV technology on a life cycle basis. The project execution was done by in house EPC team and the project was completed in less than six months from the date of commencement.

With the installation of these plants ACME is committed to significantly reduce solar electricity costs by sustainably using advance technology.

Project Development Approach The project was executed by in-house EPC team utilizing various strengths available viz. PV Engineering, Project Management, Civil construction and Electrical cum switchyard engineering.

ACME land team identified the land based on data of GHI and then set out to 58

EQ INTERNATIONAL November/December 11

15 MW project within a short span of time.

1. Finance - Financial closure was not easy as financial institutions have limited exposure to newer technologies in India and there is absence of any

acquire the land in earmarked areas. Land clearances were completed well in time to ensure smooth execution of the project.

The Complete Engineering, Layout, Output calculations etc. were carried out by In-house Engineering team. Seamless coordination with vendors of various materials helped project team exemplify execution excellence and ensured the project was completed within a record time of six months.

Challenges There were hurdles during the installation of the project, however, ACME overcame them and successfully installed

historical data pertaining to performance the PV plants in Indian context. Most of the financing in the present day is expected to be on recourse basis (Balance Sheet) 2. Weather management - Uncertainty of weather during monsoons caused delay in installation of PV panels. There were unexpected rainfalls during the month of August and September due to which work slowed down tremendously 3. Land acquisition – Land acquisition post PPA is a major challenge. Acquiring private land to ensure a contiguous piece of land for the project of this size in accordance with the land regulations in Gujarat, documentation, obtaining CLU/ NA certificate posed a grave challenge

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and impacted the projected cost of the plant 4. Project execution - Project execution in such a short duration also posed a challenge especially with regard to availability of skilled, semi-skilled manpower

EPC Projects in India

5. Transmission line - Project is ready for commissioning only the transmission line is awaited. It is expected to be commissioned towards the end of December

Learning & Way Forward l

Project cost and timelines need to be closely monitored

l

Availability of transmission line for evacuation is a prerequisite for project commencement

l

After analyzing the performance of already commissioned plants more stringent performance guarantees may be put in place by financial institutions/ developers

l

Bankability may continue to be a concern

Technology The plant operates on solar PV Thin-film technology. The advantages of using this technology over other PV technologies (such as Crystalline silicon technology, Flexible cells Technology, Concentrated photovoltaic etc) is that it outperforms crystalline silicon solar modules with the same power ratings in real-world environments for (a) low temp co-efficient (works better in high temp conditions) (b) better response to low light conditions (high light absorption in sun rise and sun set conditions). It also lasts longer than other systems and is more reliable and requires less maintenance. It is constructed for durability, easy installation, recyclability and is capable of providing power for a wide range of applications, including lighting, pumping water and telecommunications.

However, the high initial cost of the equipment involved does not quite motivate large-scale commercialization. Government of India, therefore, has launched several schemes for the phased commercialization of PV technology, and in 1993 - 1994 it entrusted IREDA with the commercialization of solar PV technology in India. PV Modules can be recycled; hence, the materials used in the production process can be used again.

Recycling is not only beneficial for the environment but also helps reduce energy needed to produce those materials thereby reducing the cost of fabrication.

Funding Agencies SBI and US Exim are the funding agencies backing this ambitious project. nnn

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Projects Executed / Under Execution: 2 MW - Chattisgarh 1 MW - Bonai 1 MW - Bambra 2 MW - Roorkee 5 MW - Rajasthan 5 MW - Gujarat 25 MW - Rajasthan

TOBACCO HOUSE 1, Old Court House Corner Kolkata - 700001 (India) Phone : +91 33 2230 7299 (4 Lines) Fax : +91 33 2248 4881 / 2479 3526 E-mail: s.ganguly@vikramsolar.com November/December 11 59Â WebsiteEQ:INTERNATIONAL www.vikramsolar.com

SO L A R ENERGY

Optimum Efficiency And Flexible Use

High Frequency Transformer With Transformer Switchover Jurgen Wolfahrt, Fronius International GmbH

O

ne of the many requirements of the modern inverter is a broad, coordinated input and MPP voltage range with a consistently high degree of efficiency across the entire operating range of the inverter.

To satisfy this requirement, Fronius is implementing a high frequency transformer (HF transformer) in most of its current inverters. This HF transformer has a transformer switchover that ensures a consistently high degree of efficiency right across the input voltage range.

It is often incorrectly assumed that the maximum degree of efficiency at a particular voltage is one of the factors responsible for producing a good annual yield, when it is in fact the more or less constant degree of efficiency over the entire MPP voltage range.

Thanks to the HF transformer switchover feature, the Fronius IG Plus and the Fronius CL offer maximum efficiency for almost any permissible string length.

The applied DC voltage is converted to a 50 Hz AC voltage via a full bridge (S1...

Disadvantages l

Low degree of efficiency resulting from

50 Hz technology

S4). This is then transmitted via a 50 Hz transformer and subsequently fed into the public grid.

Benefits: l

High degree of reliability due to fewer components.

l

Safety through galvanic isolation of the DC and AC sides.

high transformer losses. l

Heavy weight and volume (e.g. due to 50 Hz transformer).

Transformerless inverter technology The existing DC voltage is converted to a square 50 Hz AC voltage via a full bridge (S1...S4), then smoothed to a sinusoidal 50 Hz AC voltage via the chokes (L1+L2) and fed into the public grid.

Basic inverter concept There are basically three different inverter technologies: l

an inverter with a 50 Hz transformer.

l

an inverter without a transformer.

l

an inverter with a high frequency (HF) transformer.

50 Hz technology 60Â

EQ INTERNATIONAL November/December 11

Transformerless inverter technology

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Benefits: l

l

Compact and light due to lack of transformer.

Very high degree of efficiency (e.g. no transformer losses).

Disadvantages: l

Additional safety measures (residual current circuit breaker) required. In some countries, a lack of galvanic isolation between the DC and AC sides is not permitted.

l

Complicated lightning protection.

l

Not compatible with modules that must be earthed (e.g. some thin film technologies or rear-contacted cells).

HF technology

S8) then generates a 50 Hz AC voltage, which is smoothed to a sinusoidal 50 Hz AC voltage via the chokes (L2+L3) before being fed into the public grid.

Benefits: l

Compact and light, as the HF transformer is very small and light.

l

High degree of efficiency through reduction of transformer losses.

l

Safety through galvanic isolation between the DC and AC sides.

l

Suitable for all module technologies, as module earthing (positive and negative) is possible.

Disadvantages: l

Complex, technically complicated.

HF technology

l

More components and thus a higher likelihood of failure.

Transformer switchover Depending on the input voltage, the various technologies produce the following efficiency curves: When using an inverter with a 50 Hz transformer, there is always a fixed transformer transmission ratio between the primary and secondary side (DC and AC).

The higher the input voltage, the lower the efficiency.

This is connected, among other things, to the utilisation rate of the transformer, which drops at high voltages, causing the losses to increase.

In the case of transformerless inverters, the solar generator voltage must be greater than the amplitude of the mains voltage, which means that efficiency, taking into account tolerances, is at its optimum at an input voltage of approx. 350 V. This results from the mains voltage at 230 V, where the peak voltage is 325 V and additional semiconductor losses amount to approx.

This technology combines the advantages of the previous technologies.

The full bridge (S1...S4) generates a high-frequency square-wave signal with 20 â&#x20AC;&#x201C; 24 kHz, which is transmitted via the HF transformer (Tr1). The bridge rectifiers (D1...

D4) convert the square-wave signal back to DC voltage and store it in the intermediate circuit (L1+C2). A second full bridge (S5...

Transformer switchover

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EQ INTERNATIONAL November/December 11

61Â

10 V. Outside this voltage range a voltage step-up or step-down converter is active that increases or decreases the input voltage to the required value and reduces efficiency.

The HF transformer concept with a fixed transformer transmission ratio reduces efficiency even at higher input voltages.

However, by changing the transformer transmission ratio (transformer switchover), several efficiency peaks can be achieved through optimised transformer utilisation, thus ensuring a consistently high degree of efficiency right across the input range.

Transformer switchover basics In practice, it is rarely possible when designing the system to select the best input voltage range for the inverter, i.e. the range with the best conversion efficiency according to the datasheet. For optimum yields with any permissible connection, it is therefore essential that the efficiency is consistently high across the entire operating range.

Mode of operation

degree of efficiency over the entire voltage curve is consistently high.

For each switching operation between two windings, the power is briefly switched to zero before the next winding is connected and the power switched on again. This practically eliminates all switching losses.

Advantages of transformer switchover The transformer switchover results in a consistently high degree of efficiency across the entire input voltage range. It is not the maximum degree of efficiency at a particular voltage but the consistently high degree of efficiency right across the MPP voltage range that is partly responsible for a good annual yield. Thanks to the HF transformer switchover, the Fronius IG Plus and the Fronius CL offer maximum efficiency for almost any permissible string length.

At the planning stage there is therefore no need to consider whether the system is designed for high or low voltages. The voltage

variation due to different temperature conditions during normal operation is also compensated for by the transformer switchover.

Disadvantages of transformer switchover Due to the relay switching time, a short pause (200 ms) is necessary when switching to the next transformer winding.

During this short period, the input voltage increases towards the open circuit voltage, meaning that the secondary components must temporarily be able to withstand a higher voltage.

Transformer switchover details Each power module of the Fronius IG Plus and Fronius CL inverter range is fitted with an HF transformer, which has various active transmission ratios depending on the input voltage. There are three different areas with three different voltage ratios, so Fronius inverters with HF transformers also exhibit three efficiency peaks.

This enables a consistently high degree of efficiency to be achieved across the entire input voltage range. This is important at the planning stage and also when the temperature changes during system operation, as the voltage of the module varies according to temperature.

Thin film module example Due to the special design of the thin film module, these generally have lower currents and higher module voltages than crystalline modules. To enable reasonable string lengths and module combinations in

Fig.1

The HF transformer has three windings (V1, V2 and V3) on the primary side. Another winding is used for transmission in accordance with the input voltage, and this changes the transmission ratio.

E.g.: 230 - 280 V = U1, 280 â&#x20AC;&#x201C; 370 V = U2, 370 - 500V = U3 To guarantee the best possible transmission, the switching limits change with the output voltage (e.g. for USA mains).

Fig.1

This ensures that there is always a constant voltage (U) on the secondary side, transmission losses are minimised and the 62Â

EQ INTERNATIONAL November/December 11

Fig.2

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combination with the smaller fill factor, the inverter needs a broad and coordinated input and MPP voltage range with a consistently high conversion efficiency across the entire operating range.

Due to the described module properties, there are very few different string lengths within the operating range of the inverter compared with crystalline modules.

The following figure illustrates that three different string lengths are possible in the case of a thin film module with open-circuit/MPP voltages of 95 V and 65 V respectively and a Fronius IG Plus with an operating range of 230 V to 500 V. The temperature coefficients of the modules and the temperature range in question of -10°C to +60°C result in the following MPP ranges according to string length: Fig.2 It is apparent that a configuration covering the entire MPP voltage range and all different string lengths is feasible due to the consistently high conversion efficiency.

Comparing this to the other inverter concepts demonstrates that it is usually only possible to have one string length at optimum efficiency, while other string lengths lead to significant declines in efficiency and hence reduced yields.

Fig.4

An inverter without a transformer achieves its optimum efficiency at one particular DC voltage. At all DC voltages above or below this level, it requires a stepdown or step-up converter, which also results in efficiency losses Fig.4 The ideal string length lies in the middle

transformer switchover takes place on the input voltage side.

They are thus well able to cater for the requirements of thin film modules, as well as crystalline ones, and can therefore be used with all module types. nnn

MPP voltage range (blue range). Using the lower or upper MPP voltage ranges leads to reduced yields.

Fig.3

In the case of an inverter with a transformer but no switchover, as shown in the following figure, the efficiency figure falls across the entire MPP voltage range of the inverter as the DC voltage increases. Fig.3 Only in the lower MPP voltage range (red range) is the highest maximum efficiency achieved.

Summary In addition to the above mentioned advantages of galvanic isolation and lower transformer losses, Fronius inverters that employ HF transformer technology exhibit a consistently high degree of efficiency right across the input voltage range, as the

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SO L A R ENERGY

Thomas Wittek

Nitin Bhosale

Conventional Central Inverter V/s REFUsol 333K Thomas Wittek & Nitin Bhosale - Refu Solar Electronics Pvt.Ltd.

Central inverters are the a most popular choice of PV system installers for large and medium size PV power plants. Grid inverters are continuously undergoing reform due to technological development, competitiveness and changing market preferences in different regulatory environments. This article highlights the salient features of ‘REFUsol 333K - a new generation central inverter’ which helps reduce the balance of system cost of the entire project; it also discusses the other benefits of using REFUsol 333K over the conventional central inverters delivered as a technology advantage.

Need of innovation Most of the inverter manufactures have developed a range of highly competitive and cutting edge technology products in their product portfolio. Conventionally, key focus of development was: • •

•

•

To develop transformer less and compact inverters To improve efficiency of the product using high efficiency fast switching devices and Developing suitable capacity units and providing effective cooling system to the inverter units Developing compact devices along with fast and precise MPP tracking, integrated data logger, monitoring facilities etc.

Apart from the above considerations, REFUsol 333K has been developed after careful understanding of entire PV application and prevailing PV plant development trends worldwide. Clear understanding of 64

EQ INTERNATIONAL November/December 11

specific requirements of the product during different project development phases has helped designing the product with improved reliability for overall PV plant operation.

REFUsol 333K offers several benefits to the customer throughout the PV plant project life cycle. The use of REFUsol 333K in the project changes the entire project economics; it mainly saves the cost by reducing Balance of System (BoS) requirement of the plant.

Other design features implemented while developing the REFUsol 333K those are mainly responsible for cost reduction and improved reliability are discussed below;

on selected PV and inverter technology together. The major factors responsible for the changes in project configuration and hence BoS are: •

System voltage and rating of the selected PV modules and inverters

•

No load voltage of the PV modules

•

Range of maximum power point voltage window of the inverters

•

Minimum and maximum ambient temperature at the PV plant location DC side configuration is very important

with the view to optimize the plant configuration in terms of most efficient and

a) Reduced BoS components

cost effective design. Generator combiner boxes, mounting structure frame design and

A reduction of system costs was in the main focus since the beginning of developing the innovative REFUsol 333K concept; however it inherently facilitates the PV designer to build the entire PV system with higher conversion efficiency. The Balance of system required for a PV power plant depends

DC cabling design depending indirectly on the selected inverter. Design attributes of the inverter should offer maximum flexibility to optimize the plant configuration to reduce overall costs although it is very difficult to compare actual cost benefits of any particular attribute implemented.

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• Combiner Boxes Quantity of combiner boxes required for any PV plant mainly depends on the PV array design for the selected PV modules and inverter for the ambient condition where the plant is located. Specific to the inverter it all depends on maximum number of modules that can be connected in a string, more the number modules per string lesser the combiner boxes will be required (assuming rest of the parameters and project component remains same). Maximum open circuit voltage (Voc) and maximum power point voltage (Vmp) of the modules at minimum temperature are critical and should fit in the inverter specifications strictly. Minimum 20 percent of the combiner boxes can be reduced

•

•

•

The high output voltage of 690 volts decreases the overall system losses to 58 percent compared with a 400 volt system.

The higher output voltage also leads to a reduction of transmission losses by 76 percent for the same cross section.

The losses in the cables between the Inverter and medium-voltage transformer can be reduced by one third.

Compact size REFUsol 333K can be installed outdoor in the PV array field strategically to reduce the DC cable overall lengths.

REFUsol 333K central inverter is designed with the view to do decrease specific drawbacks encountered in the inst allation and performance of conventional central inverters Unlike conventional central inverters, REFUsol 333K is a transformer less inverter and multiple devices can be connected to a transformer to operate in parallel, which allows cheaper installation with reduced losses.

IP65 protected electronic unit REFUsol 333K is a compact unit which can be installed outdoor and hence the cost associated to building control rooms required for the inverters can be saved.

by use of 333K inverter if compared with the plant of similar capacity designed with conventional central inverters.

• AC and DC cable Higher AC and DC voltages of REFUsol 333K have the advantage that the line losses can be reduced almost everywhere in the system. Firstly, in the inverter, which forms the part of efficiency gain, secondly the cable losses in the PV installation will be significantly lowered. In addition, the installation costs for cabling and the associated costs are reduced by designing the plant with REFUsol 333K.

If compared to a system designed with conventional central inverters, the system designed with REFUsol 333K inverter would save typically around five percent of Balance of System (BoS) cost. However, saving of two percent can be estimated in overall capital cost of the installation.

b) Other benefits to the customer Besides saving on BoS component cost REFUsol 333K unique feature which offers better utility to the costumer are highlighted

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below.

•

Suitable for outdoor areas and industrial applications

•

Lower Cost with higher efficiency

•

Lower weight approximately 850 kg – hence logistic and infrastructure cost will be reduced considerably

•

No special qualification is required for installation of the inverters

•

Higher system voltage design enables 690VAC enables the parallel operations of several devices on just one transformer what results in lower system losses and lower balance of system cost

•

Higher output voltage leads to a reduction of the conveyance losses of 76% compared with 400VAC with same cable cross section.

•

Input voltage of up to 1500V it is possible.

•

No auxiliary power supply is required.

•

It DC-DC booster allows to start power in feed to the grid at 600W hence contributes to generate additional units for the plant when the sun is low.

•

Effectiveness of whole system will increase due to lower losses in the string, reduced cable length and optimized plant layout.

•

Robust and low m ainten ance ‘temperature controlled air cooling’ system allows the operation under extreme climatic conditions.

•

Integrated data logger to record and forward relevant data to analysis and control.

•

REFUsol ULTRAEta®Pluscircuit topology •

Very high peak efficiency of 98.5%

•

Wide DC Voltage range

•

Especially high efficiency at low DC voltage link

•

Fixed N-Potential (low EMC disturbances, low leakage current)

Use of REFUsol 333K improves the overall profitability of the solar PV plant as by minimizing electrical losses in the system, reducing BoS components and improving the performance ratio of the plant. nnn EQ INTERNATIONAL November/December 11

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SO L A R ENERGY

REFUconnect – A Wireless Networking Device

Mukund Shendge

Nitin Bhosale

Mukund Shendge & Nitin Bhosale- Refu Solar Electronics Pvt. Ltd.

Designing performance monitoring and control system for PV power plant often faces challenges at the installation phase. Communication of the inverter data loggers with remote server becomes more complex for PV system installed on distributed roof-tops or large ground mounted PV systems; especially when there are many slave devices required to be monitored form remote location.

REFUconnect is a new wireless networking device which is introduced with the view to provide simple hassle free networking of large and distributed PV systems.

Need of innovation Conventional access techniques using serial bus interface solution which has certain limitations such as: •

Signal transmission is limited by the distance between the devices

•

Limited number slave nodes can be added (maximum 31 inverters can be used if USS protocol with RS485 hardware used).

Similarly, reliable connection and data transfer in case of high interference industrial environment and distributed PV systems would be difficult with the conventional access techniques. To avoid difficulties in such scenarios new wireless module REFUconnect is developed.

REFUconnect for easy networking The new wireless networking via REFUconnect simplifies the planning and installation of the communications connections of all inverters in a PV system.

The REFUconnect radio module is based on a radio standard which also ensures secure and reliable connections in high interference industrial environments.

It is possible to connect up to 2000 inverters to this system. In this context, the REFUconnect is simultaneously used as a repeater, so that distances over several kilometers can be bridged without difficulty.

The range of such an individual connection can total up to 500 m. The radio modules only require a very low power level 66

EQ INTERNATIONAL November/December 11

and are supplied directly by the inverter, which means an external power supply, is not required. REFUconnect establishes redundant connections automatically in the network and therefore ensures an errorfree and stable transfer of the inverter data. The network is password-protected, so that the data are transferred securely and that they remain invisible to other external participants. Effectiveness of REFUconnect in networking can be evaluated from following scenarios: a) Distributed roof-top PV installation – (Typical distributed roof-top installation with grid inverters located at larger distance from each other). Networking of such devices using serial bus interface technique will be much more complex, time consuming, and costlier. However, the use of REFUconnect will provide easy, hassle free and reliable communication. b) Large ground mounted PV systems – Larger capacity grid PV power plants demands higher flexibility in terms of positioning of inverters at strategic locations, also the number of inverters required to be monitored are much more than small roof-top systems. REFUconnect allows installer the flexibility of networking up 2000 inverters in the system. Inverters can be placed at strategic locations to reduce cost of cabling at suitable distances. In case the distance between slave devices (inverters) exceeds more than 500m; an additional REFUconnect (repeater) can be placed within the intermediate distance to keep the radio signal connectivity intact with the master (REFUconnect device). Mapping

down the required number of repeaters, installers can easily bridge the distances over several kilometers. c) PV systems in high interference industrial environments – Wired networking communication technique often requires shielding to the cable. The possibilities of electromagnetic interference created due to wired communication can be effectively avoided with use of REFUconnect wireless device. REFUconnect based on radio standards and ensures secure and reliable connections in high interference industrial environment.

Key highlights REFUconnect wireless networking simplifies communication between all the inverters within a photovoltaic system. The REFUconnect module is based on a radio standard which ensures secure and reliable connections in high interference industrial environments. It is possible to connect up to 2000 inverters to this system. All inverter data is transmitted smoothly and reliably; the network is password-protected for maximum security. nnn

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The right Solution for Renewable Power Systems: highest standards for maximum efficiency.

As one of the worldâ&#x20AC;&#x2122;s leading players in clean energy today, with utility-scale installations currently placed around the world, Bonfiglioli has the innovative know-how and technical capacity to bring utility and large-scale PV power plants to life.

Visit us at Booth #1116 at Inter Solar India

We design and manufacture a wide range of high-efficiency products for energy conversion from 30 KW to 1.6 MW inside the Bonfiglioli Vectron Center in Germany , the heart of innovation in the development of power conversion systems that yield a great efficiency and an optimal return of investment.

With over 12 years experience in the Indian market, 15 branches spread across the country for sales and after-sales service and a warranty coverage for the lifetime of the power plant up to 20 years, Bonfiglioli is one of the leaders driving the green revolution in India.

Bonfiglioli Transmissions Pvt. Ltd. Survey No. 528, Perambakkem High Road, Mannur Village, Sriperumpudur taluk, Tamil Nadu - 602 105, India Ph: 044-67103800 - Fax: 91-44-67103999 pv.india@bonfiglioli.com - www.bonfiglioli.com

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SO L A R ENERGY

Smart Solar Power Inverter Reference Design Manish Sharma- Applications Engineer, India Solution Center & Applications Center, Microcontroller Solutions Group, Freescale Semiconductors India Pvt LTD,

Solar Fundamentals Photons in sunlight hit the solar panel and are absorbed by semiconductor material – silicon. Electrons (negatively charged) are

resistor represents the leakage currents (very small). Series resistance represents the wiring losses.

In the technical parameters of the solar cell panel are defined: VMP – voltage at MPP IMP – current at MPP The Inverter for the solar cell panel must achieve the operation on the MPP. This method is called MPPT – maximum power point tracking. The presented inverter has implemented the P&O (perturb & observe) algorithm for MPPT. To get maximum power from a photo voltaic (PV) panel require operating at the optimum voltage.

knocked loose from their atoms, allowing them to flow through the material to produce electricity. Due to special composition of solar cell, the electrons are only allowed to move in a single direction. An array of the solar cells converts solar energy into a usable amount of direct current (DC) electricity.

A solar cell may be modeled by a current source in parallel with a diode, shunt and series resistances. IL represents the max current of the solar panel (short current).

Diode forms the I-V characteristic. Shunt 68

EQ INTERNATIONAL November/December 11

Maximum Power Point Tracking (MPPT) Concept.

Reference Design specification The system is designed to convert the

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low voltage DC power from the solar panel to the power line level AC voltage 230 V 50 Hz. The application meets the following performance specifications:

A st andard inverter topology is chosen to meet the basic specification.

The system incorporates the following blocks:

• Control of the PWM push-pull DC to DC converter • Control of the PWM full-bridge DC to AC inverter through the digital isolator • Control of the PWM two phase SEPIC converter for the battery charger (as option) • Direct input voltage and current sensing by integrated on-chip analog to digital converter (ADC) •

Direct battery voltage sensing by the integrated on-chip ADC

• Direct DC-bus voltage sensing through the isolated analog amplifier and on-chip ADC • Direct output AC voltage and AC current sensing through the isolated analog amplifiers and ADC. • Maximum power point tracking technique (MPPT) P&O method used • Pure sine voltage generation by the PWM control • Input under-voltage protection implemented in software • Output high and low voltage limits implemented in software • Output over-current protection implemented in both - hardware and software

• high voltage output side. The main control unit–digital signal controller (DSC) is placed on the primary side to start to run when the solar panel starts to source minimum output power. The power conversion from the DC low voltage to the high voltage DC bus is maintained by the standard push-pull type converter and isolation power transformer.

The conversion from the high voltage DC bus to the standard AC power line voltage is maintained by the inverter in the full-bridge configuration. The standard AC output filter is placed at the output to meet the output voltage regulations.

The main design parameters are chosen to reach a wide range of usability: The inverter can be powered by one solar panel with the 36 V DC nominal output voltages or by two solar panels connected in series each with the 18 V DC nominal output voltages.

• The inverter can also be powered by the three pieces of the lead-acid accumulators connected in series. The battery charger can be implemented as the software (SW) option.

• Isolated RS-485 communication line on board

• The maximum output power depends on the solar panel properties and can reach up to 400 VA.

Reference Design Description

• The output voltage is 230 V / 50 Hz + 10 %.

This reference design is a DC to AC inverter for the solar panel. This design example shows how to convert the small DC voltage with highly variable power from the solar panel to the AC output voltage 230 V / 50 Hz sine shape. The output power is sufficient to source small AC powered appliances or lights in the destinations without a power grid. The aim of this design is to present the maximum power point tracking (MPPT) feature. Using the Freescale MC56F8023 device ensures cost-effective implementation for this type of inverter application.

The overall structure of this inverter can be split into two sections, the primary low voltage input side and the isolated secondary

• Pure sine output voltage with a maximum of 3% harmonic distortion.

• The input under-voltage and output overcurrent protections implemented • Hardware for the isolated RS485 communication line built. The communication protocol can be implemented in accordance to the final requirements..

• Efficiency better than 80 %.

• MPPT implemented, and the P&O method used.

Reference Design Block Diagram Description

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Solar panel

• DC to DC Converter with MPPT implemented • DC to AC inverter • Output filter • Control unit with DSC MC56F8023 • Battery charger The MC56F8023 executes the control algorithm. In response to the input power from the solar panel and feedback signals, it generates PWM signals for the push-pull DC to DC converter on the low voltage side and the PWM signals for the AC pure sine voltage generation on the isolated secondary side. High-voltage waveform generated by the DC to AC inverter goes through the output filter to the output connector. The hardware circuitry is designed for the Off-Grid mode and for On-Grid mode. The hardware for the battery charger is also on the main board.

This inverter includes the maximum power point tracking (MPPT) feature to achieve the maximum efficiency of the energy harvesting.

The software for the battery charger is not yet implemented.

Reference Design MPPT description The DC output power sourced from the solar panel is periodically computed. The P&O algorithm for the MPPT is applied as per the below graph. This method is based on the simple and effective P&O algorithm.

The power point P1, we can try to sink higher power from the solar panel by increasing the current from the panel. This implies a new power point P2. The actual new power is calculated as the input voltage multiplied by the input current. This value is compared with the previous sampled value. If the new power value is higher than the previous value, the input power grows. Thus, the moving direction of the power curve is correct. In the next step we can try to sink still higher current from the panel. The power measurement in the new point can be P3 in comparison with the previous value. The next step is analogical—this is the case in which the output power from the solar panel is lower (Pn)—go back and try to find the point, EQ INTERNATIONAL November/December 11

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inverter will be controlled

by DSC MC56F8025.

Reference Design Block Summary

where the sourced power from the panel is highest. Arrows in below graph shows the moving direction of the new power point.

The incremental step depends on the power change in the previous step. If the power change is higher, the next step is higher.

If the power change is smaller, the step to the next power point is also smaller. The power curve on the top (in the Pmax point) is horizontally flat. This means, that the power change is small and the step change is also small. Thus the maximum power point catch is very accurate. The frequency of checking the power delivered by the solar panel must be sufficiently high to properly track the MPP when the illumination conditions are quickly changed. The system was tested by the intensive deeply changing weather (illuminating) conditions the MPP tracking was quick and accurate.

Reference Design Functional block description: The actual solution is based on the DC/DC up-converter followed by the fullbridge MOSFET state. The control software maintains also the MPPT function. In the first phase the inverter is controlled by the DSC MC56F8023. The whole design comprises the battery charger for storing the energy from the solar panel. This option can improve the MPP tracking for solar panel and allows the off-grid working mode of the inverter. The battery use functionality will be implemented in the second phase and the

The detailed descriptions of different block of the MC56F8023 solar inverter reference design are as follows: System Connection with Solar Panel

can be used when the board is used outside any main board. When the DSC board is inserted into a main board, this power supply is not used.

Auxiliary power supplies This block is comprised of a 12 V DC power supply assembled from an LM5010A, a 3.3 V DC power supply assembled from a FAN8303, and a 5 V DC power supply for the analogue circuitry assembled from an LM317. This block provides the power for all the control and measurement circuits.

Power transformer These transformer blocks are two power MOSFETs, placed on the heat sink, on the top and bottom sides of this box. These are push-pull MOSFETs on the primary side of the DC to DC converter. There are three big electrolytic capacitors together with two MP capacitors. They serve as the energy storage for the power DC/DC converter.

High voltage DC-bus This part of the inverter is comprised of the bridge rectifier, the associated inductor, and the main DC-Bus capacitor of 330 μF/450 V.

Full-bridge inverter This block consists of four power MOSFETs, four free-wheel diodes, and the associated capacitor for each half-bridge.

The half-bridge drivers for this inverter are placed on the bottom side of the PCB.

Input and output The input located on the left side of the board provides connections to the two solar panels and to one lead-acid back-up battery.

On the right side of the inverter is the output connection, it provides the generated sine output voltage of 230 V AC for the load.

DSC controller board This daughter card is assembled from an MC56F8023 digital signal controller and it controls the whole inverter. On the board there is a dedicated small power supply that

Output filter The output filter is the main reconstruction filter– it filters the PWM switching frequency and puts through the generated 50 Hz frequency. In the bottom half of this box is the standard EMI filter.

Battery charger This block is the L and C power components with power MOSFETs and diodes mounted on the heat sink.

Analogue measurement circuits The analogue measurement circuit consists of operational amplifiers with associated components for the input voltage and current measurements. The other analogue circuits are placed on the bottom side of the PCB.

Communication interface Communication block is an isolated RS485 interface. This provides connection to the higher supervisor system.

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MiniSKiiP

®

3-level

Highest current density: 4.9 A/cm2 Current / footprint in A/cm²

4.2 A / cm2 3.0 A / cm2 Modules with screw connection

Modules with press pin connection

4.9 A / cm2 MiniSKiiP® spring contacts

Highest current density with 4.9 A/cm2 75 A – 200 A @ 650 V blocking voltage For compact solar inverter and UPS up to 85 kVA 15 million MiniSKiiP ® modules in application Saving production costs with one screw mounting

Compact inverter design No space-consuming bus bar connections Spring contacts allow easy PCP routing No Pin-Through-Hole element

Australia +61 3-85 61 56 00 Brasil +55 11-41 86 95 00 Cesko +420 37 80 51 400 China +852 34 26 33 66 Deutschland +49 911-65 59-0 España +34 9 36 33 58 90 France +33 1-30 86 80 00 India +91 222 76 28 600 Italia +39 06-9 11 42 41 Japan +81 68 95 13 96 Korea +82 32-3 46 28 30 Mexico +52 55-53 00 EQ 11 51 Nederland +31 55-5 29 52 95 Österreich +43 65 80 INTERNATIONAL November/December 111-58 6371 Polska +48 22-6 15 79 84 Russia +7 38 33 55 58 69 Schweiz +41 44-9 14 13 33 Slovensko +421 3 37 97 03 05 Suid-Afrika +27 12-3 45 60 60 Suomi +358 9-7 74 38 80 Sverige +46 8-59 4768 50 Türkiye +90 21 6-688 32 88 United Kingdom +44 19 92-58 46 77 USA +1 603-8 83 81 02 sales.skd@semikron.com www.semikron.com

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SO L A R ENERGY

Extreme Conditions for PV in India are the Ultimate Test for Inverters Rakesh Khanna, General Manager, SMA India

Heat records, desert storms and tropical rainfall – PV power plants in India are exposed to particular weather conditions which the inverters must also be able to withstand. Therefore, SMA regularly subjects the inverters of the Sunny Central family to special stress tests demonstrating impressively that they are capable of producing maximum performance even under extreme climatic conditions.

Sunnycentral After Dust

R

akesh Khanna, General Manger of SMA India, is fully aware of the frequently difficult ambient conditions prevailing in his country, but he also realizes that the subcontinent with its rapidly growing economy has great opportunities to gain by expanding photovoltaic. “Temperatures of around 50 degrees Celsius, sandstorms and monsoon rains are no exception in our country”, explains Rakesh Khanna.

“On the other hand, we have over 300 days of sun per year, and in many regions yields of up to 1 600 kilowatt hours per kilowatt of plant power can be achieved. Thus, the energy requirement of millions of people can be met.” The quality of the deployed PV products is therefore of crucial importance.

“With the outdoor-compatible Sunny Central CP inverters, SMA is ideally positioned to cope with the climatically challenging regions of India”, says Rakesh Khanna. This 72

EQ INTERNATIONAL November/December 11

is borne out by the SMA stress tests which provide impressive proof of the high quality of the inverters.

1 000 Hours’ Record Heat In the SMA climate chamber encompassing a DC voltage range of 1 200 V in a test space volume of 48 square meters,

each inverter is subjected to a climate stress test prior to serial production launch. The inverters remain in the climate chamber for up to 1 000 hours. The test simulates extreme climatic conditions within a temperature range of –40 °C to +90 °C in conjunction with humidity of up to 95 percent. It yields precise values on power output, efficiency levels and the electrical endurance of the components used in the inverters.

SMA Design for High Altitudes

Dustblowing Turbine

PV power stations located at high altitudes also have to cope with extreme conditions. True, the reduced inverter cooling capacity resulting from the lower air pressure is compensated by the sinking temperatures at higher altitudes, but at the same time the dielectric strength of the air is also diminished. At heights over 2 000

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Climatechamber

m above sea level, a reduction in maximum voltage and output power must be allowed for. The dimensioning and maximum voltage of the Sunny Central CP devices are adjusted to compensate for this. All control voltage circuits of the Sunny Central inverters are designed for altitudes up to 4 000 m above sea level, and they are also operated with a modified DC window.

Resistant to Sandstorms The extremely fine dust and sand which penetrates the smallest cracks and openings during sandstorms can settle everywhere. This poses a threat to the operation and longevity of the entire PV plant. Particularly in desert locations with a maximum of guaranteed solar irradiation and thus with greatest potential for the future, this is a problem which could put yields at risk. For this reason, SMA has tested the desert-worthiness of the outdoor-compatible inverters of its Sunny Central CP series. At wind speeds of 1.5 m/s to 20 m/s, brick dust was blown horizontally straight at the inverter. With positive results - the OptiCool cooling system integrated in the Sunny Central CP prevented dust from settling in the interior of the inverter. Dust deposits were only found on the exterior of the device and on the seals.

No dust inside

Central CP family and the inverters of the Sunny Central HE series for indoor installation have demonstrated clearly in the stress tests that they meet highest quality demands and that they deliver maximum power even under extreme ambient conditions. At an ambient temperature of up to 25 °C, the maximum power supplied by the inverters of both series is even 10 percent higher. High-tech features such as comprehensive grid management and intelligent power management provide even more benefits for the PV power station operators.

the High Power Solutions sector for over 800 large-scale projects with more than 4 gigawatts of installed power. The German company can look back on 30 years of

More than 4 Gigawatts of Installed Sunny Central Power Worldwide

Maximum PV plant yields are guaranteed by the new, integrated string monitoring concept OptiProtect. By means of a central monitoring function with automatic error detection and elimination, plant failures are avoided when faults occur on the modules, thus preventing disconnection of the PV plant.

The results of the climate stress tests prove just how ideally suited the Sunny Central CP and HE inverters are for deployment in the booming Indian PV market. “As far as our products are concerned, we need solutions which can withstand the extreme ambient conditions of the subcontinent,” explains the General Manager of SMA India, “After all, the key to the continuing economic development of India lies in the expansion of solar energy.” In the fall of 2010, SMA opened a Sales and Service subsidiary in the Indian metropolis of Mumbai. From here, Rakesh Khanna and his colleagues take care of various PV power station projects, including several large-scale projects in the State of Gujarat. SMA India is also well set up for enabling electricity supply in remote, off-grid regions. Here, SMA offers mature solutions for backup and off-grid systems.

Both the outdoor devices of the Sunny

In 2010, SMA supplied inverters in

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Dustcovered Sunnycentral

experience in the solar sector and is global market leader for inverters today. Apart from the company headquarters in Niestetal, Germany, where some 4 600 employees plus a seasonally varying number of temporary employees are based, SMA has a workforce of approximately 800 employees around the globe and is represented in 19 countries on four continents. nnn EQ INTERNATIONAL November/December 11

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SO L A R ENERGY

Importance Of Fuse Development For The Solar Power Market.

Ben Rooke, Product Manager, Pv Fuses At Cooper Bussmann

I

n a relatively short time the small PV systems of only a few watts have developed first to a few kilowatts and more recently to as large as 10MW. During this time a number a number of key changes have occurred to the topography and dimensions of the basic components and indeed the types of components themselves, especially those whose primary function is overcurrent protection.

Looking to the future the trend is to extract greater efficiencies and power from PV installations through new materials and improved insolation technology ie.

PV concentrators. The corollary of that will be the requirement for better system overcurrent protection. Already the move globally is for the use of higher voltages of up to 1000Vdc and beyond, in some cases. This has put pressure on PV system OEMs to source and install protection solutions that are not only capable of meeting the protection requirements but can be easily packaged.

It is worth reminding ourselves that in faulted circuits PV modules may be damaged by reverse overcurrents exceeding the reverse current withstand of the modules IMOD_REVERSE. Typically the effects of fault currents may range from permanent damage to PV modules and reduced efficiency to broken conductors resulting in electric arcs and fire. Dangerous fault currents can originate from external sources, ie. from modules or strings of modules that are connected in parallel to the faulted string, from storage batteries in the system or 74Â

EQ INTERNATIONAL November/December 11

from backfeeding through grid-interactive inverters. However, correctly rated PV fuses are able to protect PV modules or strings and internal wiring against these dangerous reverse overcurrents.

As a manufacturer of fuses we are constantly receiving approaches from PV power supply manufacturers for solutions that meet these challenges. Typically they are looking for certainty and assurances in terms o f proven performance and

capability. Unlike typical grid connected AC systems, the available short circuit current on a typical PV system is limited and the overcurrent protective device needs to operate effectively on low levels of fault current. To this end we have conducted extensive research and development of devices that are specifically designed and tested to safely protect PV systems with high DC voltages and low fault currents.

The net result of this work is a range of PV fuse links that meet the necessary protection criteria across the system.

At string level, our 10 x 38mm fuse links that meet all the specific requirements demanded by system manufacturers, most notably protection up to 1000Vdc. The Solar PV range offers class leading performance, clearing faults as low as 1.35 x l (fuse rating) @ 1000Vdc and is suitable for industry standard dimensioned 4, 5 and 6 in crystalline solar cell based modules and thin film modules.

In addition these fuse links have been tested to withstand the typical cycling conditions specific to solar panel operation and the environmental impact associated with system location. In effect, this means that the fuse will perform to its optimum level for the duration of the system life.

The new range of XL Style, square body fuse links in voltage ratings up to 1500Vdc provide OEMs greater flexibility in the protection of higher power PV arrays. No other fuse manufacturer

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has achieved this landmark voltage rating in this package, representing a significant breakthrough in fuse design and performance.

The new series of NH1 square bodied photovoltaic fuse links has ratings up to 1000Vdc; these are among the smallest NH style fuse links to achieve this rating and are one of the most comprehensive ranges of NH size fuse link solutions on the market with amp ratings from 50A to 160A. The 14 x 65mm range of photovoltaic fuse links comprises 15 and 20A ratings at 1500Vdc and 25 and 32A ratings at 1300Vdc, making this the only series to offer these voltage and amp ratings in this package size.

Passion for power

Come over to the sunny side.

Electrical installation for photovoltaic plants made easy!

Also available is a range of IEC 60269-6 (gPV) 14 x 51mm photovoltaic fuse links. This new ferrule-bodied series comprises 15 and 20A ratings at 1100Vdc and 25 and 32A ratings at 1000Vdc, providing PV system OEMs with a compact protection solution for higher voltage distribution networks.

Packaging is also a key criteria for system OEMs. For example, with space limited in combiner boxes because of the desire to minimise the footprint and improve the overall aesthetic, the preferred dimensions for the fuse link is 10 x 38mm. This globally accepted package size is further enhanced by a choice of mounting options with standard ferrule, bolt and versatile PCB mounts on offer. The low power dissipation of the fuse also contributes to minimum energy loss and heat generation within the combiner box.

The other factor that provides certainty and comfort for OEMs is compliance with standards. However, here the situation is fluid to say the least. Industry expert Dr Herbert Bessei puts it succinctly: “Increasing demand for alternative energy and strong financial support by some governments has boosted the installation of PV power systems faster than commonly accepted rules and international standards could be developed. Many terms, definitions and test procedures are still undefined and used in different ways.”

Good preparation is the key to success: especially true when

The existing standard,IEC 60269-6, was published in September 2010 together with UL 2579 which gave the PV industry standards to work with.

installing photovoltaic plants. Hensel is now offering new PV

Updates to IEC 60269-6 are already being considered to better meet the requirements of the industry, installation codes such the NEC in the USA and IEC 60364* in Europe, together with installation guides for PV systems such as IEC 62548 “installation and safety requirements for photovoltaic (PV) generators”, are also due for publications shortly.

Hensel provides standardised, turn-key manufactured solutions

What is certain is that as PV systems evolve with new equipment, new wiring procedures and methods of installation, the development of the PV fuse will continue in tandem. As the asset value of PV energy systems increases, in terms of the revenue that can be generated, it would be wholly inappropriate and commercially suicidal not to protect that asset with a product that meets the necessary performance requirements and standards. Needless to say we at Bussmann are on the case! nnn

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generator junction boxes with string overload protection or blocking diodes with sustainable protection against damages . to meet all requirements and help the electrician in their profes sional execution of PV installations.

new

www.enysun.eu

Hensel Electric India Pvt. Ltd 35, Kunnam Village, Sunguvarchathram Walajabad Road, Gustav Hensel GmbH /&Flextronics Co. KG 4th km behind Samsung D-57368 Lennestadt Sriperumbudur 631 604.

Kanchipuram Dist., Tamil Nadu INDIA Ph: +91 044 3727 0202 Fax: +91 044 3727 0200 info@hensel-electric.in www.hensel.in

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Professional Photovoltaic Distributors

SO L A R ENERGY

Surge Protection For PV Systems Alexandre Welferinger, Christian Macanda - CITEL SAITEL

Probably most of our readers know what the role of a surge protection device (SPD) is. Nevertheless technical parameters, selection criteria and core technology aspects might be more obscure to many of us. In this intention we will review these following points in this short article, which we hope will be as easy to read as possible and will you help make your selection for surge protection easier.

• Important technical parameters of SPDs • Selection criteria for DC applications, • Technology selection.

1- Basic parameters knowledge To get started we define a few key parameters used for surge protection device.

These can be used invariably for AC or DC applications.

•

Type 1 or 2: this defines the capacity of the SPD to withstand different types of surges or spikes. Type 1 SPD is designed to withstand direct lightning impact (defined as 10/350µs impulse) whereas type 2 is designed to resist all types of secondary surges : induced lightning current (defined as 8/20µs), industrial surges, grid faults….

Although Type 1 SPD is “stronger” than Type 2 it should not be seen as better.

Both have different criteria for selection, installation and application.

Although IEC standards define a Type 1 and Type 2 SPDs, it is not uncommon to read about respectively class B and C surge protector : these names are false and not in line with standards anymore).

•

•

76

Maximum operating voltage (Uc): This is the maximum AC voltage that can be applied continuously to the SPD. In photovoltaic systems this parameter is now referred to as Ucpv.

Nominal discharge current (In): This is the 8/20µs impulse that the SPD EQ INTERNATIONAL November/December 11

can withstand without destruction 15 times.

•

•

Maximal discharge current (Imax): This is the 8/20µs impulse that the SPD can withstand without destruction 1 time only. Imax is by definition always superior to In. Impulse discharge current (Iimp): this is the 10/350µs impulse that the SPD can withstand one time in case of a direct lightning impact (and as such is only valid for Type 1 SPD).

Discharge currents are usually given per pole. By instance In=20kA for a CITEL DS50PV means 20kA between positive and ground and 20kA between negative and ground. IEC defines a parameter called Itotal as the total impulse current conducted by a multi-pole SPD : in the previous case this Itotal would then be 40kA. •

Protection level (Up): This is the voltage seen by the equipment protected by the SPD during the conduction of the nominal impulse current In. Often Residual voltages at discharge currents lower than In are mentioned.

There are of course numerous other technical parameters that make each model of SPDs different to another one, however the above mentioned parameters are the most currently used. These can be used invariably for AC or DC applications.

Now we will see how to use them using the PV generators most important parameters.

2- Selection criteria for DC application The advices below are given with respect to the following European standards, which are the most advanced standardization in PV field: •

UTE C15-712-1 = HD 60364-7-712 : guide for installation of grid-tied PV systems

•

UTE C61-740-51 = EN 50539-11 : SPD testing for DC application

•

UTE C61-740-52 = CLC/TS 50539-12 : Selection & installation of SPDs gridtied PV systems

For PV applications the prEN50539-11 SPD test standard focus on 4 main parameters to be used by the PV designers.

•

Ucpv : Maximum DC voltage on the surge protectors (V)

•

Iscwpv : Short-circuit withstand (A)

•

Up : Voltage protection level (V)

•

In : Nominal discharge current (kA)

Ucpv selection •

Ucpv: Maximum DC voltage on the surge protector

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•

Uocstc: DC voltage at the PV generator in open-circuit condition

•

Uocmax: Maximum DC voltage at the PV generator in open-circuit  Uocmax ≥ 1.2 Uocstc

According to the HD60364-7-712 standard, the Ucpv voltage applied to the surge protector must be chosen so as to be equal or larger than Uocmax. In turn Uocmax must be greater or equal to 1.2 x Uocstc* of the PV generator.

for the whole PV system (A) The Iscwpv must be greater or equal to 1.25 x Iscstc of the PV generator.

Iscwpv > Iscstc x 1,25

Up < 0,8 Uw

Exemple : •

System : 6 strings x 12 PV modules in series

•

Iscstc per module = 5,3 A  Iscsct total = 6 x 5,3 = 31,8 Ac

•

Surge protector Iscwpv > 31,4 x 1.25 = 40 A  Citel surge protector DS50PV-600 (Iscwpv = 70 A)

Whatever the modes of protection the surge protector must withstand the Uocmax voltage between its active terminals (+ / -) and the ground.

Ucpv > Uocmax > Uocstc x 1,2

Up selection

Example :

•

Up : Voltage protection level (V)

•

system : 12 x PV modules in series

•

Uw : shock voltage withstand of the modules and inverter (V)

•

Uoc per module=44Vdc Uocstc total=44 x 12 = 528 Vdc

Standards recommend, in compliance with the usual protection rules, that the

•

Voltage Uocmax = 528 x 1, 2 = 634 Vdc

Table 1

•

Uocstc

400 V

Iscwpv Selection •

Iscwpv : Short-circuit withstand (A)

•

Iscstc: Prospective short circuit current

600 V

6000 V

800 V 1000 V

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As data about Uw are never given by the PV equipement manufacturers, the guide proposes an average value for each part of the installation depending on the system voltage. The table below shows the maximun Up value requested and the related Up from CITEL SPDs PV range. Table 1

In selection The HD60364-7-712 standard requires a discharge current In > 5 kA. This means that the surge protector has to withstand 15 impulses with an 8/20µs waveform.

In > 5 kA All the surge protectors from CITEL

Uw PV module

Surge protector voltage> 634 Vdc Citel surge protector DS50PV600 (Ucpv = 680 Vdc)

protection level Up must be lesser than 80% of the impulse voltage withstand (Uw) of the equipment to protect, i.e. the PV modules and the inverters.

8000 V

Up

PV inverter

Required Up voltage (Uw x 0.8)

Up voltage of the corresponding Citel surge protector

3100 V

< 2480 V

2200 V

4200 V

< 3360 V

2800 V

5100 V

< 4080 V

2000 V

5600 V

< 4480 V

2200 V

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DS50PV range have In current values tested and declared above 15kA.

3- SPD Technology Surge protection devices for power systems are based mainly on 3 different technologies: •

MOV or Multi-MOV (Metal Oxide Varistor) (for Type 2 and Type 1 SPDs)

•

Air Gar + Trigger (for Type 1 SPDs)

•

MOV + Gas Spark Gaps (GSG) (for Type 2 and Type 1 SPDs) : VG Technology

The MOV solution is by far the most common technology used for photovoltaic and any other energy network applications.

Nonetheless the installation of these MOVs must be controlled inside a SPD system.

If well chosen as per the application requirements an MOV is perfectly suited for transient overvoltages, surges and other spikes protection.

The latest innovation in SPD includes the use of a Gas Spark Gap component (aka GSG) in series with specific MOV network. We call this patented technology “VG”, for Varistor and Gas Spark Gap. The “VG” technology brings huge advantages and will improve all of the following parameters compared with a basic MOV or Air Gap designs:

1. Excellent Protection level (Up) and Impulse current (Iimp) In the past, such performance was possible only the association of a Type 1 and a Type 2 surge protectors, often separated with coordination inductance.

 « Type 1+ Type 2 » Equivalence

 Maximum Efficiency

 Compact

2. No follow current VG technology does not created « follow currents » during their operations, as « Air gap » technology does.  Improvement of the power distribution (Reduction of the trippings of the up-stream line breakers).

However the MOVs are not suited to resist long (over 10seconds) overvoltage. In this situation the constant excess of energy warms the MOV. The MOV gets hotter and hotter as long as the overvoltage lasts and can ultimately reach a point where fumes and flames appear.

 Improvement of the AC power quality (no micro-power losses)  Easier choice

3.

10/350 µs withstand

All the internal components of the VG protectors used for Type 1 application are designed to conduct heavy surge current like 15 or 25 kA @ 10/350µs.

The «Trigger Diagram by Chiste and Funke in Electronic Systems Protection via air gap » units Advanced Surge Protective Devices are based on To comply standards, the whole design of a triggering circuit built with low power a reliable SPD will prevent these dangerous components: on some conditions, these weak and damageable situations to occur. The components could be stressed by a part of the different disconnection systems located lightning current and could be destroyed. within the SPD will open the MOV circuit Improved reliability if thermal runaway occurs. Higher life expectancy

VG Technology from CITEL 78

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4.

voltage fluctuations could create huge failure on AC installation. If the SPD are sensitive to these phenomena, harsh destruction could also happen. International standards for SPS require minimum withstand to TOVs but VG technology brings much higher withstand (> 450 Vac)  Improved reliability  Higher life expectancy.

5. Status indicators VG Surge protectors are equipped with indicator for the status of the internal protection components (connected/ defective=non-connected). The other technologies are not fully equipped with this kind of feature or the controlled status, if any, is the status of the triggering circuit, not the protection elements.

 Better maintenance.

6. Gas Spark Gap (GSG) VG Surge protectors are equipped with dedicated Gas Spark Gap (GSG). As a manufacturer of GDT (Gas Discharge Tube), CITEL has developed a specific range of components for AC application and High energy behaviour. These components provide steady electrical parameters, whereas Air gaps could vary regarding air pressure or humidity level.  Improved reliability

7. « un-polarized » Varistors in the VG protectors, due to the gas tube connected in series, the varistors are not flown by leakage eing, which could be a problem in some conditions for varsitor-only surge protectors.  Improved life expectancy.

4 - Conclusion We hope this few words about SPDs selection in PV applications have helped you understand more about the selection and technological advantages of SPDs. Nevertheless there are many points of interest that have not could not be raised in this short article such as MOV characteristics, fuse rating selection, protection mode... For clarifications to these questions please feel free to contact us. nnn

Improved TOV withstand TOV (Temporary Overvoltage) and AC

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Changing Global Solar PV Supply Chain Dynamics - Oversupply Woes to Affect Profitability Shaminder Singh Ragi - Associate Project Manager, Solar PV team, GlobalData

The global solar PV supply base is currently going through a transition, owing to a significant capacity addition across PV supply chain. The supply base has grown significantly, while there are indications that the installations growth rate would slow down as leading PV countries cut PV tariffs. However, companies across the PV supply chain have continued to expand their capacity bases. This has resulted in a scenario of oversupply that will trigger changes in the PV supply chain such as market consolidation, inventory pile-up, declining module prices, shrinking supplier margins, technological role-change and changing commercialization strategies for PV players.

Growing Supply Surplus The PV installation base has enjoyed significant growth over last three years. As a response, module companies have ramped up their production capacities. However, the market growth rate is expected to slow down over the coming years owing to tariff cuts in traditionally major PV markets. Given this anticipated decline in growth rate of installed capacity, the current installed production capacity of PV equipment is significantly higher. A comparison of PV module production capacity projections with the PV demand estimations indicates that current production capacity would have to be operated at a 50% utilization rate in order to maintain minimal inventory levels and sustainable

module pricing. If companies fail to contain module supply volumes, falling PV module prices will affect producers’ profitability.

Oversupply Causing Inventory Pile-up Following a tight supply scenario in 2009, module companies continued capacity expansion in 2010 and 2011. Significant capacity additions and capacity utilization to maintain operational profitability have resulted in inventory pile up. If tier-1 companies sustain their shipment guidance for 2011, module shipments are expected to be about 125% of expected demand by the end of 2011. Moreover, the scenario is expected to continue into next year unless

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production cuts are implemented. Given the current rate of production and capacity addition, the year-end module inventory for 2012 could reach about 60-70% of 2013’s expected demand. However, a significant capacity addition in emerging markets such as India and China could bring down the inventory pile up levels.

Shipment Growth Outpacing Revenue Growth A comparison of change in shipments with change in revenues between Q1 2011 and Q2 2011 indicates that the shipments for companies have shown significant increase.

However, the revenues have not shown corresponding increase. The companies in quadrant one, Q-Cells, Yingli Solar, SunPower, Trina Solar and Canadian Solar, have been able to register growth in their revenues as well as shipments. Q-Cells and SunPower have been able to register a higher percentage increase in their revenue than their shipments owing to their integrated operations. Q-Cells has been involved across the PV supply chain while SunPower has been selling modules as well as providing project development services.

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products in a market where proven module technologies are available at competitive prices. Companies are hedging risks by focusing on improving the performance of existing PV module technologies rather than introducing new products in an oversupplied market, unless these products have significant cost advantage.

Trina Solar, Yingli Solar and Canadian Solar have registered higher growth in shipments compared to the growth in their revenues.

Trina Solar and Yingli Solar have increased their shipments by more than 20%. However, these companies have not been able to achieve similar growth in revenues owing to a decline in module prices and competitive market scenario. First Solar and Suntech fall in second quadrant, which indicates a decline in revenues despite an increase in shipments. These companies have also been affected mainly by a price decline owing to a competitive market scenario.

competitively price their modules in order to retain market share, a practice that has brought the margins under pressure. JA Solar has already registered a negative gross margin, and a further decline will result in other companies following suite. In order to sustain such a decline rate, companies will have to focus on reducing operational costs.

In addition to this change in research strategy, tier-1 companies are distinguishing their modules as high-quality products that offer better returns and assurance. These companies aim to project themselves as premium brands with more expertise in order to gain an edge over emerging new players.

Market Consolidation Given the oversupply scenario and strong brand presence of tier-1 players, tier-2 players in solar PV supply chain are finding it difficult to offer high-quality modules at

Declining PV Module Prices and Shrinking Supplier Margins The table below compares the yearon-year change in the revenues to shipment ratio of primarily module companies. The ratio shows significant decline owing to a sharp fall in module prices, which has been primarily driven by an oversupplied market.

The oversupply scenario has resulted in increased market competition for limited demand, forcing companies to reduce their prices in order to win contracts. While this scenario is expected to be beneficial to PV project developers, the price decline in this scenario has been driven by increased market competition and not by improved project economics. Hence, such a decline rate is not sustainable in the long term.

An oversupplied market and the inventory pile up have forced module companies to

Refocusing on Cost Reduction and Brand Development The quick emergence of PV players with production capacity in low-cost production destinations such as China and Malaysia has commoditized solar PV modules and introduced a significant inventory into the market. This has resulted in oversupply of PV modules and a higher-than-anticipated decline in prices. In this scenario, companies have been forced to refocus their strategy towards reducing costs in order to maintain margins. This has narrowed the scope for innovation and development of new

lower costs. Such companies will eventually lose out on their anticipated market share to tier-1 companies. In such a scenario, tier-2 companies would look for opportunities to sell their operations and associated contract pipelines resulting in consolidation of PV supply chain. Industry players have also begun to expand their operations vertically to improve their overall margins. Top tier-1 players have recently begun to provide project development services in order to hedge the risks involved in exposure to module price fluctuations. These moves by companies across the PV value chain are expected to usher in the consolidation of the PV market, thus offering better controlled supply in the oversupplied market.

Changing Role of ThinFilm Technologies Thin-film technologies were championed as next dominating PV technologies in 2010.

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The technologies were estimated to gain a significant market share of PV installation base over next few years. However, the significant decline in crystalline PV module prices and an oversupplied market have raised the entry barriers for novel thinfilm technologies. Most of the thin-film technologies, with an exception of First Solar, have been losing their market share to tier1 crystalline module companies. In such a scenario, these thin-film companies would be forced to look for alternative markets such as BIPV and commercial applications. Moreover, thin-film market players would be required to reduce their costs at a faster rate in order to offer a significant cost advantage, if they are to compete with established crystalline PV players in the market. Given current price trends for crystalline modules, thinfilm modules are unlikely to gain significant market share from crystalline PV module companies in the near term.

Key Industry Developments Defining Trends

•

Companies are forming partnership to reduce cost and gain strategic advantage

Solar Semiconductor to acquire PV module company Solar Infra

•

Mitsubishi acquires stake in silicon wafer manufacturer Utech Solar

•

Veeco Instruments to exit CIGS thin-film PV systems business

•

Abound Solar partners with Thesan to reduce photovoltaic installation costs and complexity in Italy

operations in face of rising market competition

•

Abound Solar enters partnership and distribution agreement with DW Europe for commercial projects

•

BP Solar to close its solar panels manufacturing facility in Frederick, Maryland

•

OSM Solar forms strategic partnership with Solarform Canada to expand operations in North America

•

TOTAL to acquire remaining 50% stake in Tenesol

•

Suntech and MEMC terminate long term silicon wafer supply agreement

•

Arista Power enters strategic partnership with PV module manufacturer Helios Solar Works

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Companies restructuring or exiting

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EQ provides unique Insights & Transparency in Power Generation, Clean Energy, Low Carbon Technologies, Carbon Markets. Latest Industry Information, News, Research & Analysis, Technology & Products Information, Business & Financial News, Policy & Regulation is delivered to an interesting diverse readership base in Energy Corporations, Government, Policy Makers & Regulators, Consultancy & Advisory Firms, Associations, Banking & Financial World

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* PLATFORM : EQ offers a diverse & integrated platform with its Bi-Monthly Technical Magazine (Distributed in Print & Digital Formats), Special Supplements addressing Specific industry, Weekly E Newsletters, Diverse Digital Publishing with its appearance on Web, iPad, Kindle, iPhone, Blackberry, Android Platforms (COMING SOON) along with strong emphasis on Social Networking @ Facebook, Twitter to enhance your reach, visibility, branding and addressing the issues you feel are most important. * REACH : EQ Maintains a strong focus on the Indian Market from where it is published with 12,500 Copies distributed to Key Decision Makers. Approximately 2500 copies are printed for Select International presence. Its unique and strong digital presence (Distributed to 90,000 Contacts) takes it beyond borders and get popularity in International Market. * PRESENCE : EQ is present in almost all Fair & Conference in India and the Most important International Events.

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Nanotechnology in the Solar Industry Avinash Iyer, Technical Insights Senior Research Analyst for Energy & Power Systems, Frost & Sullivan.

Technological improvements in terms of performance and manufacturing cost reduction have made solar cells an increasingly viable form of renewable energy. Of late, use of nanotechnology and nanomaterials such as nanotubes has accelerated the growth of high performance solar photovoltaics.

R

educed manufacturing costs due to low temperature process and reduced installation costs achieved through flexible rolls could be cited as foremost reasons for increasing popularity of nanotechnology in the solar industry. As a result, solar has been a buzz word within the semiconductor and energy industry, with strong and sustainable year-on-year growth being predicted for the coming years.

Technologically, third generation solar cells such as dye-sensitized solar cells (DSSCs) are entering the market. Promising low cost and being environmentally friendly photovoltaics such as DSSCs are widely seen to be viable especially for in-built solar panels.

Baby Step Improvement In Solar Photovoltaics Using Nanotechnology Collaboration and augmentation are the foundational principles of innovation.

The improvisation of solar photovoltaics using nanotechnology is predominantly due to the incremental and cooperative enterprise between Industrial and Research organizations. This cross-breeding of technology has led to baby step improvement in the performance of solar photovoltaics.

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Using Nanofibers

of standard flat organic panels. However,

Wake Forest University is researching on the boosting efficiency of organic solar panels by implementing an antireflective coating on the organic solar panel surface. In this system, optical fibers and a polymer substrate constitute the foundation of the cell. These optical fibers will act as a trap for the solar radiation, which will keep bouncing inside the panel till it is absorbed by the cell organic material. Optical fibers protrude from the cell foundation surface and are surrounded by organic solar cells, which are placed there using a dip-coating process. In addition, the special layer with light absorption abilities is sprayed on the surface of the cell. Such a solution ensures light absorption from any angle, which is another advantage of this technique. This would boost the organic solar panelâ&#x20AC;&#x2122;s efficiency beyond 10% (Standard efficiency of the organic flat cell is about 6% to 8%). On successful completion of such research efforts, organic solar cells will have the chance to compete against silicon solar panels--the most efficient solar panels currently in the market.

Cost of production of the optical fiberbased organic panels will be the same as that

investment for building the facility for manufacturing fiber-based solar panels will be ten times lower in comparison to that of standard silicon panels. This will decrease the overall panel price, making it cost-effective than silicon cells.

Using Nanowires Georgia Institute of Technology in Atlanta, Georgia recently conducted its research in double power generative device where both solar and piezoelectric energy from movement or vibrations. Using arrays of zinc oxide (ZnO) nanowires grown on the surface of a flat silicon substrate, a thin-film solar cell embedded with dye-coated zinc oxide nanowires is built on its top surface, and a piezoelectric nanogenerator is built on its bottom surface. The silicon acts as both the anode of the solar cell and the cathode of the nanogenerator. The ZnO nanowires for the nanogenerator are grown on gallium nitride (GaN) substrate. The prototype cell has been successfully demonstrated to work on solar and ultrasonic wave energies individually or simultaneously.

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This development is the first known double power generation device. The innovative and interesting concept is likely to inspire other researchers to work on hybrid devices to harvest multiple energy sources or on nanogenerators. Nonetheless, improvements of the power and voltage output of would be crucial to enable the technology to move beyond the laboratory.

Using Nanoparticles A*Star, Singapore in collaboration with the CSIRO Material Science and Engineering, Australia, conducted a study on the performance of thin film silicon solar cells with silver nanoparticles. The research study revealed that metallic nanostructure in very thin silicon solar cells can enhance light absorption and thus increase the performance of thin film solar cells. Nanoparticles acting as tiny mirrors concentrate light better than conventional mirrors. This effect is based on surface plasmons, the collective motions of electrons at the nanoparticle surface. Surface plasmons intensify the incoming light and focus it in to the silicon layer.

Thus the light absorption capacity is significantly improved. Larger nanoparticles p r ov i d e b e t t e r enhancement through optimized p a r a s i t i c absorption in the nanoparticles and such enhancements are not limited to plasmonic nanoparticles. On the other hand, dielectric nanoparticles such as silicon carbide that has high-dielectric permittivity lead to similar and even few times higher enhancements.

Enhancement caused by deposited metallic or dielectric nanoparticles are very sensitive to their shape and arrangement. It may be difficult to optimize all the parameters simultaneously. However, a fraction of the surface coverage area may be sufficient for enhancement of a thin film. Although research is still in its infancy stage, thin film silicon

solar cells with nanoparticles are a promising alternative. However, much research is needed to enhance the efficiency of these solar cells through further optimization of metallic nanostructures. Furthermore, the combined use of different metals could also lead to enhancements over a broad range of wavelengths and thus create a breed of better third generation solar cells. The market can expect such thin film photovoltaics in the next two or three years.

Reduced Manufacturing Costs Using Nanotechnology Flexible electronics technology has advanced to the stage where inexpensively printing high-performance devices on continuous rolls of polymer-based substrates now promises to revolutionize advanced manufacturing. The future industrialization of this technology naturally requires

scaling system properties while retaining the collective properties of the nanoscopic elements over macroscale dimensions.

Meeting this challenge is a key to high-rate manufacturing of nano-enabled products and for establishing viable industrial-scale manufacturing platforms for continuous large-area roll-to-roll processing. A relatively new start-up company, Rolith Inc. (Pleasanton, CA), has been developing a new concept of nanolithography for large-scale production of advanced products, such as high-efficiency nanostructured solar cells,

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building-integrated photovoltaic cells, flat panel displays, and LEDs. The company proprietary â&#x20AC;&#x2DC;rolling mask lithographyâ&#x20AC;&#x2122; method produces nanostructures on square meters of rigid or flexible materials.

Rolling mask nanolithography is a fast and massively parallel patterning method, easily scalable to the large-area substrates, which allows controlling the distance between a mask and a substrate accurately, and seamless scaling of the exposure process to large-substrate areas.The availability of such a high-throughput cost effective nanolithography method for nanostructuring over large areas of substrate materials could bring new possibilities to renewable energy and green building markets in the next couple of years.

The Road Ahead Solar photovoltaics are now used widely used in various applications. It has been observed that most of the solar photovoltaic cells experience several challenges. The challenges such as rain water logging, snow deposition, corrosion reduce their efficiency and capability. To provide a solution to this industrial shortcoming, it is necessary to develop a solar cell technology, which would help perform better. A mere 1 percentage point increase in solar cell efficiency can have a very big impact on the overall energy output of the system and thus on investment payback time. Adoption of nanotechnologies during the production or installation will help the solar industry.

Despite showing promising performance, it would take at least another five years for any nanotechnology based solar panel to commercial, as most of them are still in their infancy stage of development. nnn

EQ INTERNATIONAL November/December 11

83Â

SO L A R ENERGY

The IEA Photovoltaic Power Systems Programme

T

he International Energy Agency (IEA), founded in 1974, is an autonomous body within the framework of the Organization for Economic Cooperation and Development (OECD). The IEA carries out a comprehensive programme of energy cooperation among its 26 member countries and with the participation of the European Commission.

The IEA Photovoltaic Power Systems Programme (IEA PVPS) is one of the collaborative research and development agreements within the IEA and was established in 1993. The mission of the programme is to “enhance the international collaboration efforts, which accelerate the development and deployment of photovoltaic solar energy as a significant and sustainable renewable energy option”.

As part of the work of the IEA PVPS programme, annual surveys of photovoltaic (PV) power applications and markets are carried out in the reporting countries. The objective of the series of annual Trends reports is to present and interpret developments in both the PV systems and components being used in the PV power systems market and the changing applications for these products within that market. These trends are analyzed in the context of the business, policy and non-technical environment in the reporting countries. The following is an excerpt from the latest Trends report, specifically addressing the activities of electricity utilities with regard to PV. Worldwide, electricity utilities are now investing in very large-scale PV plants or

84

EQ INTERNATIONAL November/December 11

asking how they can benefit from meeting their customers’ interest in PV plants or PV electricity, often driven by government mandates and increasingly leading to the pursuit of business opportunities. Part of this development in the near to medium term is being integrated with an increased focus on more intelligent electricity networks, the need for a more widespread deployment of electricity storage technologies and new markets for electricity such as charging of electric vehicles. These issues provide benefits, opportunities and challenges for electricity utilities and regulators. Diverse electricity utility PV activities are reported by the PVPS countries, and an outline of these activities follows.

In the past, Australian electricity utilities were heavily involved in PV demonstration programmes through their own R&D arms.

More recently, electricity utility interest has largely been driven by government programmes, such as the Solar Cities and, to a lesser extent, Smart Grids programmes.

All electricity retailers are liable under the Renewable Energy Target and some have installed their own PV systems to contribute to meeting their liability. Some utilities have also established solar businesses and retail PV systems to their customers. An electricity utility has purchased concentrating solar PV power stations and operates them to provide power to isolated communities.

In Canada, some utilities have developed and implemented programmes that streamline net metering approaches and set out approved tariffs. The Danish transmission system operator, Energinet.

dk, has for several years expressed interest in PV as a potential contributor to electricity supply and in support of the electric grid.

The distribution utilities, most notably EnergiMidt, have also promoted the use of PV and since 2009 several distribution utilities have included PV technology in their portfolio of products. Most distribution utilities simply regard PV as a relevant standard product and some offer finance packages and payment via the electricity bill. Interestingly, in Germany where the regulations of the EEG are so successful in eliminating barriers and in stimulating private sector investment, the electricity utilities play a subordinate role. The Israel Electric Corporation (IEC) takes a mainly technical role in support of the government’s feedin tariff, and has published a considerable amount of technical information for the public and for the installers.

In Japan, electricity utilities introduced the Green Power Fund in October 2000 to promote the dissemination of energy sources such as PV. Over the period 2001 to 2010 the fund supported PV installations at 1 568 places nationwide, with a total capacity of 27,6 MW, mainly at public facilities such as schools and hospitals. However, with the commencement of the government’s New PV Power Purchase Programme in late 2009 some utilities including Tokyo Electric Power Co., Inc. (TEPCO) have scrapped the voluntary Green Power Fund. Electricity utilities have also purchased the required amounts of electricity generated from new and renewable energy under the Renewable Portfolio Standard (RPS) Law. Looking

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ahead, electricity utilities have formulated plans to construct PV power plants located at 30 sites with a total capacity of 140 MW across the nation by 2020 and have also started introducing PV systems at their own facilities.

as a demonstration project. The interest from the electricity utility business in PV is rather low in Sweden, except for Sala-Heby Energi AB which offers a local feed-in tariff scheme for a local PV community Electricity utility interest continues to increase dramatically in the United States, with the key drivers being policy - the federal tax credit (30 %) at the national level and Renewable Portfolio Standards at the state level. Four broad categories of utility solar business models have emerged in the US: utility ownership of assets, utility financing of assets, development of customer programmes, and utility purchase of solar output. Utility ownership of assets allows the utility to take advantage of the tax policy benefits and earn a rate of return on the asset (for investorowned utilities), while providing control over planning, siting, operating, and maintaining the PV facilities. Utility Financing of Solar Assets is a PV business option for utilities that do not choose to own solar assets for tax, cost, regulatory, or competitive considerations. To

Six Korean electricity generation companies have signed the RPA (Renewable Portfolio Agreement) with the government in order to increase the share of renewable energy in electricity generation. From 2012, the RPS (Renewable Portfolio Standard) will replace the feed-in tariff scheme. Thirteen companies are planned to participate in the RPS, which should realize 1,2 GW installed capacity of PV by the end of 2016. A clear declaration of interest in PV technology has been sent by the Mexican national electricity utility in 2010 with the installation of a grid-connected system at the offices of the General Director, and planning for MW size PV system underway. In 2010, Malaysia’s Tenaga Nasional Berhad (TNB) has issued a call for tender for a 5 MW PV power plant

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be successful, regulators treat the financing and lost revenue costs associated with a solar project as assets, allowing the utility to earn a rate of return on ‘investment’. Customer Programmes are designed to increase access to solar energy by lowering costs, for both the utility and the customer, compared to a traditional customer-sited PV system.

Community solar programmes involve a community or centralized 0,1 MW to 20 MW PV system and specific classes of participating customers to whom a proportional share of the output can be allocated, offsetting their electricity bill directly or by offer of a fixedrate tariff that is competitive with retail rates or will be in the near future as electric prices increase. Utility Purchase of Solar Output is a business model often applied by publically owned utilities to create value to their communities through local solar development. Some publicly owned utilities have developed a feed-in tariff to purchase PV electricity.

E-mail: ms2@

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ndia Pradesh,I .in , Andhra yahoo.co d-500062 henergy@ , Hyderaba E-mail : daks m, ECIL Post - 27162719 W, Annupura HO : #95/ Telefax : 040 3 29900 +91 9885 : ile Mob

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EQ INTERNATIONAL November/December 11

85

REN EWA BL E ENERGY

Renewable Energy Certificates – Status & Way Forward Balawant Joshi, Founder Director, ABPS Infrastructure Advisory Pvt Ltd.

I

ndia has been at the forefront of development of renewable energy in the world. According to World Energy Outlook 2011 published by International Energy Agency India has fifth largest renewable energy capacity in the world.

This development has been result of the progressive policies developed and adopted

by Indian Government over last two decades.

India developed its first major feed-in tariff policy way back in 1993-94. The said policy was called as ‘buyback policy’. Since then several other policy instruments such as capital grants, accelerated depreciation, interest rate subsidies, sales tax and other tax exemptions, renewable purchase obligations, etc have been implemented.

Over last one decade, cliamte change debate has reached its crescendo. Pressure has been mounting on both developed and developing countries to take stroner action to mitigate GHG emissions and limit global warning. Though India is not obliged to commit to GHG mitigation actions, Hon. Prime Minister of India on June 30, 2008 announced National Action Plan for Climate Change (NAPCC) which envisages several measures to address global warming. The NAPCC has identified increasing the share of renewable energy in total electricity consumption in the country as one of the important measures to combat climate change. NAPCC has set the renewable purchase obligation of 5% of total electriicty generation for FY 2009-10. Further, NAPCC envisages that the target to increase by 1% for next 10 years to reach 15% by 2015.

Genesis of Renewable Energy Certificate While India is blessed with vast amount of renewable energy sources, these sources 86

EQ INTERNATIONAL November/December 11

are unevenly distributed across the county.

While wind is concentrated in eight states in southern and western part of the country, solar is concentrated in western parts of the coubtry and hydro is concentrated in northern, north-eastern parts of the country.

Some of the states such as Delhi, Madhya Pradesh, Jharkhand, Orissa have very little renewable energy potnetial. If entire country has to take responsibility for development of renewable sources, it is necessary that renewable electricity is procured by all states irrespective of potential on their own land.

This would require purchase of renewable energy across the state boundary.

However, open access methodology prescribed under the Electricity Act 2003 made renewabele energy sale and purchase contract across the State boundary very expensive. Further, contracting of small quantity of renewable power was extremely difficult. To complicate the matter, banking is not permitted under EA 2003.

Whatever may be the mode of procurement of renewable energy by State other than the one where project is located, technical risks such as state level imbalances, spinning reserves, fault currents, etc will have to be borne by the host State as power will have to be absorbed in local grid. As a result, host states are not keen to encourage significant purchase of renewable energy.

While technical solutions are available and need to be deployed to mitigate these technical risks, commerical risks pose greater threat and need to be resolved in a manner so as to long term sustainability of the solution.

With this background, Renewable Energy Certificate (REC) mechanism was developed. It essentially seeks to address the mismatch between availability of RE sources

and the requirement of the entities obliged to purchase renewable to meet their renewable purchase obligation across States. So far inter-State exchange of renewable energy was constrained due to the fact that such transactions are governed by inter-State open access Regulations and the regional energy accounting framework, which necessitates scheduling of power. Some of the RE sources such as biomass power or bagasse based co-generation can be scheduled and interState open access transactions based on such firm RE sources have taken place in the past, however, inter-State exchange of power based on non-firm RE sources such as wind energy, solar power, small hydro power, etc., was constrained. Besides, the cost of open access wheeling under long term arrangement was prohibitive for such non-firm RE sources due to their inherent lower capacity utilisation factors.

Effective implementation of inter-state transactions is the primary objective of the REC mechanism in India. Other objectives being; reducing costs for RE transactions; increasing flexibility for participants in RE transactions; overcoming geographical constraints; effective implementing of RPO regulations in all Indian states; creating competition among different RE technologies; reducing risks for local distribution licensees, etc.

What is Renewable Energy Certificate?

In this mechanism, RE generator sells two independent and exclusive products from the same quantum of RE generation. These products are electricity and its associated environmental attributes in the form of RE Certificates. Fig. 1 presents the REC mechanism.

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Under the REC Mechanism, the Renewable Energy Certificate or REC represent 1 MWhr of generation of electricity from qualified renewable energy sources. The RE generator may sell electricity to the distribution company at its weighted average pooled cost of power purchase approved by the concerned SERC for and associated RECs to any buyer at market price through REC exchange in a transparent manner. The RE generator may sell the certificates not to obligated entities but also to voluntary buyers. The purchase of RECs is deemed as a purchase of power generated from renewable sources and accordingly is allowed for compliance of the Renewable Schematic of Operational Framework for REC Mechanism Purchase Obligation under Section 86(1) (e) of the Electricity Act 2003. The REC mechanism enables obligated entities in a State to procure RECs generated in any other State in India and surrender the same to satisfy the RPO target.

Experience till date

Fig. 2

Up till now, the total RECs issued in the country are 358180 and RECs redeemed are 221101. REC prices have increased sharply, mainly as a result of the large demand-supply gap (demand August was 183,000, supply was 58,000). Taking into consideration the trading session in the month of October 2011, there was increase in volumes (95,504 RECs sold in the month October as compared to 46,362 of September 2011, which is almost double) and price of Rs 2710/ REC as compared to the price of Rs 2300/REC in the month of September. Thus, trading in RECs has been picking up briskly both in volumes and in prices. Fig. 3

Fig. 1

The schematic depicted in figure below represents a flow diagram for various processes involved in REC mechanism. The numbers indicate the chronological sequence of key processes. Fig.2 The operational framework depicted above does not envisage any major modification to the existing arrangements for renewable energy procurement. The framework entails appointment of an agency at national level to facilitate the registration of eligible RE generators, issuance of RECs and maintenance of record of procurement of RECs by Obligated Entities.

RECs are generation-based ‘certificates’ awarded electronically, in demat form to those generating electricity from renewable sources such as wind, biomass, hydro and solar, if they opt not to sell the electricity at a preferential tariff determined by the regulator. Trading in RECs takes place on the last Wednesday of each month, and if that day happens to be a holiday, then it takes place on the next working day.

In August’s REC trade, both prices and demand volume increased significantly from last month. REC demand in July was about 96,000, it almost doubled to over 183,000 in August. This is perhaps the most significant indicator for the REC markets, as it points to a strong expectation of RPO enforcement by market participants this year. With demand expected to increase significantly as we approach March 2012, the demand supply gap is only expected to widen, particularly as more captive and open access generators join the market. The figure below presents the REC Volumes on two Power Exchanges.

Thus, while the growth in cleared volumes and prices is encouraging, the flipside is the skew in the demand-supply scenario. Supply is growing way too fast compared to the demand. This brings into focus the important issue of what needs to be done to deepen the REC market.

Fig. 4

Fig. 3

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EQ INTERNATIONAL November/December 11

87

As on October 2011, the accredited projects in the country are 290 with a total capacity of 1775.2 MW. The graph below presents the technology wise status of the accredited projects. Fig. 4 As on October 2011, the registered projects in the country are 220 with a total capacity of 1449.8 MW. The graph below presents the technology wise status of the registered projects.

ability of obligated entities to enter into long term purchase transactions. There is a need to encourage long term bilateral transactions of the RECs as these transactions provide price stability to the market. Further, obligated entities upon exceeding their RPO targets, should be allowed to participate in REC transactions for their surplus RECs.

Lack of intermediaries in the market

has been implemented in the country, Feed in Tariffs are continuing. Initially, FITs were continued to avoid abrupt shift to REC Mechanism which could have caused disruption in market. However, as FIT provides more stable regime, most utilities as well as generators are preferring FIT regime over REC. Since REC Mechanism creates competition for electricity as well as for environmental attributes, it has better potential to create competitive market.

In order to esnure sustainability of REC market, feed-in traiffs may be abolished for established renewable energy technologies such as wind, small hydro, biomass, etc. FITs may be continued for other technologies such as solar, geothermal, ocean, offshore wind, etc.

Voluntary participation in REC market

As one would expect, wind is the leader of the market with maximum number of projects worth capacity of 645 MW, followed by bio-fuel cogeneration with 407 MW, followed by biomass and lowed of small hydro with 56.5 MW.

Future Developments Renewable Energy Certificate mechanism is the first market based mechanism in India which trades in green attributes. While this market has been running successfully for last eight months, by no means it is perfect.

Several issues are associated with the REC Mechanism. Inability of REC mechanism to ensure financial closure of new projects, shallow market with limited players, lack of visibility of floor and ceiling prices, and lack of understanding about REC Mechanism are some of the issues hindering development of REC market. However, as discussed below, it is possible to address these problems and create robust REC Market.

Lack of bilateral market Currently, trading in RECs is restricted to CERC approved organized trading platforms.

As a result, generators are not able to assign / securitize RECs to raise money for new projects. Lack of bilateral trade also hinders 88

Under the present REC Mechanism, as soon as the transaction takes place on the power exchange, RECs are redeemed. REC can traded only once. As a result, there is no role for intermediaries, who typically play a role of market makers, Banks/ lenders cannot acquire and then sell RECs. Since compliance is yearly, transactions are bound to take place towards year end. As a result, cash flows of the generator would get skewed towards year end, severely affecting his ability to make regular debt related payments. In order to overcome this hassle, multiple trading of RECs should be permitted. In order to esnure transparency it may be made mandatory to register every trade with the Registry.

Similarly shorter compliance periods may be considered.

Uniqueness in REC Obligated Entity should be permitted to purchase both REC and the electricity from the same RE Generator. This is better option than issuing RECs to Obligated Entities as it automatically creates liquidity in REC market. Long term bilateral trading of RECs ensures the long term off-take of RECs which enhances the bankability of RE projects.

Abolition of FIT mechanism Currently, though REC Mechanism

Several responsible corporate, commercial undertakings might be interested in purchasing RECs so as to reduce their carbon foot print. This could be good branding strategy for these entities. It is necessary to encourage such participants.

Further, development of voluntary ‘Green Tariffs’ by Utilities would encourage small LT Consumers to purchase renewable energy.

Utilities could purhcase renewable energy required for ‘Green Tariffs’ through REC market. Similarly, off-grid RE generation could be integrated into REC Mechanism so as to internalize the costs of rural electrification, better monitoring of the generation and ensure long term viability of off-grid schemes

Conclusion India has established thriving market for Renewable Energy Certificates. The market has been designed to suit unique Indian requirements. Every effort need to be put to remove problems faced by this mechanism.

Balawant Joshi is Founder Director of the consulting company ABPS Infrastructure Advisory Pvt Ltd. He has nearly two decades of experience in the energy sector in India and abroad. He has been deeply involved in conceptualization, design, development and implementation of Renewable Energy Certificate Mechanism in India. nnn

EQ INTERNATIONAL November/December 11

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89

REN EWA BL E ENERGY

Power Electronics Packaging Revolution

Module without bond wires, solder and thermal paste Peter Beckedahl, Manager Application and Concepts, Semikron

Power module packaging is driven by the ever increasing demand for higher power densities, reliability improvements and further cost reductions. The known reliability limitations of tradi-tional solder joints and bond wires are holding back significant power density increases made possible thanks to higher junction temperatures and the future utilization of wide bandgap de-vices. Today, silver sintering has already started to replace the solder joint between chip and DBC substrate, leaving one major reliability bottleneck: the bond wire interface on the chip surface.

F

or some years now,the elimination of bond wires in power modules has been under discussionin industry and academia. Most of the new packaging approaches have been based on soldered or welded bumps,as well a son embedded interconnection technologies.

The innovative packaging technology, named SKiN Technology, presented here takes the Ag sinter joint and applies it to all remaining interconnections in a modern power module.

In addition to the double-sided sintering of power chips, the entire DBC is sintered to the heatsink. The resulting device has a very high power density and demonstrates remarkable thermal, electrical, and reliability performance compared to traditional packaging technologies.

However, two issues remain unaddressed: how to replace wire bond-ing on the chip topside, and how to connectthe power module to the heat sink.

SKiN Technology resolves both these matters by using Ag sinter technology for all interfaces. The chip surfaces are sintered on the top side to a flexlayerand the chip bottom to a DBC substrate, which in turn is sintered to a heat sink or base plate.Fig. 1 shows a schematic drawing of this packaging technology.The special flex foil has a metal base power layer which is comparable to bond wire diameter in thickness and serves to connect the chip top surface. Athin metal

layer on top represents the gate and sensor tracks which are connected to the power layer by vias. The two metal layers are insulated from each other by polyamide.The top layer can also be used for SMD components such as temperature sensors and gate resistors.

The second sinter joint connects the back of the chip to a standard DBC substrate. All standard IGBT and diode chips can be used for this process, they need just an additional noble metal contact treatment on the chip top side.

The third joint connects the back of the DB Cusing large-area Ag sintering to an aluminum pin fin water-cooled heat sink.The

Sinter technology Silver sintering is an established technology which has started to replace the soldering of chips to DBC substrates in mass production. Thanks to its unprecedented reliability and thermal behavior, it makes power modules better suited to higher temperatures and demanding applications such as elec-tric vehicles and wind turbines.

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EQ INTERNATIONAL November/December 11

Figure 1.A schematic drawing of SKiN device.

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power terminals are sintered to the DBC in the same process step, resulting in a power module in which all interconnections are made with Ag sinter joints.

The main advantages of the new SKiN Technology and its performance improvements are as follows:

275A, 600V CAL freew-heeling diode per switch. The power terminals are placed on the opposing short sides of the heat sink.The auxiliary contacts from the IGBT to the gate driver are provided by the flex layer itself, which is extendedacross the long side of the DBC (see Fig.2).

• Power Density: The use of an Ag sinter layer instead of thermal paste will increase the power density as a result of the reduced thermal resistance chip to coolant. The large-area metal connection on the chip top surface will further improve the heat spread of the die.

• Reliability: The replacement of Al bond wires by sintered flex foil will increase the power cycling capability thanks to better CTE compatibility of the materials used,and the large-area connection between chip surface and contact medium.

• Electrical Properties: The use of the sintered flex foil instead of the Al bond wires will increase the maximum surgecur-rent rating of the dies as a result of the increased cross-section and area of the chip surface con-tact. In addition the module stray inductance is decreased due to a reduced loop geometry and wide traces.

Power Module Design The prototype design used for this performance comparison is a 600V, 400A half-bridge power module with an aluminum pin fin heat sink.

The chipset of the prototype samples consist of 2 x 200A, 600V IGBT and 1 x

Fig 3. Benchmark module with bond wires

In order to benchmark the new packaging concept not only with traditional power module designs, identical devices have been built with standard Al bond wires for the die surface contact. To obtain maximum performance, each chip is contacted with 12 bond wires (see Fig. 3). The surface of the diodeis contacted with 3 stitches per wire; the IGBT with 4 stiches.

A significant difference between the flex layer and bond wire design is the contact area of the chip surface. While the bond wires are in contact with around 21 percent of the total metalized chip area on-ly,the flex design exhibits a contact area of 50-85 percent, depending on the chip type.

The maximum power dissipation of the semiconductors is limited by the maximum junction tempera-ture, the coolant temperature and the thermal resistance from chip

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PV =

(T j − Ta ) Rth ( j − a )

Especially in automotive applications where coolant temperatures above 85°C are needed the temperature difference to the maximum allowed junction temperature becomes small which leads to re-duced power densities and the need to reduce the thermal resistance to a minimum.

The new power module meets these requirements with a fitting solution: a high-density pin fin Al heat sink and an Ag sinter joint between the DBC substrate and the heat sink. No thermal paste is used, which has a significant contribution in the thermal performance of standard packages.

The measurements were performed using a three-phase automotive inverter setup (Fig. 4) with a 50 percent glycol mixture and 70°C coolant temperature. The water inlet and outlet is on the left-handside; distribution through the three modules is obtained using

Figure 4Inverter setup used to measure thermal resistance

Thermal Resistance

Fig 2.SKiN half-bridge 600V, 400A module

to cooling medium.

three parallel flow channels.

For the test all IGBTs are electrical connected in series and heated by an adjustable DC current. In this way it is possible to measure the power losses as well as the junction temperatures most accurate since it is not disturbed by switching transients.

EQ INTERNATIONAL November/December 11

91

The difference in thermal resistance (junction to water Rth(j-a)) between the upper (TOP) and lower (BOT) IGBTs, as well as the variation between the half-bridges is less than 10 percent and is shown in Fig. 5. The lower switch of a half-bridge has a slightly better thermal resistance than the

Figure 5 Rth(j-a) of the six IGBT switches

Table 1 Summary thermal resistance

upper switch. This is down to the larger DBC copper area beneath these chips which leads to better thermal spread. This effect is well known in power module designs due to layout restrictions.

A summary of the thermal results is given in Table 1.The total thermal resistance

Rth(j-a) is exceptionally good, while the pressure drop remains at a very low level.A figure of merit is given in the second col-umn were the thermal resistance is multiplied by the total chip area. This figure can be used for an easy comparison to competing solutions.

At a coolant temperature of 70°C, a flow rate of 10l/min and a maximum junction temperature of 150°C, it is possible to draw 205 W/cm2 chip area out of the system.

Traditional high-power inverters with thermal paste between the power module and the water cooler reach just 100-150 W/cm2 chip area. Please note that the flow rate in Table 1 is given for 3 half-bridges with parallel water paths. The flow per halfbridge is only one third of the total flow rate.

Of course it is also possible to arrange the design with a serial coolant flow through the three phases which will lead to an even higher power density.

The question remains as to how a traditional module would perform if it were mounted on the same high-density Al pin fin cooler used for the SKiN module.

To investigate this, thermal simulations were performed where the Ag sinter joint between DBC and heat sink was replaced by a thermal paste layer of only 20µm. Such a thin thermal paste layer is only possible using sophisticated pressure contact modules without baseplate, like the SKiiP or SKiM power module family. Modules with baseplate would require a much thicker thermal past of 80-150µm.

The simulation results confirmed the large impact that the thermal paste layer has. Even for a layer of just 20µm, the total thermal resistance will increase by 23-30%, depending on the coolant flow rate.

Surge Forward Current The diode surge forward current (IFSM) was measured using a standard half sine wave current surge of 10ms duration at 25°C. The results for maximum peak current level before destruction are displayed in Table 2.

The surge current rating of the flex layer module is 27 percent higher than the bond wire module.

Table 2 IFSM comparison

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Due to the larger cross-section andshorter track lengthin the flex layer design, the surface contact fus-es later than the bond wire module.

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This behavior is particularly important for active front-end or generator applications, since it compen-sates for the reduced chip area which has been made possible from the improved thermal behavior of the integrated pin fin cooler.

Power Cycling Power cycling is the main qualification test to validate the lifetime required by the application mission profile owing to cycling loads. The most demanding applications are electric and hybrid vehicles, ele-vators, as well as wind turbines. The failure modes for power cycles are a combination of the typical bond wire lift-off and solder joint degradation in the layers below the chips.

What cause of failure do-minates depends on numerous factors such as cycle time and chip size. The replacement of the sold-er with a sinter layer has already eliminated one failure mode, leaving only the bond wire as the re-maining reliability weak point.

Single-sided sintered power modules have already in the past demon-strated a 2-3 fold improvement in power cycling.

Power cycling testswere performed on both module types under identical conditions with ΔTj= 110K (40°C to 150°C) and a complete cycle times of 14 seconds The control strategy for the power cycling test was a fixed time adjustment, which is the harshest and most realistic test mode since it does not compensatefor any type of degradation during the test.

Fig. 6 shows the preliminary test results.

The power cycling results for the benchmark modules are well within the expected curve (blue line) for single-sided sintered modules in the rangeof 60 kcycles.

The results for the SKiN power module by far exceed the target curve (red line), which is already 20 times higher than the industrial standard (green line). The modules passed more than 700k cycles until failure.

In addition, short power cycles with a ΔTj of 70K (80°C to 150°C) werestarted.Here the modules have already passed 3 million cycles. Tests will be continued to EOL. The preliminary results demonstrate the unprecedented reliability of the new doublesided sintered power module. The target was exceeded,resulting in a 70-fold improvement in performance over the industrial standard and a ten-fold improvement over the single sided sintered benchmark module.

It is important to mention that these results are from standard 600V IGBTs with a chip thickness of only 70µm and a standard aluminum top side metallization. Only an additional thin noble metal surface finish is required. The SKiN packaging technology does not require any major changes in chip metalli-zation materials or layer thickness.

Conclusion SKiN Technology is a new packaging technology without bond wires, solder layers and thermal paste. All interconnections to chip top and bottom surface, DBC to heat sink

and power terminals are made using Ag sinter joints.The bond wires have been replaced by a special flex foil which increases the chip surface contact area by a factorof four.

In order to demonstrate the exceptional performance improvements of the overall system and in par-ticular the flex foil, a comparison with a benchmark module featuring conventional Al bond wires was performed.

Thanks to the elimination of thermal interface materials and the integration of a high-performance pin fin heat sink, it is possible to double the power dissipation in comparison to conventional designs. The elimination of the thermal paste layer alone leads up to a 30 percent improvement in the total thermal resistance junction to water.

Owing to the modified geometry and increased chip contact area, a 27percent increase in diode surge forward current capability hasbeen achieved.

The power cycling performance demonstrates an unprecedented 70-fold improvementover the indus-trial standard and a 10-fold improvement over the singlesided sintered benchmark module.

Further activities are underway in order to exploit the new possibilities of the duallayer flex foil. These are, in particular, a further improvement in thermal resistance resulting fromdouble-sided cooling and the integration of passive and active components for gate drive, current and temperature sensing.

Reference:

T. Stockmeier, P. Beckedahl, C. Göbl,T. Malzer: SKiN: Double side sintering technology for new pack-ages, ISPSD 2011

P. Beckedahl, M. Hermann, M. Kind, M. Knebel, J. Nascimento, A. Wintrich: Performance comparison of traditional packaging technologies to a novel bond wire less all sintered power module, PCIM 2011

nnn

Figure 6 Preliminary power cycling results

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Hydraulic System Maintenance Basics – Selecting Quality Hydraulic Lubricants Mobil Industrial Lubricants - ExxonMobil Lubricants & Petroleum Specialties Company

For maintenance professionals, selecting the right hydraulic lubricant is critical to maximizing the service life of their equipment. And, with the range of products available in the market, this is not an easy decision.

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owever, unlike the lubricant marketplace for automobiles and commercial vehicles, for which the American Petroleum Institute (API) serves as the dedicated authoritative industry advisory group setting product quality and performance standards, there is no centralized, standard-setting organization that oversees and sets standards for hydraulic lubricants.

So how can customers make sure that they are purchasing a quality lubricant that will help protect their expensive and critical equipment? Below are several key tips on various hydraulic systems and hydraulic lubricants that can help any plant manager, 94

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maintenance professional or purchasing agent, make an informed decision in selecting the best hydraulic oil for their operation.

What Specifications Should You Look For? The key attributes that one should look for in a hydraulic lubricant are: viscosity, protection against component wear and corrosion, seal compatibility, deposit control, water separability, oxidative stability, and air release.

The starting point for selecting a hydraulic lubricant is the original equipment manufacturers (OEM’s) recommendation.

This may be specific to the machine manufacturer or the pump manufacturer, e.g., Eaton, Denison and Bosch. The OEM’s recommendation should provide the appropriate viscosity grade and indicate a minimum level of anti-wear protection required, such as having Denison HF-O, Vickers M-2950-S and I-286-S approval.

However, OEM suggested guidelines may not always provide detailed recommendations if systems are subjected to extreme working conditions, such as a wide swing in ambient temperatures. In such cases, field application advice from your lubricant supplier can be valuable in helping you make the right choice.

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For example - any equipment that is used outside and subjected to both hot and cold extremes, a synthetic or multigrade lubricant may be the ideal choice because of the ability of these types of lubricants to handle a wider range of ambient temperatures. It is best to consult the OEM directly to confirm maintenance and lubrication suggestions for equipment exposed to harsh conditions.

Some lubricant suppliers tout the oxidation levels of their oils as measured

by TOST (Turbine Oil Stability Test), and state that TOST values is the key component in assessing the performance and life expectancy of hydraulic fluids.

TOST, which is assigned the ASTM test method number of D943, is a glassware test that is primarily designed to characterize the oxidation stability of inhibited steamturbine oils in the presence of oxygen, water, copper and iron metal catalysts at an elevated temperature, -- i.e., the degradation mechanisms associated with steam turbine lubricants.

While oxidation stability is one factor consider, it should not be viewed as the sole criterion. In fact, experts say that more than 75 percent of hydraulic system failures are the result of fluid contamination from dirt, water, or abrasive particles, and not poor oxidation stability.

TOST is, no doubt, a valuable test for determining the quality and performance of turbine oils, for which poor oxidation stability can be a cause of system problems. However, TOST does not provide a complete picture of how a hydraulic lubricant will perform in real life.

Today’s Smaller, HighPressure Hydraulic Systems With new, high-pressure hydraulic systems, contamination can be a costly issue.

Advances in technology, system design and the need to improve productivity have led to smaller-sized hydraulic systems.

Today’s systems feature reservoir tanks that are typically 60 to 80 percent smaller than those of older systems, with higher operating pressures to accommodate precision hydraulic valves. These conditions place added performance requirements on modern hydraulic fluids.

With a smaller fluid volume to dilute

contaminants and tighter internal clearances in hydraulic valves, even a small amount of dirt can quickly damage the equipment. As such, having a “quality lubricant” is not only important for protecting all equipment, it is also especially important for new hydraulic systems.

Proper Maintenance - Maintaining Your Hydraulic System Lubricant Can Help You Save Money on Repairs and Downtime It is essential to keep hydraulic systems clean. To keep contamination out of the system, start by storing and handling oil properly. Optimally, hydraulic lubricants should be stored in a closed container, in a controlled temperature environment with adequate spill containment. Transferring hydraulic lubricants should be done through the use of a filter cart and with the help ofdedicated, sealed clean oil dispensing equipment.

Finally, the hydraulic system reservoir should have a quality desiccant breather and system filter, as recommended in the manufacturer’s guidelines.Some systems utilize auxiliary filtration systems, e.g., kidney loop, that continually “polish” the hydraulic fluid to maintain system cleanliness.

As part of routine maintenance, one should be rigorous in checking the “health” of the hydraulic oil and the hydraulic system itself. It is advisable for maintenance professionals to perform quarterly oil analyses and annual system inspections. For systems that are most critical to a plant’s operation or are subjected to challenging conditions, a monthly oil analysis should be considered.

The oil analysis should include a measurement of fluid viscosity, water content, particle count and dissolved metals to determine how well the system is operating.

Examining changes in the oil analyses over time, also known as “trending”, is necessary to assess the condition of the hydraulic fluid.

By trending oil analysis data it is possible to take proactively address undesirable conditions before they become problems.

System inspections should be done to check and document the condition of the plant hydraulic systems. System Inspection

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data can be used to establish the optimum time to perform maintenance on critical hydraulic components such as filters, breathers, valves, hoses, heat exchangers and pumps. Comprehensive leak detection should be performed if excessive hydraulic oil usage is detected during a routine system inspection.

Ask for Proof Plant m an agers, m ainten ance professionals and purchasing need to select the right hydraulic lubricant to maximize the service life of their equipment.

Select hydraulic oil based on sound technical information that represents properties relevant to hydraulic oils. Ask your supplier for customer references and evidence beyond lab glassware tests that indicate their products really perform in service as their brochures and advertising suggest.

To minimize chances of hydraulic failures, one should be aware of the various conditions under which the equipment will be exposed and the key performance characteristics that a lubricant should have. In order to maximize hydraulic system performance, one should always be sure to perform routine oil analysis and system inspections to maintain a clean system.

Following these simple tips can help save time and money, and make the process of maintaining hydraulic systems and buying hydraulic lubricants easier. nnn

What is TOST? “This test method [TOST Turbine Oil Stability Test] is widely used for specification purposes and is considered of value in estimating the oxidation stability of lubricants, especially those that are prone to water contamination. It should be recognized, however, that correlation between results of this method and the oxidation stability of a lubricant in field service may vary markedly with field service conditions and with various lubricants.” From Section 4 "Significance and Use" of ASTM Standard Test Method D943

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Modelling Smart Grid Communications Vikram Kataria Director Business Development Ericsson India Pvt Ltd

Around the world electricity utilities are updating and re-architecting their power networks. This is largely in response to growth in user demand and the restructuring of generation (including distributed supply from renewable generation such as wind and solar). However, there is also a compelling need to re-think existing architectures to incorporate far more pervasive communications.

The resulting “smart grid” is a synthesis of energy, IT and communications infrastructures.

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ome power engineers may argue that communications has been part of utility networks for decades. This is true. SCADA networks have been monitoring power transmission lines and equipment in substations since the 1950s. Utilities have been controlling user demand through tone control of off-peak hot water heaters and pool pumps since the 1960s and possibly earlier.

H oweve r, t h e s e a r e m o d e s t communications components incorporated into a power network architecture that has changed little since the basic model was introduced by Edison and Tesla in the 1880s.

And it is still the case that the great bulk of utility distribution infrastructure (located in streets and on poles) is almost entirely offline – such that utilities often have no way of detecting faults other than waiting for their customers to call and complain.

Today, energy utilities are testing, piloting, or rolling out the building blocks of their smart grids. In a smart grid the key enabler is the communications infrastructure that overlays and intertwines with the power distribution infrastructure. It works in conjunction with field devices and office applications to monitor and manage power distribution infrastructure, making automatic adjustments as real world events such as storms, fires and runaway trucks damage the integrity of the physical grid.

The benefits for consumer and business users will be a more robust supply of energy with reduced carbon emissions and tools to help users reduce their own carbon footprint.

This discussion of smart grid goes beyond the deployment of smart meters (also called advanced metering infrastructure or AMI). The introduction of smart meters has predominantly been focused on the 96

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introduction of ‘time-of-use’ tariffs and inhome displays, with the expectation that consumers will modify their behaviour to consume energy at times of lower demand.

While the concept of smart grid incorporates the introduction of smart meters, it is more far-reaching in that it directly helps utilities better manage their power networks.

have to be quickly identified and appropriate devices commanded to fix or minimize the consequences of the problem. This is often referred to as FDIR (fault detection, isolation and recovery). Traffic volume requirements are expected to be small, but commands and responses must be dealt with quickly and with high priority.

The challenge to engineers when implementing a smart grid is to understand the dynamics of monitoring and managing the power network and to map this into communications traffic requirements (throughput, latency, etc.), to ensure that the communications infrastructure can be scaled and deployed to meet realistic future requirements.

The volume and nature of communications regarding FDIR will be determined by the extent to which detection and recovery are dealt with centrally or through local distributed mechanisms, or a combination of central and distributed control mechanisms.

As a provider of sm ar t-grid communications networks, Ericsson has a keen interest in facilitating a detailed understanding of this subject and is collaborating in a program of research to model these requirements and validate the models against real power networks. This modelling is expected to cover the following range of scenarios or use cases.

Grid Monitoring and Control Just as SCADA networks have been used to monitor and control the transmission and substation portion of power networks for many years, smart grid aims to extend the monitoring into the distribution network.

Examples of devices to be monitored include transformers, fault detectors, poletop switches, sectionalisers and reclosers.

Communications traffic requirements are expected to be modest, but status reporting will be frequent.

When monitoring identifies grid failures, the root cause of the failure will

The introduction of grid monitoring and control is expected to greatly reduce the frequency and impact of faults in the distribution networks. This will lead to improved reliability figures for the utility.

Pervasive communications will also enable the introduction of new regimes for using and maintaining grid equipment. Dynamic rating allows switching and dispatch decisions to be based on the actual condition of equipment due to their operating environment and operating history rather than their factory specifications. Condition-based maintenance allows grid equipment to be serviced according to actual load history and condition rather than on fixed schedules. This avoids the costs of too-early servicing and prolongs asset life by avoiding too-late servicing.

Advanced Metering Infrastructure Where smart meters are introduced the assumption is that they will be read frequently (even several times a day). Smart meter traffic volumes are expected to be small and infrequent for each meter, but substantial in aggregate across the thousands of meters to be read. While each read may

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have a low priority, the records are of high importance to the utility as they are the basis for charging customers.

somewhat distributed throughout the grid (albeit likely to be centralised in certain areas such as business districts).

resolution times. This is an unusual smart grid use case in that it requires mobile telecommunications.

Demand management of in-home devices is likely to be done through the meter. This may be regular (e.g. turn-on/ turn-off hot water systems based on time of day), or for emergencies (e.g. fine-grained disabling of particular devices such as pool pumps or airconditioners) in emergencies or for supply shortages. Traffic volumes are expected to be small and infrequent but substantial in total.

More challenging is the introduction of autonomous distributed generation throughout the grid (small-scale solar/ photovoltaic, small scale gas turbine or fuel cells), which requires the re-thinking of the distribution network into a bidirectional grid, along with the increased desirability of using embedded storage to smooth supply. Smart meters will typically be used to record energy generated, and this must then be read for cross-charging and billing settlements where incentive tariffs are in place.

There will also be a need to implement communications gateways such that field staff can easily communicate with corporate/ office-based staff, and in some cases with other field teams (e.g. emergency services workers) who may be using quite different wireless technologies.

Service connection/disconnection (i.e. disabling or enabling energy supply to a premise) offers significant benefits. Perhaps the most obvious is being able to deal with a change in ownership of a property. There are also benefits when dealing with disaster recovery, such as the gradual ramping up of supply on the distribution grid after a major failure (this was an issue dealt with recently in Queensland in dealing with the aftermath of Cyclone Yasi and the statewide floods that occurred there). Traffic volumes are very low, but of relatively high priority.

Perhaps the most challenging “use case” regarding smart meter communications is the remote over-the-air (OTA) updating of the meter firmware. In worst-case scenarios this could apply to all meters in a region and may have to be done over a relatively short period (e.g. a day).

While some calculations of this use case suggest it can be a very challenging task, with thousands of meters having to receive megabytes of data, these calculations tend to ignore techniques that allow efficient use of the communications infrastructure (e.g. the use of multicast).

Distributed Energy Resources While large sources of renewable supply (windfarms, solar, geothermal, wave/tidal) are increasing in number, they do not of themselves change the topography of the power grid, other than by requiring new transmission capacity to allow connection.

However the irregular nature of their supply may lead to the introduction of new elements within the grid, notably distributed storage (e.g. flow batteries). And these elements will themselves have to be monitored and managed.

Co-generation or tri-generation, where business owners generate electricity (typically from gas), introduces another new source of supply, which is somewhat predictable, and

Distributed energy resources will be an increasingly important aspect of the smart grid. It will introduce new devices and processes for monitoring and managing the grid. Current understanding suggests that these changes, while challenging for the power grid, will only drive modest communications requirements… but the area is new and much remains to be learnt.

Electric Vehicles The introduction of electric vehicles must drive a re-architecting of the grid and not just because of the massive increase in nighttime demand that seems likely. What other element on the grid is simultaneously a load, embedded storage, distributed generator, and roams from place to place throughout the day?

The mobility of electric vehicles introduces a need to handle the authentication of devices, prior to the transfer of energy to or from the vehicle. A thoroughly novel concept for the grid, which was designed for supplying energy to premises that stay put.

It is difficult today to be confident of the communications requirements for a smart grid with a large population of electric vehicles as the business models supporting them are still being tested. However, early work suggests that the changes in IT systems and energy infrastructure will overshadow the communications requirements.

Field Staff Then there is the need to interact with field staff as they go about changing, maintaining and repairing the grid. In addition to field-force automation which supports the optimized scheduling and dispatch of crews, the ability to communicate real-time grid status and outage information to field staff will significantly improve fault-

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During normal operations communications requirements are expected to be relatively modest, though traffic could be more substantial when crews are in a section handling a major event.

Conclusion As discussed, there are a wide variety of requirements for smart grid communications, from regular low priority traffic to missioncritical disaster handling traffic.

Utilities have considerable experience with the communications requirements for the real-time monitoring and managing of the high-voltage transmission portion of the grid, moderate experience with the mediumvoltage portion, and least experience with the low-voltage distribution network.

Understanding how the combined grid, communications, and IT systems will interact requires sophisticated modelling, and the testing of the results of modeling by validation against real smart grids as they are deployed.

What is already clear is that it is essential that utilities design for the future.

A communications network that is designed merely to handle meter reading cannot deal with the complexities of a smart grid with distributed generation and electric vehicles.

The introduction of smart grid is not a simple bolt-on to the existing power grid. Smart grid enables very different and very efficient processes that will increase the reliability of the grid, optimise demand, and reduce the carbon emissions and operating costs of the grid.

To achieve these important benefits will require investment in communications infrastructure, smarter grid equipment, and new people and IT processes.

However, to make it possible for utilities to introduce future-proof communications for their smart grids, it may be necessary in many jurisdictions to change the legislated basis for access to the capital to fund this infrastructure, so that utilities really can build for the future. nnn EQ INTERNATIONAL November/December 11

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Smart Metering - The First Wave Of Smart Grid Adoption In India Navodit Kumar Garg, Dy Director, Head for Vertical Solutions, Huawei Enterprise

Advanced Metering Infrastructure (AMI) and Automated Meter Reading (AMR) is laying a very solid foundation for the first wave of Smart Grid adoption in India If we take a look at the Indian power sector, one of the biggest challenges for them today comes from the power distribution arena as economical variability and sustainability of power distribution operations is a big issue. This is primarily because of High AT & C Loses (Varies from 10 % to as high as 55%), poor network infrastructure, Power Deficit, Power reliability and so on…

Smart Metering coupled with India-specific customization can help utilities to address most of these challenges.

Indian Scenario Today’s power grid is overburdened, and in order to increase on its reliability, and commercial sustainability, there is a transition towards smart grid happening at various levels. As a result, there is a need to keep pace with modern technological advancements and incorporate smart metering capabilities in order to maintain sustainability and move another step towards smart grid. Every year in India alone, losses are estimated in the range of billions of dollars. The beauty of the 98

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smart meter strategy is that it eliminates contact between the customer and a Field Staff, which is often a factor in collusion.

In many cases, and in an approach, highuse customers are targeted first. Customers using a lot of energy also generally will stop stealing it once they realize the utility has the tools to detect and record the theft.

“Combating theft is certainly not the only driver for this initiative, but is the primary reason for early smart meter deployments in selected urban areas

It is interesting to note that in the past, the only way to address this issue was to expand the grid capacity and build more power plants, which eventually increased electricity costs. However, on the other hand, today, apart from other Smart grid technologies, AMI and AMR techniques are leading the way out for handling such issues with technological prowess.

Driving Factors Smart grid will be driven by the expected outcomes and their practicality for Indian scenario; most of the targeted benefits have become urgent requirement in India, especially after looking at the Economical

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lie in substituting fossil energy with renewable energy, creating an i n n ov a t i ve e n e r g y consumption system, thoroughly reconstructing the existing energy consumption system t h r o u g h I T, a n d maximizing the energy efficiency of power systems.

Growth rate targets for the power sector.

AMI and AMR address the last leg of distribution value chain and becomes the first step to be taken because it addresses majority of challenges and have been proven the most effective initiative across the globe. Indian government has shown its seriousness with the setting up of Smart Grid task force for ensuring the smart grid initiative should go in strategic and planned manner. Smart grid task force will be key driver for enabling the technologies and their implementation with clear short term and long term objectives.

In today’s scenario many countries are focusing on energy conversation, green energy, and sustained growth. The most challenging tasks for energy development

Grid’

Huawei’s Round-theClock ‘Smart

Ideally a smart grid is designed to connect electric equipment - from energy development to utilization - and other energy consumption facilities through a digitalized information network, that enables accurate, appropriate, and mutually-aided energy supply through smart control and maximize the balance between cost and return on investment.

The smart grid has eight features – it is self-healing, interactive, strong, of high quality, compatible, economical, optimized, and an integrated grid. Because of these features, the smart grid has remarkable advantages including an early-warning control system and preventive control and self-diagnostics, fault isolation, and self-recovery; improvement of utilization and reduction of CapEx and OpEx; highly integrated and shared grid information; a unified platform and model, and standardized and refined management.

The Huawei Smart Grid solution features E2E communication - from the access of substations a n d p ow e r p l a n t s through transmission and distribution bearing, to distribution automation and AMI. The communication network in the smart grid is larger than that in the traditional grid. This poses difficulties in operation and maintenance (O&M).

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Huawei provides convenient O&M to all customers in the power industry by leveraging its experience in large-scale network O&M. Huawei Smart Grid solution supports unified network management, reduces O&M difficulty and cost, and improves the efficiency of engineering implementation.

The Huawei Smart Grid solution comprises three sub-solutions, Wide Area Network (T&D), ADO, and AMI. Huawei provides the IP and basic transport network in the Wide Area Network (T&D) solution to build a basic network that is highly reliable and secure. In addition to providing industry-leading communication products and solutions, Huawei can also provide E2E network planning, design, implementation, and managed services. Huawei can provide round-the-clock services for customers through its global service network. nnn

Navodit Kum ar Garg, Dy Director, is head for the Vertical Solutions Market in Huawei Enterprise Group. He is responsible for the technical sales in industry verticals like BFSI, Energy, Power and Govt. His key role has been to understand the customer needs, pain points and leveraging the current technologies, solutions to help customers grow their business smartly and efficiently.

A gold medalist and graduated in B.Tech Electronics & Comm unications from GNDU , Punjab and also holds Management degree.

He has rich experience of 16 years in the telecom industry; served in Major Telcos like VSNL, TCL and Reliance Infocom. Prior to Huawei he was in Nortel, responsible for solution sales on CEN and Optical Networks.

In Huawei he has been key architect of many solutions for Teleco and utility companies across India and globally.

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PRODUCTS What does Un = 1000 V d.c. mean for the boxes?

When using electrical components in the range of photovoltaics there is the result of off-load voltage up to Uoc = 1000 V caused by series connections of several pv modules. Those pv modules work with direct current (d.c.).

The above mentioned facts have to be regarded when choosing components for the generator-junction- boxes as well as for active parts, i.e. surge protection devices or disconnector and for the used boxes.

The normative background for the installation of photovoltaic plants is the IEC 60 364-7-712.

In this document the statement is issued that protection class II (insulation) should be used as protection measure.

Protection class I (protective earthing) cannot be used because in case of fault the protection measure would not work caused by the insufficient short-circuit current (Ik ≈ 1,1 x In). The nominal current In depends i.e. on the solar radiation on the pv module.

Caused by high voltage up to 1000 V the protection class III do not work either (protection low voltage up to 120 V d.c.). => Therefore boxes made from insulating material are a good choice (i.e. HENSEL Mi-Boxes).

For the production of generator junction boxes the IEC 61439 has to be obtained.

In this document the test conditions are regulated.

Part 10.9.4 issues the statement that concerning boxes from insulating material the multiplier 1,5 has to be used relating to “table 8”.

“Table 8” shows which insulation-testvoltage at which voltage (Ui) has to be used, i.e. for 1000 V d.c. is classified: test voltage Ui = 3110 V x 1,5 => 4665 V for 1500 V d.c. is classified: test voltage Ui = 3820 V x 1,5 => 5730 V The HENSEL KV-, ENYSTAR- and Midistributors have passed the insulation test in the Hensel quality assurance with 4665 V. Therefore this distributors are suitable for the operation of Uoc = 1000 V.

Solar Pump Controller MPPT To make Solar Power a viable proposition in India, we have to overcome the barriers of high PV panel and battery costs. Though we have seen considerable drop in PV prices which will slide further in the coming years, the battery costs and life of around 3 years hinder the use of solar power, especially in the rural areas.

This new product, a Solar Pump Controller MPPT works without the need of a battery and can pump water from around 6am to 8pm all throughout the day. In early mornings and late evenings, when panel voltage drops considerably, this controller still ensures that the pump works, although pumping less water. In this manner, the solar photovoltaic panel is maximized for this application, using whatever power that is extracting from the panel. Without the need of a battery, the cost of this system reduces drastically and this system now becomes affordable to farmers who cannot rely on a consistent power source.

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A standard solar charge controller cannot be used for this purpose due to many reasons and has to be customized for this application.

Most Solar Pumps have an intrinsic problem that they would operate only for a few hours in a day when the voltage of panel is high.

Through months of testing and tweaking, KB Electronics, Mumbai proved this product in Nagpur, where it is operating for 14 hours a day and now there are installations all over India. The pumps can be of .5HP, 1Hp, 1.5HP, 2HP onwards. The Solar Pump controller can be from 125W to 10kW.

KB Electronics, a Power Electronics Manufacturing company in Mumbai, has entered the renewable energy sector after 25 years in the Power industry with products such as Solar Charge Controller MPPT, Solar Charge Controllers On/Off, Wind Charge Controller and Grid Battery Chargers with 3 stage charging. They also make Switch Mode Power Supplies (SMPS) and DC-DC Converters. With a focus towards designing for Indian conditions, KB’s products are built to withstand the extreme conditions found in India such as input surges, moisture and dust. To know more, you could visit www. kbelectronics.co.in .They also arrange free demonstrations of their products.

India’s growth story will be catalyzed by such products targeted to critical product categories such as water and energy, to help bring about change and independence to the people in all locations however remote.

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PRODUCTS TOOLFOX – Right Tools For Photovoltaic Applications The key feature of a professional tool is that you enjoy working with it! The excellent feel and ergonomics of the design, a long service life, and functionality guarantee optimum efficiency and quality. These properties are perfectly combined in all tools from Phoenix Contact.

ensure long-term stable cutting performance and therefore a clean cut, for both soft and hard wires (piano wire).

generation of crimping pliers. A new power transmission method reduces the amount of manual force required by 25% at maximum crimping pressure.

The handles’ excellent geometry also makes for light work. The integrated pressure lock ensures long-term stability as well as high quality, gas-tight crimping.

CRIMPFOX -SR 6… crimping pliers are used to process MC3 and MC4 solar connectors from Multi-Contact and SOLARLOK connectors. The integrated locator ensures easy processing with optimum crimping results.

WIREFOX – Insulation stripping tools The WIREFOX product range provides the perfect tool for every stripping task.

WIREFOX precision stripping tools from Phoenix Contact make a real impression thanks to their excellent ergonomics and the special geometry of the hardened blades.

SCREWFOX – Screwdriver CUTFOX – Wire/Cable cutting tools With CUTFOX, Phoenix Contact offers the perfect cable cutter for every application.

Various designs are available for processing different cable diameters. All parts of the cable cutters that are under particular strain are tempered or especially hardened.

Thanks to their special cutting geometry, the front cable cutters ensure optimum cutting results over the entire cross-section range up to a diameter of 35 mm (300 mm2).

The WIREFOX -D 11 stripping tool strips single and multi-wire signal, control, and glass fiber cables up to 11 mm in diameter. Easy handling is combined with precise results.

The WIREFOX -D SR 6 stripping tool is specifically designed for solar cables.

The ergonomic design of the handles makes for light work.

CRIMPFOX – perfect crimping pliers

The VDE-insulated diagonal cutters with their inductive hardened precision cutting

The extensive CRIMPFOX product range offers the professional user a new

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The complete Range of Accurately dimensioned VDE approved screwdrivers are available for every screw size.

Screwdriver blades from Phoenix Contact have a large bearing surface in the screw head to achieve the required torque with adequate force without damaging the screw head.

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Th i r d edi t i on of India’s p r emier s olar e v e n t - S O L A RC O N I ndia 2011 concludes s uc c e ssful l y SOLARCON India will be back next year September 3-5, in Bangalore

S

OLARCON India 2011, the third edition of India’s premier solar industry event, was inaugurated by Francisco J. Sanchez, Undersecretary for Commerce for International Trade, USA concluded successfully on 11 November 2011. SEMI India, the premier solar PV industry trade body and organizer of SOLARCON India said that it has received an overwhelming response from the industry and stakeholders to this year’s conference on the theme “Charting India’s Roadmap to Solar Leadership - Translating Potential into Reality” as well as the exhibition. SEMI will build on this year’s success and plans an expanded SOLARCON India 2012 to be conducted September 3-5, in Bangalore.

SOLARCON India 2011 focused on technology trends, business opportunities, work force development, technology tie ups and best practices that will drive and influence the growth of the Indian solar PV industry. It also provided insights into the realities and challenges faced on the ground by developers building solar photovoltaic (PV) projects in India.

The exposition, held alongside the main event and reflecting the widening solar value chain in India was themed “Showcasing the Solar Eco-System: From Polysilicon to Power Plants”. There were as many as 116 exhibitors from across the entire solar value chain. There were 36 companies either directly or indirectly involved in EPC

102 EQ INTERNATIONAL November/December 11

activities clearly indicating the growth of the industry under the JNNSM and other state programs.

entrants in the solar space like L&T, JFlex, Arkema, Progetti used the event to launch their India operations.

This year’s exhibition witnessed high quality business visitors with a substantial number from among senior CXO level professionals and Board level executives.

Despite the fact the conditions in the host city was not at its usual best, the show had witnessed substantial visitor’s footfall. The conference saw over 400 delegates from various countries, across manufacturing, technology, materials, EPC, plant developer and component manufacturing segments actively discussing trends, opportunities and challenges of the Indian solar industry.

Speaking on the success of SOLARCON India 2011, Debasish Paul Choudhury, President, SEMI India said,“The third edition exceeded our expectations and am pleased with the response from all stakeholders to SOLARCON India 2011. The encouraging response provides us the confidence to work more closely with the Indian industry and the Government towards the growth of the sector. I am personally excited about the role we can play in the Indian solar / PV market which is on a sharp growth curve.”

The dual-track conference featured 70 high profile speakers including Dr. Angelo Mascarenhas, US-NREL, Dr. Anjaneyulu Krothapalli, CEO, Sujana Energy, Dr. Bharat Bhargava, Director - PV, Ministry of New and Renewable Energy (MNRE), Govt. of India, Craig O’Connor, US Exim Bank, Hari Ponnekanti, Applied Materials, Jim Brown, President, First Solar, Dr. Josef J. Haase, CEO Cell & Module, Centrotherm PV, K. N. Subramaniam, CEO Moser Baer Solar Systems, K.S. Popli, Director – Technical, IREDA, Peter Ballinger of OPIC, and Sudhansh Pant, IAS, Jaipur & Ajmer Vidyut Vitran Nigam, among many others.

SOLARCON India 2011 was certified by the US Department of Commerce, and a US pavilion consisting of 14 companies was a special feature of the exposition. The event was supported by MNRE, IREDA and APIIC, drew several Indian and foreign solar manufacturers to the exhibition. New

In response to the experience, Vish Palekar, CEO and Business Head, Cleantech Ventures, Mahindra Partners commented; “Mahindra Solar and Mahindra World City, Jaipur participated jointly in the event. Like last year, this event was very well received having quality footfalls from vendors and clients. With the Phase 1B of JNNSM bids on the verge of being released, this event comes at the most appropriate time where the EPC companies, manufacturers and developers could come together. SOLARCON India has once again proved to be an important platform for the industry to meet and shape its growth”.

A three day training programme on “Grid Connected Solar PV Power System” organized along with the National Centre for PV Research and Education was also part of the event. Nearly 70 attendees drawn from the industry, academia and consulting firms participated.

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CONFERENCE & EVENTS Inter Solar India Date: 14-16 Dec, 2011 Place: Mumbai Organiser: MMI India Pvt Ltd, Solar Promotion

International, Freiburg Management and Marketing International GmbH (FMMI) Tel.: +91 22 4255-4707, +49 7231 58598-0 Email: info@intersolar.in Web.: www.intersolar.in

Elecrama 2012 Date: 18-22 Jan, 2012 Place: Mumbai Organiser: IEEMA Tel.: 22-2493 0532 / 6528 Email: rajeev.ketkar@ieema.org Web.: http://www.elecrama.com/Elecrama2012/

Index.aspx

IPTEX 2012

5th North American offshore Wind Summit 2012

Date: 15-17 Dec, 2011 Place: Coimbatore Organiser: PSG College of Technology, Tel.: 422 2572177 Email: psgret2011@gmail.com Web.: www.psgtech.edu/icoret11/Home.html

Date: 23-26 Jan, 2012 Place: Washington Organiser: Information Forecast Inc. Tel.: 818.888.4444 Email: mail@infocastinc.com Web.: informationforecastnet.com/index.php/

The Carbon Congress 2011

2nd Inverter and PV System Technology Forum

Date: 09-11 Feb, 2012 Place: Mumbai Organiser: Virgo Communications & Exhibitions Tel.: 080 - 2556 7028 Email: info@virgo-comm.com Web.: www.ipte.virgo-comm.com/2012/index.html

conference/offshore12

Date: 23-24 Jan, 2012 Place: Berlin Organiser: Solar Praxis Tel.: 49 (30) 72 62 96-304 Email: miriam.hegner@solarpraxis.de Web.: www.solarpraxis.de/en/conferences/2nd-

inverter-and-pv-system-technology/general-information/

ICREU 2012 Date: 04-06 Jan, 2012 Place: Coimbatore Organiser: CITI Tel.: 9629283060 Email: secretary@icreu2012.com Web.: www.icreu2012.com/

World Future Energy Submmit 2012 Date: 16-19 Jan, 2012 Place: Abu Dhabi Organiser: Reed Exhibitions Middle East Tel.: 971 2 409 0409 Email: claude.talj@reedexpo.ae Web.: http://www.worldfutureenergysummit.com

104 EQ INTERNATIONAL November/December 11

Date: 08-11 Feb, 2012 Place: Mumbai Organiser: Chemtech Tel.: 22-40373737 Email: sales@jasubhai.com Web.: www.chemtech-online.com/events/enertech/

index.html

iCORET 2011

Date: 19-20 Dec, 2011 Place: New Delhi Organiser: CINBM Tel.: 80507 61469 Email: kamal@cinbcorp.com Web.: www.cinbcorp.com/carboncongress.html

Enertech World Expo 2012

PV Korea 2012 Date: 15-17 Feb, 2012 Place: Korea Organiser: INFOTHE Co., Ltd. Tel.: 82 2 718 6931 Email: interexpo@infothe.com Web.: http://www.exposolar.org/2012/

Solar Power Generation USA Date: 31 Jan- 2 Feb, 2012 Place: United States Organiser: Green Power Conference Tel.: 44 (0)20 7099 0600 Email: sales@greenpowerconferences.com Web.:

Clean Energy Expo Date: 23-25 Feb, 2012 Place: Beijing Organiser: Koelnmesse Co Tel.: 86 10 6590 7766 Email: h.chen@koelnmesse.cn Web.: www.cleanenergyexpochina.com/

3rd Wind Conference and Exhibition (WE20 by 2020)

The Solar Future India - II

Date: 05-07 Feb, 2012 Place: Coimbatore Organiser: Indian Wind Power Association Tel.: 98404-00024 Email: secretary.general@windpro.org Web.: http://www.windpro.org/index.htm

Date: 29 Feb -1 Mar, 2012 Place: Jaipur Organiser: Solar Plaza Tel.: 31 10 280 9198 Email: m.munro@solarplaza.com Web.: http://www.thesolarfuture.in/

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CONFERENCE & EVENTS Solar Expo

PV Expo 2012 Date: 29 Feb -2 Mar, 2012 Place: Tokyo Organiser: Reed Exhibitions Japan Ltd Tel.: 81-3-3349-8576 Email: pv@reedexpo.co.jp Web.: http://www.pvexpo.jp/en/

PV America 2012 Date: 19-21 Mar, 2012 Place: San Jose,CA Organiser: Solar Energy Industry Association Tel.: 202-595-1144 Email: lcohen@solarenergytradeshows.com Web.: http://www.pvamericaexpo.com/index.html

Solarcon China 2012 Date: 20-22 Mar, 2012 Place: Shanghai Organiser: Semi Tel.: 86 21 5027 0909 Email: exie@semi.org Web.: http://www.semi.org.cn/solarconchina/en/

7th Asia Solar PV Industry Exinbition 2012 Date: 21-23 Mar, 2012 Place: Shanghai Organiser: Shanghai AiExpo Exhibition Services

Co., Ltd Tel.: 86-21-65929965 36411666 Email: info@aiexpo.com.cn Web.: http://www.asiasolar.cc/en/index.asp

Wind Power 2012 Date: 27-28 Mar, 2012 Place: Johannesburg Organiser: Terrapinn Tel.: 27 (0) 11 463 6001 Email: enquiry.za@terrapinn.com Web.: www.terrapinn.com/exhibition/wind-power-

africa/index.stm

International Green Energy Expo Korea Date: 28-30 Mar, 2012 Place: Korea Organiser: EXCO, Korea Energy News Tel.: 82-53-601-5371 Email: energy@excodaegu.co.kr Web.: www.energyexpo.co.kr/eng/

EWEA 2012 Date: 16-19 April, 2012 Place: Denmark Organiser: EWEA Tel.: 32 2 213 18 60 Email: events@ewea.org Web.: http://events.ewea.org/annual2012/

Date: 09-11 May, 2012 Place: Italy Organiser: Expoenergie Tel.: 39 0439 84 98 55 Email: brouxp@solarexpo.com Web.: www.solarexpo.com/SE/EN/

World Renewable Energy Forum Solar Date: 13-18 May, 2012 Place: Colorado Organiser: American Solar Energy Society Inc Tel.: 720.420.7939 Email: khotchkiss@ases.org Web.: ases.org/index.php?option=com_content&vie

w=article&id=18&Itemid=147

Indian Solar Investment & Technology Summit & Exhibition 2012 Date: 19-20 April, 2012 Place: Ahmedabad Organiser: Solar Media Tel.: 44 20 7871 0123 Email: gnair@solarmedia.co.uk

Power Gen India & Central Asia /Renewable Energy World 2012 Date: 19-21 April, 2012 Place: New Delhi Organiser: PennWell Corporation,Inter Ads Exhibi-

tions Pvt Ltd Tel.: 44 (0)1992 656 610, 91 124 452 4508 Email: avnish-seth@interadsindia.com Web.: http://www.power-genindia.com/index.html

3rd Renewable Energy Technology Congress 2012 Date: 25-27 April, 2012 Place: New Delhi Organiser: Energy And Enviroment Foundation Tel.: 91-11-24538318 Email: punit.nagi@wretc.in Web.: http://www.wretc.in/index.aspx

Genera 2012 Date: 23-25 May, 2012 Place: Madrid Organiser: IFEMA Tel.: 34 91 722 57 22 Email: nuria.ochagavia@ifema.es Web.: www.ifema.es

6th SENEC PV Expo 2012 Date: 16-18 May, 2012 Place: Shanghai Organiser: Follow Me International Exhibition Ltd. Tel.: 86-21-64276991 Email: info@snec.org.cn Web.: http://www.snec.org.cn/lt111e.asp

20th European Biomass Conference & Exibition 2012

Date: 18-22 Jun Place: Italy Organiser: WIP-Renewable Energies ,ETA-Florence

Renewable Energies Tel.: 49 89 720 12 765, 39 055 500 22 80 Email: biomass.conference@wip-munich.de Web.: www.conference-biomass.com/ Welcome.404.0.html

For Listing of your Event : Conference and events are listed free-of-charge, so please feel free to get in touch to tell us about your event. We would also be happy to provide you with free copies of magazine for distribution at your events.(while stock last). Please send your conference information to : Mr. Gourav Garg at gourav.garg@EQmag.net

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