Global Solar Technology - South East Asia issue 1.2

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Southeast Asia

For Solar and PV Manufacturing Professionals

Covering India, Thailand, Malaysia, Singapore, The Philippines and Hong Kong Volume 1 Number 2 Summer 2010

Flexible silver paste enables thin-film photovoltaic flex solar cells

Soni Saran Singh Interview Inside

Advanced screen printable thin film PV silver conductor compositions

NEW PRODUCTS

‘Printing’ PV electrodes onto flexible substrates

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Contents

Southeast Asia

Covering India, Thailand, Malaysia, Singapore, The Philippines and Hong Kong

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Contents 2

Volume 1, Number 2 Summer 2010

Give us more solar shine Debasish P. Choudhury

20

Technology Focus

10 Flexible silver paste enables thin-film photovoltaic flex solar cells

Dr. Hong-Sik Hwang, Lee Kresge, James Slattery and Dr. NingCheng Lee, Indium Corporation 16 Advanced screen printable thin film PV silver conductor compositions

Jay R. Dorfman, DuPont Microcircuit Materials, and Vince Arancio, DuPont (UK) Ltd

26

20 ‘Printing’ PV electrodes onto flexible substrates

Mark David Miller, Extrusion Dies Industries, LLC (EDI) 26 Flexible non-contact laser soldering for solar cell strings Andreas Kriegler, teamtechnik 30 Improving the commercial viability of concentrator lens technology Laurence Hayward, VentureLab Inc.

24

Special Features

24 28 32 39

Interview—Soni Saran Singh­, NMTronics India Pvt. Ltd. PV Standards at SEMI SOLARCON India 2010 Preview PV + Solar India 2010 Review

REGULAR COLUMN

4

Solar Mission all set to take off!

Mr K Subramanya

Regular Features

Today, laser technology is still an expensive soldering method.

Nonetheless, 50% of the stringers teamtechnik builds for customers are equipped for laser soldering.

6 34 38 40

Industry News New Products Association News Events Calendar

Visit the website for more news & content: www.globalsolartechnology.com.

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Global Solar Technology South East Asia – Summer 2010 – 1

Editorial

Trevor Galbraith

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Editor in Chief

Give us more solar shine At the outset, a big ‘Thank You’ to the entire solar industry in South East Asia, and India in particular, for the hearty welcome and also for your invaluable support to our new edition. South East Asia is now a hotbed of the solar energy adoption, manufacturing and research & development activities.

11 January 2010 was a red-letter day for the Indian solar industry. The National Solar Mission, which is part of India’s National Action Plan on Climate Change, was launched by the Prime Minister in New Delhi. Fast forward to 16 June 2010: Dr. Farooq Abdullah, minister for new & renewable energy, announced the guidelines for off-grid and decentralised solar applications and rooftop & other small solar power plants, totalling 300 MW capacities. By the time the magazine reaches you, I have been told, the policy guidelines for the large grid connected solar power plants for the remaining 1,000 MW of the 1,300 MW first phase (2010-13) of the Jawaharlal Nehru National Solar Mission will be announced. No doubt, it’s one of the major policy announcements of the UPA-2 government, and a policy document that will open up flood gates of proposals by the global solar eco-system.

However, there are a few concerns.

Will the mission work as a catalyst in developing the manufacturing ecosystem in the country? Will the new guidelines for large grid connected solar power plants address all the contentious issues raised by the solar farm developers? What would be the criterion for selecting a solar farm developer when bombarded with massive investment proposals? How efficient would be the power evacuation in the absence of a stable and reliable-grid? Availability of a world-class testing facility, common certification standard and manpower issues need to be addressed for rapid PV adoption as well.

Currently, India doesn’t house a single integrated manufacturer of solar products and systems. Some of the local manufacturers announced major expansion plans under the government’s

2 – Global Solar Technology South East Asia – Summer 2010

SIPS program for semiconductor, solar cell and LED manufacturing, but most likely these capacities would be ready in time for the second phase of the JNNSM (2013-17).

I candidly remember the outgoing President Dr. APJ Abdul Kalam’s address to the Parliament Farewell function on 3 July 2007. One of the most significant points of his speech was aiming at achieving Energy Independence by 2030.

Dr. Kalam advocated the use of renewable energy as a key component to achieve the coveted energy security. I was inspired by this thought when I incubated India’s first international solar trade show in 2007 titled Solar Tech India, which was later rechristened to Renewable Energy India in 2008. A plethora of trade shows have sprung up over the entire country. Since January, I have attended three maiden trade shows, am now preparing for the fourth one later this month, and will be attending a couple of trade shows by Christmas. Personally, I would like more platforms to emerge so that greater public awareness about the virtues of the solar electricity is spread across the knock and corner of the country.

For centuries, Sun has been worshipped as the ultimate source of energy in India. Today, there is a real opportunity for the humankind to transform this legend to business.

—Debasish P. Choudhury Editor Global Solar Technology South East Asia

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Title

Solar Mission all set to take off!

Mr K Subramanya CEO, Tata BP Solar

Solar Mission all set to take off!

The Indian solar industry is all set to take off, as it has been for the last two years when the National Solar Mission was first announced. Hopefully the final policy guidelines and the notification to receive Expressions of Interest for the MW-scale projects under the Phase 1 of the Jawaharlal Nehru National Solar Mission will be issued soon. This will open the gates for the first batch of 1000 MW of grid-connected solar power projects

by March 2013—50% of which will be implemented using the solar thermal/CSP technology in a decision widely questioned by the domestic solar industry comprising of solar PV manufacturers. I am happy that the policy guidelines for the off-grid and rooftop systems were unveiled on 16 June.

The Indian industry has shown great enthusiasm to embrace the solar technology going by the reported number of MW-scale applications received in Rajasthan totalling more than 8000 MW against the Phase 1 target of 500 MW for solar PV and 500 MW for solar thermal projects. Of these, some 100 MW capacity is reportedly going to the “migration” projects—which were first registered under the Central Ministry’s generation based incentives scheme in 2008 or under the State-level solar policies of states like Gujarat etc. With some 8000 MW applications chasing a maximum basket of 150 MW of PV projects in the first year of Phase 1, the writing on the wall is clear— the Indian industry is more than ready to jump into the solar bandwagon if the government provides the policy framework and budgetary support necessary.

Apparently, the CERC (Central Electricity Regulatory Commission)—determined generic tariff of Rs. 17.91 per unit to be paid for 25 years—and valid for all projects starting this year and the next, has stoked the appetite of the investors and project developers. Unfortunately, the signals are that the government will choose the projects on the basis of competitive bidding

and those willing to share the maximum of the CERC tariff with the official power trading company (NVVN) will be selected first and so on. This will lead to aggressive underbidding and will likely result project developers agreeing to unviable tariffs leading to failed projects. That will be the end of the solar hopes for India. The way to avoid this pitfall is to eliminate non-serious players by fixing the eligibility criteria that pre-selects applicants on the basis of relevant technical experience and expertise in the renewable energy and/or conventional power sector, preferably in the solar sector, or in large infrastructure projects at the least. Such pre-selected project developers should then be selected on the basis of the earliest one to achieve financial closure being the first one to be selected and so on. The government can also prepone Phase2 allocation and bunch it with phase1 so that the present delay can be covered up and the overall target of Phase 1and 2 can be reached in time. The government should also take a re-look at its policy of 50 % quota for solar thermal/ CSP projects and 50% for solar PV projects in Phase 1 and re-allocate the capacities at the end of year 1 if sufficient number of projects are not received in any one basket, or if the market signals its overwhelming preference towards one technology over the other.

The other major issue facing the Indian industry is whether the government will mandate the use of ‘Made in India’ content in the solar mission. This issue has been debated quite regularly and there are strong arguments on both sides. The project developers want to retain the freedom to purchase products from wherever they can get them cheap and good. The Indian PV manufacturers, on the other hand, want to ensure that they are not pushed aside by the flooding of cheap imports from their northern neighbour. Their position is that the Indian PV cells and modules meet the highest international quality standards and

4 – Global Solar Technology South East Asia – Summer 2010

are regularly exported to US and Europe. It is also a fact that there is already some 500 MW of cells and 1000 MW of modules manufacturing capacity in India which is presently going through a rapid expansion phase. The fact is that the fledgling Indian solar industry needs to be nurtured and allowed to develop economies of scale through large volumes so that they can bring down the costs in line with their neighbour. Otherwise, the Indian solar industry would become a stillborn child.

At the same time, it is true that the country should welcome fresh investments and technologies and let competition flourish so that the best emerge to the top. The way to do that is to insist on global companies to invest into manufacturing in India. The examples around us are overwhelming—today more than 50% of the global manufacturing of solar PV is happening in China, although their own consumption is minuscule at present. But the manufacturing has led to an industrial base and ecosystem development which can start producing the benefits for the local economy any time. Similarly, the factory of First Solar, which has emerged as the largest solar company in the world in 2009 with 1.1 GW of manufacturing capacity, is located in Malaysia. The point is that manufacturing is shifting to low cost destinations in Asia and it would be unfortunate if India does not catch some of the new investments and manufacturing capacity going around. It would be impossible to implement a solar mission target of 20000 MW by 2022 on the basis of imported stuff.

The third issue is that of technical R&D and innovation. The whole world is waiting for a solar technological breakthrough which can bring down the cost and accelerate the march towards grid parity. The Indian scientific and research community can be enthused into this arena only when there is a sizeable Continued on page 37

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We’re turning solar possibilities into everyday realities.

We believe in the power of science to dramatically improve people’s lives—and protect the planet we all share. That’s why we continue to provide innovative photovoltaic solutions to help today’s leading manufacturers transform the sun’s potential into clean, efficient energy the world needs to thrive. It’s the promise of tomorrow, here today, powered by the solar innovation of DuPont.

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Copyright © 2010 DuPont. The DuPont Oval Logo and The miracles of science are trademarks or registered trademarks of E.I. du Pont de Nemours and Company or its affiliates. All rights reserved. ™

Industry News

Industry News Vikram Solar invests US$22.5 million in module manufacturing plant in West Bengal Vikram Solar Private Limited, part of Vikram Group of Industries of Kolkata, opened the solar photovoltaic module manufacturing plant at Falta, Special Economic Zone in the eastern State of West Bengal in March this year. The company has invested US$22.5 million (around Rs. 100 crores) in this project, with an initial capacity of 25 MW per annum.

Simultaneously, the company has started the process of expanding its capacity to 50MW before Q3 2010.

Regarding future plans, the company has plans for backward integration in the form of wafer and photovoltaic cell manufacturing, within a short period, with a total capital outlay of US$ 110 million (Rs. 500 crores). Vikram Solar has already provided employment to more than 100 persons by now, and once the full expansion is implemented, will be able to provide employment to more than 800 persons directly and indirectly with a focus on skill development and training in the High Technology Solar Industry.

IFC involved in solar power development in Thailand (photo) International Finance Corporation, the investment arm of World Bank, is investing US $1.7 million for a 20 percent stake in Solar Power (Korat 1) Co Ltd, the largest solar power plant in Southeast Asia, to expand private power generation while helping develop rural Thailand.

Solar Power (Korat 1) owns and operates a 6-megawatt grid-tied solar power plant in the Nakhonratchasima Province, an area with one of the best solar resources in Thailand. The company is majority owned by Solar Power Co Ltd or SPC, a Thai developer of large, grid-connected, solar photo-voltaic projects.

IFC’s investment in this first project represents the start of a partnership with SPC with plans to co-invest in some of the future solar projects as well as in SPC itself.

If fully exercised, IFC’s investment rights in SPC and its related companies could amount to as much as US$20 million.

SPC Korat 1 also has received a minority equity investment from the Energy for Environment Foundation and debt financing from Kasikorn Bank.

Ferro expands photovoltaic technology center capability in Singapore Ferro Corporation is expanding capability in its Suzhou, China, and Taipei, Taiwan, photovoltaic (PV) technology centers as part of a wide-ranging plan to support growth in the Asian marketplace.

Ferro’s existing technology center in Suzhou is currently being expanded to meet the increased demand from solar cell manufacturers in China. The new Advanced Technology Center in Taiwan is expected to be completed by the end of 2010 and will be equipped with stateof-the-art solar cell printing and firing equipment. Both labs will be capable of building prototype solar cells and will be complemented by a complete range of solar cell characterization instruments.

As a second part of an initiative to expand its photovoltaic technology capabilities in Asia, Ferro Electronic Materials has commissioned space in Singapore to open a Center for Excellence focused on new product development supporting Ferro’s rapidly growing solar materials product line in Southeast Asia.

The facility will expand Ferro’s research and development capabilities for next generation materials. The center will be located in Singapore Science Park and will house a solar materials laboratory to perform basic research and development activities, as well as technology staff to support the rapidly emerging solar market in Southeast Asia. www.ferro.com Tata BP Solar expands cell manufacturing capacity by 62% to serve growing solar market in India In a clear demonstration of its commitment to India and the growth of the solar energy market, Tata BP Solar, a

6 – Global Solar Technology South East Asia – Summer 2010

joint venture between BP Solar and Tata Power, has added a new production line of 32 MW of solar photovoltaic (PV) cells at its plant in Bangalore. With this expansion, the total cell capacity grew to 84 MW, and the module capacity reached 125 MW. Tata BP manufactures high quality, low-cost crystalline silicon cells (both mono- and multi-crystalline) and solar modules used to generate electricity from sunlight. www.tatabpsolar.com, www.bpsolar.com, www.tatapower.com First Solar hosts Secretary for the Environment of Hong Kong Hong Kong Secretary for the Environment, Edward Yau, visited First Solar’s German manufacturing plant to observe production of the company’s advanced solar technology and review its contributions to environmental sustainability.

Secretary Yau was in Germany to discuss opportunities for integrated energy and innovative technologies ahead of Hong Kong’s hosting of the C40 workshop. As one of the world’s most dynamic cities, Hong Kong is playing an active role in promoting sustainable energies for a low carbon city, involving engagement with key stakeholders in Hong Kong, mainland China, and the rest of the world. www.firstsolar.com Germany’s ib vogt secures first order to establish a PV factory in India ib vogt has been commissioned to undertake the factory design, planning and construction management for an Indian company to build its first PV factory in Southern India. The project has been running from the beginning of April 2010 and is expected to reach completion by the end of June 2011. “The final decision to sign the contract was made in light of not only the international recognition in the

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In touch with the future of solar energy.

Economically viable solar power is now within reach. Thanks to Oerlikon Solar. The world’s leading supplier of thin film silicon PV production equipment is on track to achieve grid parity by the end of 2010.

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Get in touch: www.oerlikon.com/solar Visit us at: DIREC India 2010 Expo Centre & Mart, Greater Noida, October 27-29, 2010; Booth S-52

Industry News

photovoltaic sector that ib vogt enjoys, but also the ongoing intensive consultation and preparation work that our companies have undertaken since 2009,” said Chris Buckland, director-projects, ib vogt GmbH. www.vogtgroup.com India switched on largest solar power plant for the energy security of farmers Union minister for new and renewable energy, Dr. Farooq Abdullah, on 16 June 2010 dedicated a 3 MW grid connected solar power plant at Yalesandra, Kolar district of Karnataka. The ceremony generated widespread interest since it came a day after the Indian government announced the guidelines for schemes under Jawaharlal Nehru National Solar Mission, which has set a target of generating 20 GW of solar power by 2022. Erected by the Karnataka Power Corporation Ltd, the state-owned power generating company, the plant will provide energy to 500 pump sets of 10 HP each, benefiting about 1,000 farmers.

The plant, built with crystalline solar PV technology on an area of 15 acres, has been set up at a cost of Rs. 58.75 crore (approx. USD 13 million). The plant is commissioned by Titan Energy Systems Ltd. of Secunderabad. www.titansolar.com, www.karnatakapower.com American Capital Energy, MSM Energy announce India solar foray U.S.-based American Capital Energy Inc. and MSM Energy announced the setting up of a joint venture to build and service solar photovoltaic systems in India. The company, ICE Solar, will start operations immediately and aims to install 100 megawatt of solar photovoltaic systems.

Madhav Muvvala, president of MSM Energy Holdings--a unit of New Jerseybased MSM Industries Inc., said the joint venture will capitalize on India’s National Solar Mission that has a target to generate 20,000 MW of solar energy by 2022. www.msmenergy.com XL Telecom ties up with Spain’s SDEM TEGA SA XL Telecom and Energy Limited, one of the leading Indian manufacturers of solar photovoltaic modules, has entered into a joint venture agreement with SDEM TEGA SA, a Spanish company with experience in implementing solar power projects as an EPC (engineering, procurement and construction) contractor in Europe. SDEM has installed over 30 MW of solar power projects in the

last two years. Under the terms of the agreement, SDEM will work with XL Telecom across the globe for bidding and executing solar power projects jointly.

Both the companies will initially explore the emerging India’s solar initiative along with the growing Latin America, North of Africa and Australian markets to capture a significant market share. XL anticipates the India opportunity at about $2 billion (approximately Rs 8,500 crore) and 500MW worth of projects in the next 12 to 24 months. www.xltelenergy.com

Solar Components places initial manufacturing order for portable solar chargers Solar Components LLC placed its initial manufacturing order for its Joos Orange portable solar chargers with Singaporebased Eastern Asia Technology Limited.

Solar Components plans to begin shipping its much-anticipated Joos Orange portable solar chargers during the third quarter of 2010. The Joos Orange from Solar Components sets a new standard in “Personal Solar Appliances” by delivering more than 2.5 hours of cell phone talk time for every hour of charging time—up to 20 times the powering capability of existing personal solar power devices. www.solarjoos.com Fidelis Energy of US setting up 5 MW solar energy facility in India Fidelis Energy Inc. reports the progress of the 5 MW solar energy facility near Jaisalmer, Rajasthan. The 5 MW project is part of a larger proposed 100 MW project and will be the first of its kind in India.

“It has been and exciting and rewarding journey for us as a company this past year in working towards the goal of becoming a pioneer in the solar industry in India,” said Mr. James Poole, president and CEO of Fidelis Energy Inc. “This is a very exciting time for solar and for the alternative energy sector worldwide, and we are proud to be

8 – Global Solar Technology South East Asia – Summer 2010

part of it.” www.fidelisenergyinc.com REIF announces Solar 2010 in New Delhi Renewable Energy India Forum (REIF) is an initiative of IPF Edge (the events division of IPFonline Ltd.). REIF is an effort to build a credible and dedicated platform to bring together the policy makers, academia, consultants, utilities, manufacturers, service and solution providers, financial institutions, technology experts, government and private and public enterprises for the renewable energy sector in India. The forum would come together and act as a growth engine for the entire sector by disseminating knowledge and promoting institutions, investments and government commitments, identifying policy issues, institutional frameworks and successful initiatives thus paving the way for adoption of best practices across the country. The first venture of REIF is Solar 2010 Conference & Exhibition, which is scheduled to be held on 21-22 September 2010 at Hotel LaLiT, New Delhi. For details please contact: Rajeev Kumar at rajeev@ipfonline.com or call +91 9810381293.

SunTechnics builds one of the largest photovoltaic plants in India SunTechnics, in collaboration with Photon has erected in India one of the largest photovoltaic plants in the country.

With the 3-megawatt-strong power plant, SunTechnics will contribute considerably to the power supply of the local rural population around the small town of Itnal Continued on page 36

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Global Solar Technology South East Asia – Summer 2010 – 9

Flexible silver paste enables thin-film photovoltaic flex solar cells

Flexible silver paste enables thin-film photovoltaic flex solar cells

Dr. Hong-Sik Hwang, Lee Kresge, James Slattery, and Dr. Ning-Cheng Lee, Indium Corporation, Clinton, NY A flexible high performance Ag metallization paste, LTTF-6363, has been developed for thin film photovoltaic flex solar cells. The binder of the paste is soft epoxybased resin system. Compared with a thermoplastic paste system, LTTF-6363 exhibits superior adhesion and is flexible. These features enable the deployment of flex solar panels where tolerance against rolling or bending is critical.

LTTF-6363 also displays excellent print characteristics and non-slump performance.

This is extremely important for maximizing the effective open areas on solar cells.

LTTF-6363 exhibits very good solderability, thus allows easy soldering connection with other electronic devices.

Keywords: Photovoltaic, Solar Cell, Metallization Paste, Flex, Thin Film, Volume Resistivity, Contact Resistance

Introduction With fossil fuel price soaring, solar energy becomes a vital energy alternative. Although silicon photovoltaic solar cells account for over 95% of the solar cells produced today, copper-indium-gallium diselenide (CIGS), amorphous silicon and cadmium telluride (CdTe) thin film cells hold promise for rapid growth. These thin film photovoltics can be deposited not only on glass, plastic or metal substrates but also on flexible substrates, which offer the advantage of roll-to-roll processing, thus significantly reducing manufacturing costs. Furthermore, solar cell on flexible substrates allows for easy deployment of solar panels, leading to much wider applications. However, the marginal flexibility performance of silver metallization pastes in use today severely restricts the practical use of flexible solar cells. In addition, the slump of the pastes after print reduces the effective exposure area to sun considerably. This paper describes a new highly flexible, non-slump silver metallization paste which can be cured at temperatures below 200˚C. Also discussed are physical properties of the uncured and cured paste, including contact resistance, adhesion stability after humidity exposure and substrate bending and UV resistance.

Quest for flexible silver paste Several polymeric binder systems were investigated for their potential as a

flexible silver paste (Table 1). Paste A was a commercial Ag paste and was used as a control. Other than the control, all pastes contained 92 w/w % Ag for the binder evaluation. Once a binder was selected, the paste was further optimized in Ag content.

The potential as a flexible silver paste was assessed by measuring the contact resistance of cured paste on ITO-coated CIGS substrate after humidity and bending treatment. Apparently, besides flexibility, other properties also have to meet the requirements, such as contact resistance stability against thermal cycling and UV exposure, bulk resistance, volume resistivity, solderability, printability and slumpresistance. The experimental methods for the aforementioned tests are described in the following section.

Experimental 1. Volume resistivity A line (width: 2 mm, length: 4.5 cm) of the metallization paste was printed through a stencil (thickness: 0.1 mm) on a glass substrate and cured at 165˚C for 10 min.

The bulk resistance was measured for 2 cm length of the line with a four-wire microohm meter (Biddle Instruments, Blue Bell, PA). Volume resistivity was calculated by the following equation: Volume resistivity (mΩ∙cm) = [measured bulk resistance (mΩ) x line width (0.2 cm) x line height (cm)] / line length (2 cm).

Paste

Binder system

Ag load (w/w %)

A

Thermoplastic – based

93

B

Medium epoxy-based

92

C

Soft epoxy-based

92

D

Hard epoxy based

92

E

Epoxy resin/acrylate resin-based

92

F

Soft epoxy resin with smaller Ag flakes

92

Table 1. Ag metallization pastes studied.

10 – Global Solar Technology South East Asia – Summer 2010

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Flexible silver paste enables thin-film photovoltaic flex solar cells

substrate through the 0.5 cm distance. The bulk resistance was considered a constant and was ignored. 4-10 measurements were made and the average values were used. Bulk resistance of each line was measured through a 20 mm length with a Fluke 189 True RMS multimeter, and the conductance contribution of the ITO layer was ignored. This design was used for all other tests including bending, 85˚C/85% RH condition, UV exposure and thermal cycling tests.

2. Contact resistance on Cu For a quick evaluation of the metallization paste for contact resistance, the contact resistance on OSP-coated Cu was measured. The pastes giving relatively good results in this test were further evaluated for the contact resistance on an ITOcoated CIGS substrate or on ITO coated glass. 40 short lines (1.41 mm width x 4 mm length x 0.1 mm thickness) were printed on the FR4 board having OSPcoated copper lines (Figure 1) with 80 overlapping area (1 mm x 1.41 mm). The bulk resistance of 20 mm x 1.41 mm x 0.1 mm paste was determined by printing a long line of paste with 1.41 mm line width across two Cu lines separated by 20 mm, then measuring the resistance between the two Cu lines.

Specific contact resistance was calculated by the following equation:

4. Flexibility—bending test The four-line sample of the ITO-coated CIGS substrate was bent against a 6 mm diameter pin. Each cycle was bent forward and backward alternatively, with orientation of lines being vertical to the pin axis. Contact resistance was measured using the micro-ohm meter. Adhesion was examined visually. The bending test was applied to samples after 85°C/85%RH treatment for 0, 3, 7 and 14 days, respectively. The contact resistance was measured after bending for 0X, 4X, 8X, 16X and 32X. Besides contact resistance, the possible occurrence of break or peeling off was also examined.

Specific contact resistance, mΩ/ mm2 = (the measured overall resistance, mΩ - bulk resistance of the paste, mΩ) / the contact area, mm2.

3. Contact resistance and bulk resistance on ITO-coated CIGS substrate or ITOcoated glass Two pairs of grid lines (height: 51 micron, width: 254 micron, length 2.5 cm, distance between two lines: 0.5 cm) were printed through a stencil on the ITO coated CIGS substrate (ITO/CdS/Mo/ stainless steel) solar cell sheet (Figure 2).

Contact resistance was measured between two lines using the Biddle micro-ohm meter. The large half-circle pads are for clip attachment, which applies current.

The small pads are for probe contact, which measures the voltage. The resistance measured contains bulk resistance of the

5. Humidity, thermal cycling, and UV treatments The humidity treatment test was done at 85˚C/85%RH. The thermal cycling test was conducted with the Blue M thermal cycling chamber (Blue M Electric, ETC04D-E). The temperature cycle range was -55˚C ~ 125˚C with one hour of cycling time. The UV chamber test was performed using Accelerated Weathering Tester (Q-LAB/SE with Solar Eye Irradiation Control). The intensity of the light was 1.20 W/m2/nm (@ 313nm) with UVB lamp.

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Figure 2. Print pattern of paste on ITO-coated substrates.

6. Solderability test A line (0.1 mm thickness x 2 mm width x 4.5 cm length) of the metallization paste was printed on a FR-4 substrate and cured on the hot-plate (170˚C, 10 min). Three 6.25 mm diameter (0.25 mm thickness) lines of a no-clean solder paste (Sn3.8%Ag-0.7%Cu, Type3) were printed

Figure 3. Contact resistance of paste A in bending test with and without 85/85 pre-conditioning. For 85/85 treated samples, the cured Ag paste peeled off beyond the bending data points.

Figure 1. Drawing of contact resistance test coupon, with OSP-coated Cu pattern on FR-4 substrate.

Figure 4. Contact resistance of paste B in bending test with and without 85/85 pre-conditioning.

Figure 5. Contact resistance of paste C in bending test with and without 85/85 pre-conditioning.

Global Solar Technology South East Asia – Summer 2010 – 11

Flexible silver paste enables thin-film photovoltaic flex solar cells

on the cured metallization paste and reflowed on the hot plate (250 ˚C, 3 min).

The solderability is reflected by the solder coverage area on the cured metallization paste, and the result is expected to be parallel to that of hot bar soldering or hand soldering.

before any treatment in order to assess the effect of pre-conditioning. Before the 85oC/85%RH treatment, the commercial paste A showed an increase in contact resistance with increasing bending number.

This is attributable to the poor adhesion of thermoplastic binder toward substrate.

This poor adhesion was further aggravated by 85oC/85%RH pre-conditioning, and consequently resulted in peeling off upon bending, as shown in Figure 3. In the case of three days of pre-conditioning, the paste peeled off after merely 4X bending treatment, indicating a total lack of compatibility with flexible solar cell applications.

On the other hand, 85oC/85%RH pre-conditioning caused a decrease in contact resistance, presumably through forming hygroscopic leakage current paths.

Figures 4, 5 and 6 show the bending data of epoxy systems. No paste peeling off the substrate can be discerned, and the contact resistance generally decreases with increasing bending number.

Epoxy systems in general promise superior adhesion toward substrates, therefore minimizing the chance of delamination after repeated bending.

In the mean time, bending very likely

7. Contact resistance measurement using TLM (transmission line model) Contact resistance using TLM was measured with a 1.5 cm x 6 cm substrate.

AZO/glass and ITO/glass were used as substrates in this experiment. The paste was printed as 3 mm x 3 mm squares with 0.6, 0.9, 1.2, 1.5, 1.8, 2.1, 2.4 and 2.7 mm gaps. The paste was cured at 165˚C for 10 min. Resistances were measured between paste pads with the different gaps. The intercept at the y-axis was calculated from the graph of resistance (ohm) vs. distance and recorded as the contact resistance.

Results 1. Flexibility—bending test The contact resistance stability of pastes A, B, C and D against 85°C/85%RH and bending are shown in Figures 3, 4, 5 and 6, respectively. The contact resistance was normalized against initial value

promotes piercing of Ag flakes through the epoxy binder, thus allowing for a better contact with the electrically conductive substrates, and consequently resulting in a reduced contact resistance. The decrease in contact resistance with increasing bending is more profound for softer epoxy system, as shown in Figure 7. Presumably a softer epoxy can be pierced through more readily.

Humidity conditioning did not cause significant effect on the contact resistance for the epoxy system, as indicated by the lack of trend between contact resistance and 85oC/85%RH pre-conditioning time.

In general, an acrylate-based binder shrinks more than an epoxy-based binder, and therefore promises a lower bulk resistance. On the other hand, an acrylate-based binder often yields a weaker adhesion than an epoxy-based binder.

Therefore, a system with mixed acrylate resins and epoxy resins may or may not improve performance. The flexibility of a series of mixed acrylate/epoxy resins system with increasing acrylate fraction was assessed by monitoring the contact resistance and bulk resistance against a bending treatment.

As the portion of the acrylate resin increased, bulk resistance was reduced

Figure 6. Contact resistance of paste D in bending test with and without 85/85 pre-conditioning.

Figure 7. Contact resistance of epoxy systems in bending test.

Figure 9. Contact resistance of pastes on Cu with increasing 85/85 conditioning time.

Figure 8. Bulk resistance of mixed acrylate/epoxy resins system with increasing acrylate fraction.

Figure 10. Contact resistance of pastes on Cu with increasing number of temperature cycles.

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Figure 11. Contact resistance of pastes on Cu with increasing UV conditioning time.

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Flexible silver paste enables thin-film photovoltaic flex solar cells

(Figure 8) while the contact resistance scattered around 1.3 ohm without a trend. When 60% of acrylate resin was incorporated, the printed paste lines were peeled off after 8X bends. Overall, system with 40% acrylate resins showed the best result for bulk resistance, contact resistance and adhesion, and the paste with 92% Ag content was designated as Paste E for additional study.

of this paste, which was further weakened during thermal cycling. Contact resistances of other pastes slightly increased with increasing cycle number.

The change in contact resistance in the UV chamber was negligible for all six pastes tested, as shown in Figure 11.

The effect of humidity, thermal cycling, and UV treatment on bulk resistance was also measured. Figure 12 shows bulk resistance decreased during in 85oC/85%RH treatment. The paste E containing epoxy/acrylate resins showed much lower bulk resistance than other pastes and stayed as the lowest.

On the other hand, all pastes showed slightly lowered bulk resistance in the thermal cycling chamber, as shown in Figure 13. For pastes C and F, both with soft epoxy resin, the bulk resistance decreases rapidly initially, then reduces gradually with increase in temperature cycling number.

The UV chamber treatment didn’t change bulk resistance of the samples (Figure 14).

2. Effect of 85°C/85%RH, thermal cycling, and UV aging Figure 9 shows contact resistance of all pastes on Cu after 85°C/85%RH conditioning. Other than paste D, all pastes exhibit a decreasing contact resistance with increasing humidity treatment, presumably through forming a hygroscopic leakage current path. Paste D employs hard epoxy resin, suggesting a high glass transition temperature hence a slow moisture diffusion rate through the binder.

This accordingly will result in insensitivity toward 85oC/85%RH conditioning.

The paste E that contains epoxy/ acrylate resins showed significant increase in contact resistance, as shown in Figure 10. This is attributed to the weak adhesion

Figure 12. Effect of 85°C/85%RH conditioning on bulk resistance.

Figure 15. Effect of Ag content on contact resistance, bulk resistance and volume resistivity. Ag paste was printed onto ITO on glass.

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lines need to be connected to electronic devices by soldering. In this case, solderability of the conductive line is important. All six pastes were evaluated for wetting property. Paste A didn’t show any wetting at all. Paste D with hard epoxy resin showed a moderate wetting. Pastes B, C, E and F showed good wetting.

Binder of choice Based on the bending test data (Figures 3 to 7), Paste C with soft epoxy is better than Paste B (medium epoxy) and Paste D (hard epoxy) in achieving low contact resistance under flex applications. Paste D is also not desirable based on the solderability consideration (see Section 3).

Based on the temperature cycling data (Figure 10), Paste E is not desirable due to poor adhesion.

Comparing Pastes C and F, it can be seen that a smaller Ag flake (in Paste F) contributes to a slightly lower contact resistance (Figures 10 and 11), but a quite higher bulk resistance (Figures 12 to 14).

The latter can be attributed to a greater extent of discontinuity of small flakes.

Overall, a soft epoxy-based binder system is desired for flex solar cell

3. Solderability test In some applications, the metallization

Figure 13. Effect of temperature cycling on bulk resistance.

Figure 16. Effect of Ag content and bending on contact resistance of paste using soft epoxy resin system.

Figure 14. Effect of UV conditioning time on bulk resistance.

Figure 17. Contact resistance of paste with soft epoxy resin binder and 95% Ag when tested against bending treatment. Samples were pre-conditioned at 85/85 from 0 to 14 days.

Global Solar Technology South East Asia – Summer 2010 – 13

Flexible silver paste enables thin-film photovoltaic flex solar cells

Figure 18. Contact resistance of paste with soft epoxy resin binder and 94% Ag when tested against bending treatment. Samples were pre-conditioned at 85/85 from 0 to 14 days.

applications, and a larger Ag flake helps in achieving a lower bulk resistance.

AG content optimization 1. Electrical properties of steady state With a soft epoxy-based binder system being selected, the next step is to optimize the Ag content in order to achieve the best current carrying capability while still retaining the flexible feature. Figure 15 shows the bulk resistance, contact resistance and volume resistivity for Ag content from 91 to 98% (w/w). Also

shown are the bulk resistance (0.80 ohm), contact resistance (3.23 ohm) and volume resistivity (18.0 μ ohm-cm) of the control Paste A, with each value marked on the Y and Y’ axis.

The contact resistance is virtually a constant regardless of the Ag content and is slightly higher than Paste A. The bulk resistance shows a very moderate concave curve, with minimum value 0.63 ohm around 94-95% Ag which is lower than Paste A. The volume resistivity decreases initially, reaching the minimal value 24 μ ohm-cm around 96%, then increases again with increasing Ag content. The minimal value is higher than Paste A. 2. Flexibility The cured pastes with Ag content equal to or greater than 96% were fairly brittle and hence were ruled out for further evaluation. For Ag content ranging from 92% to 95%, the contact resistance upon bending treatment without humidity pre-conditioning is shown in Figure 16.

No breakup could be discerned for all samples, and all pastes showed decreasing contact resistance with increasing bending treatment, with 92% Ag sample exhibiting most significant decrease in contact resistance.

However, for samples pre-conditioned at 85oC/85%RH, damage caused by humidity was noticeable for 95% Ag, as shown in Figure 17. After 85oC/85%RH pre-conditioning for seven days, breakup in the paste line was recognizable after 8X bending treatment, although contact resistance did not deteriorate significantly.

After pre-conditioning for 14 days, the paste line was broken and electrical discontinuity was registered after 8X bending.

When the Ag content was decreased down to 94% or below, no electrical discontinuity or physical deterioration could be discerned, as demonstrated in Figure 18 for 94% Ag paste. Accordingly, the optimal Ag content is determined as 94% w/w when considering electrical property, stability against humidity, and flexibility. This optimal composition for low temperature thin film Ag metallization paste is designated as LTTF-6363.

Slump The soft epoxy-based binder system LTTF-6363 was formulated to resist cold slump after the print. Furthermore, it gels quickly upon heating, thus preventing hot slump as well. Figure 19 shows the photos of pastes printed for LTTF-6363 and the

Figure 19. Photos of LTTF-6363 (left) and Paste A (thermoplastic, right) after print with the use of slump stencil IPC-A-20 specified in J-STD-005. The aperture openings are 0.20 x 2.03 mm and 0.33 x 2.03 mm, and the stencil thickness is 0.10 mm.

Figure 20. Cross-section pictures after printing a paste through 50 microns thick, 250 microns wide stencil and then curing at 165 oC for 10 min. LTTF-6363 (left), Paste A (thermoplastic, right).

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Flexible silver paste enables thin-film photovoltaic flex solar cells

control thermoplastic-based Paste A. LTTF6363 held the print shape very well, while that of Paste A experienced significant slump. The gap in the slump behavior between the two materials further enlarged after curing.

Figure 20 shows the cross-sectional pictures of cured thin lines of LTTF-6363 and Paste A printed through 50 microns thick, 250 microns wide stencil. After curing, the width of Paste A was about 60% wider than that of LTTF-6363. In other words, Paste A blocked 60% more sun light when compared with LTTF-6363.

As the LTTF-6363 showed very promising results in many aspects, the contact resistance of this paste was measured by TLM (transmission line model) and compared with the control paste A (Table 2).

Discussion It is interesting to note that, while the contact resistance of the two pastes is about comparable, LTTF-6363 displays a lower bulk resistance but a higher volume resistivity than that of Paste A, as shown in Table 3. First question, how does this happen? Second question, for solar cell application, is the bulk resistance or the volume resistivity more meaningful for higher energy efficiency?

Volume resistivity was calculated based on theoretical shrinkage by volatile evaporation (shrinkage factor: 100% volatile volume %) To answer the first question, the

Substrate

LTTF-6363

Paste A

Contact resistance on AZO/glass, Ohm•cm2

0.18

0.21

Contact resistance on ITO/glass, Ohm cm2

0.08

0.06

Table 2. Contact resistances of LTTF-6363 and paste A on AZO/glass and ITO/glass measured by TLM method.

Paste

LTTF-6363

Paste A

Ag % (w/w of paste)

94

93

Volatile (volume % of paste)

7.90

24

Contact resistance, ohm

3.42

3.23

Bulk R measured, ohm

0.63

0.80

Volume resistivity, micro-ohm•cm

26.6

18.0

Volume resistivity was calculated based on theoretical shrinkage by volatile evaporation (shrinkage factor: 100% - volatile volume %)

Table 3. Paste composition and electrical properties. Tests done with ITO/glass substrate.

process of the two metallization pastes can be reviewed, as shown in Figure 21.

Upon printing, the wet paste volume of the two pastes, LTTF-6363 and A, was identical, as dictated by the stencil pattern.

However, after curing, the dry paste volume is no longer identical, with Paste A being considerably smaller than LTTF6363. This is a result of a greater volatile content in Paste A than that of LTTF-6363.

By definition,

exhibits superior adhesion and is flexible.

These features enable the deployment of flex solar panels where tolerance against rolling or bending is critical. LTTF-6363 also displays excellent print characteristics and non-slump performance. This is extremely important for maximizing effective open area on solar cell. LTTF6363 exhibits very good solderability, thus allowing easy soldering connection with other electronic devices.

Volume Resistivity = Bulk Resistance X Line Cross-section area /Line length

Although Paste A exhibits a higher bulk resistance, its cross-sectional area is substantially smaller. With line length being identical for both pastes, this eventually results in a lower volume resistivity for Paste A than LTTF-6363.

To answer the second question, since paste line is used for collecting current, and the current allowed is inversely proportional to the bulk resistance (according to relation V = I x R), a lower bulk resistance means a greater current allowed. Volume resistivity becomes meaningful only when the dry paste volume is the same for pastes being compared.

Figure 21. Schematic of metallization paste process.

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Conclusion The flexible high performance Ag metallization paste LTTF-6363 was developed for thin film photovoltaic flex solar cells. The binder of the paste is soft epoxy-based resin system. Compared with thermoplastic paste system, LTTF-6363

Global Solar Technology South East Asia – Summer 2010 – 15

Advanced screen printable thin film PV silver conductor compositions

Advanced screen printable thin film PV silver conductor compositions Jay R. Dorfman, DuPont Microcircuit Materials, Research Triangle Park, N.C., USA and Vince Arancio, DuPont (UK) Ltd, Bristol, UK

A series of new thin-film photovoltaic (PV) front-side silver conductor compositions has been developed for CIGS and a-Si thin-film PV cells.

These new conductors provide outstanding adhesion to various transparent conductive oxides (TCO’s) such as indium tin oxide (ITO). Additionally, these front-side silvers exhibit very high conductivity and extremely low contact resistance to the TCO. They have been formulated for screen-printing manufacturing operations and are easily processed at 140˚C for 5-10 minutes. Reliability studies on these conductors have shown very good stability out to 1000 hours of storage at 85˚C/85% RH. The details of the compositions and their properties as well as the typical construction of the thin-film cell using these front-side silvers will be discussed.

Keywords: Front-Side Silvers, Thin Film PV, Transparent Conductive Oxides, Ag Electrode Pastes

Thin-film photovoltaic (PV) solar cells are CIGS becoming more prevalent in the marketplace. The drivers for the growing adoption of thin-film PV cells include lower cost ZnO, ITO 2500 Å structure vs. conventional silicon cells, flexibility of the cells and the ease/cost of CdS - 700 Å manufacturing. Thin-film cells are usually segmented based upon the semi-conductor CIGS 1-2.5 µm or absorber used. This would then include CIGS, a-Si, CdTe, and organic (dye conversion) as the different categories of thin-film Mo - 0.5-1 µm PV cells. All but CdTe cells use a front side silver grid as part of the cell construction.

Glass, Metal Foil, A typical construction is shown in Figure 1.

Plastics The silver grid is applied on top of the transparent conductive oxide (TCO), Figure 1. Typical thin-film construction. which is usually indium tin oxide (ITO).

Zinc oxide (ZnO) is also being investigated by some manufacturers. The grid pattern shadowing. of silver is usually applied by the method of 5. Reliable Performance high-speed screen printing of polymer thick Need long term Reliability. Accelerated life film (PTF) silver pastes. Screen printing is a testing carried out at @ 85˚C/85% R.H. useful method for silver grid formation in An assessment of a new generation of thin-film cells as the required thicknesses screen-printable Ag electrode pastes for (15-25 microns) are able to be applied in thin-film PV cells was carried out. Four one pass. PTF silver pastes for this type of PTF Ag pastes were evaluated as can be application have some key requirements. seen below. These are DuPont™ Solamet® They are as follows: PV427 photovoltaic metallization pastes, which was the original DuPont Ag paste 1. Adhesion to Transparent Conductive offering, Solamet® PV410 and Solamet® Oxides (TCO) PV412, which are newly commercialized Ag Need excellent adhesion for durability. pastes, and the most recent experimental Common measurement technique uses the formulation -35B. The details of the evaluaScotch tape test. tion are shown below: 2. Resistivity Lowest possible resistance is required to Processing maximize current and minimize cell losses.

1) Printing 3. Low Contact Resistance to TCO Screen printing using stainless steel, Minimize series resistance losses and allow 325 mesh, 25 µm emulsion, 45˚ angle finer printed tracks. Looking for low, single & 280 mesh 20 µm emulsion, 45˚ angle digit mΩ. cm2 values (Measured using Transmission Line Model).

2) Drying 4. Fine Line Performance a) Box oven: 130˚C/20min Track widths vary. They range from 250 b) Box oven: 180˚C/30min µm down to 100 µm. Need to meet current b) Web Drier: more efficient and so less carrying requirements while minimizing

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Advanced screen printable thin film PV silver conductor compositions

time needed 3) Substrates Used: ITO coated Polyester (PET) film ITO coated Glass Discussion of results: The diagram in Figure 2 shows a typical study of resistance of a circuit plotted as a function of drying time and temp.

Note that PV410 shows reduced resistivity vs. PV427 and also note that increased temperature and time also reduces resistivity. This is a general trend found for all compositions studied.

Print behaviour on ITO film Another key aspect of a PTF Ag electrode in thin-film solar cells is the resolution capabilities of the paste. Smaller track width minimizes shadowing in the solar cell and is desirable. Note the results in Figure 3, which show the much improved resolution of PV410 and PV412 vs. PV427.

The data show that PV410 & PV412 have improved fine line performance (i.e. track widths of 123 µm & 125 µm vs. 161 µm when printed through a 100 µm screen opening) and therefore less shadowing effects.

Resistivity comparison A summary of the sheet resistivities of the three PTF Ag pastes is shown in Figure 4.

Note the gradual reduction in resistivity from18 mΩ/sq for PV410 to 14 mΩ/sq for

Figure 2. A typical study of resistance of a circuit plotted as a function of drying time and temp.

PV412, and 10 mΩ/sq for -35B (for 200um track width). Additionally, tape adhesion testing of PV410, PV412, and -35B show excellent results in that no Ag paste is removed from the substrate.

Transmission line model (TLM) Another key property of a PTF Ag electrode paste is the contact resistivity. The contact resistivity is a key property as it provides an indication of losses and cell performance. Ideally, a contact resistivity

PV427

of <10 mΩ.cm2 is desirable. As can be seen in Figure 5, the transmission line method (TLM) is used to calculate the Contact R. Measured contact resistivity data Note from the data that the Contact R of PV410 which is 6.9 mΩ.cm2 (Table 1) is a significant improvement over that of PV427 which is 24.0 mΩ cm2. PV412 shows even lower Contact R than PV410 and the lowest observed is for experimental composition -35B where values of 3.4

PV410

PV4xx

123 µm

125 µm

200 µm Tracks

100 µm Tracks

Measured Track widths = 161 µm Figure 3. The much-improved resolution of PV410 and PV412 vs. PV427.

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Global Solar Technology South East Asia – Summer 2010 – 17

Advanced screen printable thin film PV silver conductor compositions

¾¾ Contact between a conductor (eg Ag) and a semi-conductor (eg ITO) create an interfacial resistance, commonly referred to as “contact resistance.” ¾¾ Specific contact resistance (ρC) rpovides a good indicator of losses & cell performance—TLM test method is used to measure ρC. TLM Test Pattern Employed: 200 µm line length = d, 1 cm track width = W Track separation, L from 0.015 cm to 0.5 cm Established Technique Following isolation of tracks, resistance measurements are made (between tracks) while progressively increasing/decreasing track separation.

Figure 4. Summary of sheet resistivities of the three PTF Ag pastes.

 Resistance values are plotted vs. track separation

mΩ.cm are observed. Also note that just as was the case for sheet resistivity, increasing temperature decreases the value of the Contact R down to a minimum value that is characteristic of each composition.

2

Environmental Life Testing Finally, as can be seen in Figure 6, the longterm reliability testing of PV410, PV412 and -35B indicates outstanding performance when exposed to 85C/85% R.H. for 1000 hours. This roughly converts to 25 years of simulated exposure. Note that the contact resistivities of PV410, PV412 and -35B all remain stable over this time period. Other properties follow as well.

Summary and Conclusions: 1. Significant improvements were seen in the progression PV427, PV410, PV412 35B. These include less flow-out, higher conductivity, lower contact resistance and improved adhesion, all resulting in a significant cell efficiency improvement.

Reliable performance under accelerated life test conditions was also shown.

2. Second-generation metallizations PV410 and PV412 have therefore demonstrated improved & reliable performance for use in thin film PV cells. Experimental composition -35B extends this improvement for even better performance.

3. A patent application has been submitted, and the technology will be used as a platform for further developments, to include • meeting reduced resistivity demands for other thin film technologies; meeting alternative rheology requirements for other high volume deposition, and; • methods which include rotary printing.

Vince Arancio graduated from De Montfort University in Leicester, UK, with an electronic engineering degree. He worked in the semiconductor industry before joining DuPont Microcircuit Materials. Vince is a senior technical specialist, supporting the European region and has responsibility for various markets utilizing low temperature electronic compositions. These include thin-film photovoltaics, biomedical

Graph—Resistance, R(Ω) vs Track separation L(cm)

Figure 5. The transmission line method (TLM) is used to calculate Contact R.

Ag’s dried at: 200 µm Tracks

130˚C on ITO PET

180˚C on ITO glass

PV427

PV410

PV410

PV412

RC (ohm)

1.55

0.66

0.35

0.32

0.26

LT (µm)

279

117

298

233

181

-35B

Calc Rsh (Ω/)

55.5

56.6

11.8

13.7

14.3

Lineararity R2

0.9994

0.9991

0.9962

0.9986

0.9981

24.0

6.9

5.5

4.6

3.4

ρC(mΩ.cm2)

Table 1. Measured contact resistivity data.

Figure 6. Long-term reliability test of PV410, PV412 and -35B indicates outstanding performance when exposed to 85C/85% R.H. for 1000 hours.

sensors, heating, electroluminescent lamps and RFID antenna.

Jay R. Dorfman received his Ph.D. in inorganic chemistry from North Carolina State University. After receiving a NIH Postdoctoral Research Fellowship to study at Harvard University, he joined DuPont in 1984. Over the last 26

18 – Global Solar Technology South East Asia – Summer 2010

years at DuPont, he has been the principal scientist primarily responsible for Research and Development of DuPont Microcircuit Materials’ polymer thick film pastes for applications such as electroluminescent lamps, biomedical Sensors, RFID, and most recently, thin-film PV conductors.

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Interview

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‘Printing’ PV electrodes onto flexible substrates

‘Printing’ PV electrodes onto flexible substrates Mark David Miller, Extrusion Dies Industries, LLC (EDI)

“I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait ‘till oil and coal run out before we tackle that.” —Thomas A. Edison (1931) Slot die coating, widely used in the production of lithiumion batteries and liquid crystal displays (LCDs), promises to increase the speed and reliability of electrode coating while reducing its cost. It can also improve productivity, precision and optical properties for other components of thin-film PV systems. This paper introduces slot die coating for PV cell technology and discusses the advantages that slot die coating presents over other techniques for use with flexible solar systems, such as vacuum deposition, spray coating, ink jet printing and roll coating.

Photovoltaic (PV) cell technology is moving toward flexible or thin-film systems as the means of achieving the economies of scale needed to make Edison’s prescient vision of unlimited solar power a reality. Thinfilm PV structures have an electronically-active core consisting of fluidized anode and cathode materials that have been coated or “printed” (to use the semiconductor

industry term) onto flexible substrates.

Taking the form of slurries with high solids content, these fluidized electrodes are less costly to produce than the crystalline silicon in rigid solar panels, and they make possible high-volume production in reel-toreel or continuous web coating processes.

One such process is slot die coating.

It promises to increase the speed and

Keywords: Flexible Substrates, Slot Die Coating, High Volume Production, Reel-toReel, Continuous Web

Figure 1. Complete fluid-coating line in laboratory at EDI’s headquarters in Wisconsin is shown applying coating to copper foil.

20 – Global Solar Technology South East Asia – Summer 2010

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‘Printing’ PV electrodes onto flexible substrates

steel body sections that enclose a precisionreliability of electrode coating and reduce bolted together and may be disassembled its cost. In addition, slot die coating and split apart for ease of cleaning. In a engineered flow channel, or manifold, can also help to improve productivity, typical construction, the body of one type that has been machined into one of the precision and optical properties for other of slot die coating head is about 9 inches sections. A fluid delivery system or pump components of thin-film PV systems.

(230 mm) long in the machine direction meters the fluid to be applied to the Although they are thin and flexible, and 5 inches (127 mm) high; widths up substrate into the manifold. The fluid these PV systems are complex multi-layer to 180 inches (4.5 m) are available, as flows through the manifold and exits at a structures. There may be half a dozen opposed to a typical maximum of 85 slit-like opening between “lips” formed by active coatings besides the fluidized inches (2.1 m) for roll coating. Ultra-flat the two body sections. The substrate to be electrodes, such as UV blockers, protective flow surfaces are critical for applying coated is a film or metal foil that moves hard coats, antireflective substances and coatings that must meet the precision from reel to reel in a continuous strip, or other functional materials. In addition tolerances required in solar panel “web.” Depending on the slot die coating there are multiple types of polymer production. EDI can machine surfaces process used, the fluid coating either is films, along with with a flatness of 0.5 a reflective metal micron over a length foil, a number of of 1 meter. them serving as • Manifold. The substrates for the flow channel that is coatings. In their machined into the ultimate use on the die body includes rooftops of homes an entry port and a and buildings, such coat hanger-shaped structures would manifold. The nevertheless be widest segment of lower in cost and the coat hanger simpler to apply triangle, the exit than traditional slot, corresponds to rigid, discrete-panel the coating width. solar systems.

Besides distributing Slot die coating the coating fluid is widely used in that enters the die to the commercial this target width, the production of manifold maintains lithium-ion batteries its temperature, (which also require and ensures a the coating of uniform crosselectrodes onto web distribution. flexible substrates) The key factor and liquid crystal in achieving displays or LCDs optimal flow is the (which, like thin film contoured geometry solar systems, have of the manifold, Figure 2. In this close-up extracted from Photo 1, the slot die coating head is visible at left center, with lips demanding optical which has been pointed toward the copper foil web as it moves past the lip exit, propelled by a system of rolls. requirements). machined into Besides supplying the die bodies to companies in these industries, EDI builds exacting tolerances in accordance with the applied to the substrate directly from the slot coating die systems for manufacturers rheology, or flow properties, of the fluid. lips or traverses a short distance from the of rigid, discrete glass-panel solar systems, Each fluid has its own rheology—a kind of lips to the substrate, being drawn down in in addition to developing flexible, “fingerprint”—which is determined by an thickness by the movement of the substrate continuous-web systems. analysis of viscosity verses shear rate at a over the backing roll.

A number of other coating or specific temperature.

The main components of a slot die printing techniques are used for flexible • Back-up roll. This provides the precision system are: solar systems or are in various stages of surface for most coating techniques. The development for them. Chief among these • Fluid delivery system. The positivecharacteristics of the roll, such as its degree displacement pump provides a non-pulsing, are vacuum deposition, spray coating, of concentricity, will provide the basis for constant feed of fluid to the die. It is a ink jet printing and roll coating. The the interaction between the substrate, the critical piece of equipment that works in advantages that slot die coating presents fluid and the slot coating die. combination with an accurate line speed over these techniques are discussed later in • Die positioner. This adjustable carriage control to determine the coat weight, this paper. precisely positions the slot coating die at which is the amount of fluid applied to a the optimum angle and proximity to the given area of substrate.

Slot die system components and roll and isolates the die from vibrations • Die (also called a coating head). The die is operation that can affect coating application. It is a split into top and bottom sections that are A slot die is comprised of two stainless critical component for stabilizing the

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Global Solar Technology South East Asia – Summer 2010 – 21

‘Printing’ PV electrodes onto flexible substrates

• interaction between die and moving web.

The coating process can be optimized by using the positioner to adjust the angle of attack between die and substrate, the distance between the two, and the degree of offset between the lips of the die.

Slot die coating techniques Slot dies coating application can take several forms, but two methods are particularly relevant to thin-film solar systems.

Contact coating involves applying the fluid directly to a substrate, using the die lip to “wipe” the coating fluid onto it.

Coating thicknesses as low as 0.00075 inch (18 microns) are achievable.

For direct coating, EDI builds a range of adjustable-lip slot dies which have a flexible lip that is the key to fine-tuning the lip gap profile. This is important in applying slurries such as those used for electrodes, since slurry viscosity changes over the course of a production run and the die needs to be adjusted accordingly.

An adjustable-lip slot die can be controlled manually or by means of an automated gauge profiler.

Draw coating involves allowing the fluid to traverse a short distance between the lips of the die and the substrate and using the rotation of the backing roll to draw the fluid down to very low thickness.

The distance through which the drawdown takes place can be up to 0.012 inch (305 micron), and the coating thicknesses achieved can be as low as 0.00004 inch (1 micron). Besides its capability for much thinner coatings than are achievable with direct coating, draw coating is better suited for optically clear applications. On the other hand, this process typically runs at lower line speeds. Die lips are fixed rather than adjustable, and coating distribution is varied by means of interchangeable shims.

For draw coating applications, EDI builds a range of fixed-lip slot dies from which fluids can be drawn down by as much as 98%. In commercial uses involving many fluids and substrates, these dies have maintained cross-web coat weight tolerances within 3 to 5% even at coating thicknesses of only 0.00008 inch, or 2 microns. Besides the slot die system components enumerated above, the fixed-lip die system typically includes a vacuum box to remove air trapped between the coating (as it exits the die) and the approaching substrate surface.

For trial runs of slot die coating in a commercial roll coating operation, EDI has developed complete trial-size modules for both adjustable- and fixed-lip coating processes. Each module includes the die,

Figure 3. This complete slot die coating station with all components, from idler roll to backing roll, enables manufacturers to eliminate hours of setup in switching from roll to slot die coating as they carry out product and process development. The system can be rolled into place on coating lines.

At top center is Ultracoat V adjustable-lip slot die coating head, with lips pointing toward the roll. The containing structure of the coating station serves as a stabilizer and die positioner.

a fluid-delivery system, an adjustable die positioner, idler rolls and a backing roll.

These are unitized within a steel frame which maintains straightness during operation and adjustment. The coating station is mounted on casters and can be rolled into place in an existing production line.

Advantages of slot die coating The advantages of slot die coating over other coating techniques vary in importance depending on the technique with which slot die coating is compared. Overall, the advantages fall into three main groups: 1) production speed; 2) control over coat weight (the amount of fluid applied to a given substrate area) and cross-web distribution; and 3) raw material management.

The last area of advantage is attributable to the fact that, unlike spray and roll coating, slot die coating is a closed system with metered fluid delivery, preventing waste, contamination of the fluid and contamination of the factory environment.

Production speed is an inherent advantage of continuous web processes and an essential factor in the economic advantage of thin-film PV systems over rigid, discrete solar cells. Vacuum deposition, currently the most widely used coating technique for solar systems, builds up a coating surface molecule by molecule and appears to be the slowest option available.

Compared with other options such as roll coating, slot die coating provides

22 – Global Solar Technology South East Asia – Summer 2010

greater productivity. One reason is its flexibility in regard to the viscosity of the fluid being applied. Since a positive displacement pump delivers a constant supply of coating fluid to the slot die, the fluid can contain a higher concentration of solids, which in turn decreases the workload of downstream drying units. In addition, a slot coating die can be designed to run multiple fluids simultaneously through the use of multimanifold slot die technology.

Another productivity gain is possible through two-sided coating. In its work with manufacturers of lithium-ion batteries, EDI has developed systems in which two slot dies are deployed for simultaneously applying anode and cathode slurries to both sides of a substrate.

“Lane coating,” which applies continuous coated lanes in the machine direction alternating with uncoated lanes, allows for increased yield and reduction in fluid use. Lane coating has been employed successfully in applications of up to 48 separate lanes, each 20 mm wide and separate from other lanes by 10 mm gaps. The coating fluid has been applied in register on both sides—critical for preventing unbalanced energy densities.

Control over coat weight and cross-web distribution. Slot die coating provides the greatest available precision and consistency in the application of fluids to substrates.

This advantage is critical because in PV systems, as in lithium-ion batteries, electrical uniformity is directly dependent on uniformity of coating. Variations in electrode layers can reduce battery life, cause malfunctions, and even pose safety issues by generating spikes in current.

In batteries, thermal runaway has led to explosions. This is one reason why the automotive industry specifies that coating variations be held to less than 1.6% Cpk process capability for the batteries used for hybrid and all-electric vehicles.

Several aspects of the slot die system contribute to its exceptional control over coat weight and transverse distribution.

1) The fluid delivery system delivers fluid at a pulse-free, uniform rate. 2) Variations in coat weight can be adjusted for by coordinating the pumping rate and the line speed. 3) The manifold is designed in accordance with the rheology of the fluid to distribute the fluid uniformly. 4) Cross-web distribution can be fined tuned by means of the lip adjustment system (in flexible lip dies) or the body shim (in fixed-lip dies). And 5) The die positioner or support system positions the die for optimal fluid application.

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‘Printing’ PV electrodes onto flexible substrates

Figure 4. This schematic highlighting DuPont products for photovoltaic systems shows both conventional rigid-panel (crystalline silicon) and new flexible film solar systems.

Thin film systems are complex, multi-layer products that require a wide range of films and coatings. (Photo: DuPont)

Raw material management. The completely closed system of a slot coating die is of obvious value for clean-room operations and—combined with constant, pre-metered fluid delivery—provides other advantages, particularly over roll coating.

Whereas all of the fluid that goes into a slot die is applied to the web, only a portion of the fluid on the applicator of a roll coating system is actually deposited on the web. The remaining portion must be recirculated, resulting in contamination and waste.

Multi-layer PV structures include coatings and films Besides multiple coatings, each of which would require curing and thus could not be applied simultaneously with any of the others, a typical thin film solar system would include films produced from a variety of polymers. One possible structure, from sun-facing side to back side, might look like this: PET film with UV-block coating; EVA protective layer; PET barrier film; the multi-component PV core; a fluoropolymer or high-heat polyester spacer or insulator film; a reflective film; an aluminum foil layer; and an EVA back layer. A more elaborate structure currently in development has eight polymer films in addition to the metal foil and the PV core

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sandwich.

Besides slot die systems, another key product range at EDI is that of extrusion dies for film. EDI film dies are used in the solar, battery and LCD industries. Recent advances in die technology have increased the strength and consistency of films and enhanced their barrier properties, which are important for keeping solar structures moisture-resistant.

Though lower in PV efficiency than crystalline silicon used in rigid panels, the high-solids electrode slurry used in thin-film systems is less costly, and this economy, combined with the high speed and automation of roll-to-roll production, can bring down the cost of solar electricity generation. At the same time, the more extensive installations made possible by the thin film helps offset the losses in PV efficiency. Contractors would purchase the film in rolls and install it over a wide roofing area, increasing overall sun-gathering capacity and thus power generation. In short, thin-film PV systems promise to be the future of solar power generation—a future that slot die coating and advanced film production will help to make a reality.

Mark David Miller is the market development manager for Extrusion Dies Industries, LLC (EDI). He joined EDI in 2006 as project and manufacturing engineer.

Previously he spent nine years with 3M Company, where his responsibilities included R&D on applications involving slot and extrusion coating dies. Miller holds a Masters degree in polymer science and engineering from Lehigh University and a Bachelors degree in chemical engineering from the University of Wisconsin.

Global Solar Technology South East Asia – Summer 2010 – 23

Interview

Interview

Soni Saran Singh­— NMTronics India Pvt. Ltd. NMTronics is a leading tier one manufacturer’s representative of electronics production equipment in India. Now the company has become very active in the solar industry and is highly committed to bring the latest Japanese, Korean, German and Taiwanese technology to Indian customers. In a candid conversation with Global Solar Technology, Soni Saran Singh, executive director of NMTronics India Pvt. Ltd., spoke about the latest trend in the Indian solar industry, the company’s road map and the expectations for the upcoming SOLARCON India 2010 show.

Tell us briefly about your solar technology solutions business?

Our interest to enter into the solar technology business started around mid2009. As a technology oriented company, we did a detailed study of the solar industry to understand various technologies and the business model of this new arena.

During the learning phase, we understood that solar technology business in India is still at a nascent stage. Most major players have a low manufacturing capacity, and the need of the hour is a good service quality, which could be extended to the customers.

Once we understood this need, we made a roadmap to address different technologies.

The simplest was module assembly line, for which we had the in-house skill set, based on our existing line of business.

Our aim is to bring excellence in service and turnkey solutions in module and cell manufacturing line with the latest technology from leading technology companies from Japan, Korea, Germany & Taiwan. We plan to work with some of the premier research agencies of India, which will help us to understand the technology,

as well as to evolve and contribute in the development of this business.

National Solar Mission has set an ambitious target of 20 GW of solar power by 2022. What kind of capacity additions do you expect from the existing local solar cell and module manufacturers, in the short term and in the long run?

We have observed that in countries like Spain, Germany and Italy, where

24 – Global Solar Technology South East Asia – Summer 2010

government has supported solar technology, the markets have performed outstandingly well, and now the Government of India is treading the same path.

The ambitious plan of National Solar Mission explains to us the potential of solar business in India. Just to add to your comments, the government has kept a target of just 20 GW, and after that we will be able to attain grid parity and businesses

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Interview

SOLUTIONS FOR SOLAR INDUSTRY

BARTEC Dispensing Technology GmbH

Represented Exclusively in INDIA by:

will move ahead on their own.

We will see multifold additions of capacities both in short and long term to meet this requirement. It will require a lot of support from the equipment suppliers and service providers like us to achieve these ambitious targets.

Are you launching any new products at the upcoming SOLARCON India 2010 show scheduled in Hyderabad during 2830 July 2010? What are your expectations from this show?

NMTronics India represents Nisshinbo Mechatronics from Japan, which offers the best of technologies for module assembly line. We shall be focusing on their new laminator (PVL 2235), as this is one of the most popular for lamination in volume production of bigger size panels, most economically. The EL inspection system adds value to any of the existing module assembly line by catching most of the defects before lamination, thereby reducing scraps and improving quality. iNETest Technologies is launching combined tabbers & stringers (CTS) from Teamtechnik from Germany, which are amongst the best in the world. They can offer unmatched quality in soldering with most efficient operation cost. Please visit our Booth number #905 during the SOLARCON India 2010 show and we

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can explain to you in more detail about all these new launches.

We are also working on technology/ equipment for 16.4% average efficiency in poly-crystalline cell manufacturing at a very cost effective solution. At the same time, we might be able to give a wafer solution to all cell manufacturing companies for their backward integration plan.

SOLARCON India focuses on emerging technologies in solar from all over the world. SEMI has invited the worlds’ most renowned solar professionals for the conference, which will attract all the key players in this industry. It is a perfect stage to offer and initiate interaction between the suppliers and buyers. There are many suppliers like us who shall be showcasing new technologies and products, which will be very interesting for all the visitors of the show.

We have very high expectations from SOLARCON India 2010. Last year, when we participated in this show, it gave us inquiries of about 200 MW module assembly (since we focused only on this business). Some of them are on the verge of finalization now.

accelerate the growth of the company.

We are working at a much faster rate than to our expectations. NMTronics is known for its quality of service in India.

We are able to represent some very good technology providers in India, and have got an overwhelming response from our customers.

How would your solar division fare during FY 2011?

Our Solar division will help NMTronics to attain its long term vision, and

Global Solar Technology South East Asia – Summer 2010 – 25

Flexible non-contact laser soldering for solar cell strings

Flexible non-contact laser soldering for solar cell strings Andreas Kriegler, teamtechnik, Freiberg am Neckar, Germany

Today, the process to connect individual solar cells and solar strings with conductive ribbon is almost entirely automated.

With cells becoming increasingly thinner and therefore more sensitive, the challenges facing this technology are growing.

Cells, ribbons and flux have to be soldered together in various combinations at lower cycle times in a dependable and capable process.

Only a minimum of thermal stress can occur in order to avoid stress cracks on the cell and the cell-ribbon connections.

Keywords: Stringing, Laser Soldering, Solar Cell Strings

Todayâ&#x20AC;&#x2122;s standard stringing technologies use different soldering processes. Soldering with infra-red light (IR-light) is one of the oldest and best known. Other common technologies are induction, hot air and contact soldering.

With the trend towards thinner cell material, laser soldering offers a considerable advantage over IR-light, as the energy required is not applied two-dimensionally to a surface but with pinpoint precision. This technology minimizes the amount of heat acting on the solar cell. The precisely controlled application of soldering energy provides great flexibility in a wide range of applications. For example, in addition to conventional cells, back-contact cells and other ribbon geometries can also be laser soldered.

Throughout the soldering process, a hold-down device developed specifically for this purpose by teamtechnik ensures the precise positioning and alignment of cell and ribbon.

One of the primary differences in

the system periphery is that this concept enables soldering only to be carried out at this stage and there is no additional handling. With the hold-down device, all the other processes can be done in parallel. This reduces costly processing time and a cycle time of three seconds can be accomplished throughout the machine.

What are the primary objective criteria for evaluating soldering quality? They are the pull-off force of the ribbon and the homogeneity of the soldered section. The pull-off forces are defined as the force required to peel the ribbon from the cell.

These forces should be at least 1N per millimeter width of the ribbon. The pulloff forces depend on the quality of the cell, the flux and the ribbon and how they are combined. The soldering result should ideally provide high pull-off forces with low cell tension. In addition, a homogeneous and consistent joint along the busbar is required. Stress causes faulty joints to crack open between the cell and the ribbon, reducing conductivity and current flow in the whole of the solar panel.

Figure 1. STRINGER TT by teamtechnik: optionally with IR-light or laser technology.

26 â&#x20AC;&#x201C; Global Solar Technology South East Asia â&#x20AC;&#x201C; Summer 2010

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Flexible non-contact laser soldering for solar cell strings

Figure 2. Laser process for more flexibility.

How does laser soldering work in detail? The laser beam generates energy that is applied with precision in order to melt the solder on the ribbon. The energy is concentrated into just a few millimeters, and moved precisely with a scanner throughout the area of the soldered joint.

A non-contact pyrometer constantly feeds back temperature readings in order to control the laser spot precisely. The laser then serially scans the busbar and accurately solders the ribbon to the cell so as to achieve high geometrical quality in the length, straightness, cell gap, cell/ ribbon position and alignment.

The actual soldering process is

Figure 4. Pull-off force testing.

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Figure 3. Laser Technology: precise and contiguous soldering.

supported by multiple heat zones that pre-heat the cells from below and activate the flux. Each heat zone can be adjusted and controlled separately and the temperatures for preand post-soldering can be set precisely according to the cell-type.

Axel Riethmüller, manager of teamtechnik’s solar division, summarizes the primary advantages of laser-soldering: “Laser technology provides a very high level of flexibility for fine tuning in order to achieve the best possible soldering results on different material combinations and alloys. A machine is therefore not restricted to one cell type but can be used for different cell types and sizes.

The closed-loop process balances out variations in the

material to achieve stable and continuous soldering quality. When running different cell types on one and the same machine, there is no mechanical adjustment required to adapt the soldering to the different busbars. The adjustment is carried out via recipes only.”

Today, laser technology is still an expensive soldering method. Nevertheless, at teamtechnik’s customers’ request, approximately 50% of the stringers built by teamtechnik are equipped for laser soldering. One reason is undoubtedly that the flexibility of laser technology will allow more scope for dealing with the challenges that future materials might bring.

Teamtechnik also benefits from this technology and has successfully completed tests on 130 μm thick cells and unleaded ribbon.

Figure 5. Stringer machine assembly at teamtechnik.

Global Solar Technology South East Asia – Summer 2010 – 27

PV Standards at SEMI

PV Standards at SEMI James Amano, SEMI, San Jose, California, USA

The SEMI International Standards Program is well known for developing consensus standards for the semiconductor industry. Less well known, but now increasing in visibility, is the long SEMI history of developing PV Standards1.

The first SEMI Photovoltaic Standard, M6, Specification for Silicon Wafers for Use as Photovoltaic Solar Cells2, was published in 1981. While the end-user products are widely disparate, the silicon processing technology that enables the solar industry has many similarities to that of the semiconductor and FPD industries—enabling us to leverage innovation and solutions from these sister industries. In 2008, more silicon was consumed globally making solar panels than microchips, and forecasters expect this solar growth to continue for many years.

Keywords: Standards, Photovoltaic Manufacturing, Solar Manufacturing, SEMI

SEMI gathered together executives from the PV industry in September, 2006, to discuss where SEMI could contribute most to the growth of the PV industry.

One of the major elements mentioned by these executives was the need for industry standards at the manufacturing equipment and materials level. At that meeting, Dr. Heinz Ossenbrink, unit head, Renewable Energies of the European Commission Joint Research Center, said, “Standards in photovoltaic are essential for the industry in order to lower trade barriers and to reduce the cost of ownership for cell and module manufacturers of their production facilities. Both elements are key to reaching competitiveness of the photovoltaic industry in a global energy market.”

This meeting kick-started SEMI’s efforts to establish a Standards Committee to focus solely on PV; formation of a European Committee was approved in 2007. Of course, one of the key advantages that SEMI has to offer in the development of industry standards is our global coverage, as we have events, offices and staff in all major PV manufacturing regions.

Following the formation of the European Committee, a North American Committee was established later in 2007, and committees in Japan and Taiwan were approved in 2009. A PV Standards Working Group is

in the initial stages of formation in China, and India isn’t too far behind.

The SEMI PV Standards Committee published three standards in 2009: PV1 (Test Method for Measuring Trace Elements in Silicon Feedstock for Silicon Solar Cells), PV2 (Guide for PV Equipment Communication Interfaces), and PV3 (Guide for High Purity Water Used in Photovoltaic Cell Processing). Over 25 other ballots are now under development for additional standards. But note that SEMI developed Standards for PV prior to the formation of an official PV-specific committee. Several test methods for are used by the industry, and SEMI F47 (Specification for Semiconductor Processing Equipment Voltage Sag Immunity) is increasingly being adopted by PV manufacturers in their production facilities.

One of the new SEMI standards efforts focuses on PV wafer and cell carriers, as automated material-handling equipment for PV wafers and cells is a prerequisite for an efficient PV fab. In reality, however, PV manufacturers and equipment suppliers have invested significant time and effort on material handling within their own production lines, distracting resources from maintaining focusing on core competencies where they can pursue innovation. This new effort, led by Q-Cells, will also enable

SEMI®: A Global Trade Association SEMI delivers access to: • Information • Global Markets • People—from governments to customers

SEMI maintains offices in Austin, Bangalore, Beijing, Berlin, Brussels, Grenoble, Hsinchu, Moscow, San Jose, Seoul, Shanghai, Singapore, Tokyo, and Washington, D.C.

SEMI activities include: • International Standards • Market research & statistics • Public policy • Environmental, health & safety • Industry collaboration and promotion • Expositions & conferences

28 – Global Solar Technology South East Asia – Summer 2010

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PV Standards at SEMI

standardization of equipment load ports and transport systems, resulting in both direct and indirect cost savings throughout the whole supply chain, less risk during ramp-up, and less effort for integration of the production line.

Approximately 30 percent of SEMI member companies are active in photovoltaic, and recently executives from PVindustry heavyweights Q-Cells and Suntech joined the SEMI International board of directors. Both Q-Cells and Suntech are engaged in the SEMI Standards Program, with their employees joining the over 400 technical experts currently at work developing Standards in over 10 task forces (TFs). These TFs, led by industry veterans, include factory automation (both software and hardware), silicon feedstock, test methods, cell specifications, and gases and chemicals. It is clear to these industry leaders that standards have been a key to success in the highly innovative semiconductor industry from the beginning, as they help eliminate variability in pro-

“Standards in photovoltaic are essential for the industry in order to lower trade barriers and to reduce the cost of ownership for cell and module manufacturers of their production facilities.” cesses to allow companies to focus on innovation. Reducing the number of options in a process to the most significant values allows companies to move faster in new areas of optimization, and as such, standards help improve process controllability.

SEMI International Standards Committee

Europe PV Committee

North America PV Committee

Japan PV Committee

Taiwan PV Committee

Int’l PV Analytical Test Methods TF

Int’l PV Analytical Test Methods TF

PV Equipment Interface Spec TF

c-Si Cell Appearance TF

PV Equipment Interface Spec TF

PV Gas, Liquid, Chemicals & Water TF

Japan PV Materials TF

Vibration Test Method TF

PV Materials (Connector Ribbon) TF

PV Electrical & Optical Properties TF

PV Silicon Materials TF

PV Materials TF

PV Transport Carrier TF

PV Carrier TF

PV Automation Coordination WG

PV Facilities TF

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Equipment Interface Stds Coordination WG

Cell Specification Coordination WG

Although it is difficult to get companies to release specific financial information on the benefits of Standards, their value can be seen by looking at the companies driving our major efforts. Q-Cells is leading the effort to standardize transport carriers and was involved in the Task Force that developed the PV2 Standard, along with Centrotherm, Deutsche Cell, Fraunhofer, ib-vogt, Manz Automation, Oerlikon, Roth & Rau, Schott Solar, SolarWorld, and many others. On the materials side, major companies such as Dow Corning, Elkem Solar, Hemlock, PV Crystalox Solar Silicon, Wacker Chemie, REC, Siliken and Sunicon are working on a silicon feedstock document.

While all ballots are voted on by the global SEMI Standards membership, different regions obviously have areas of regional priority. Both Japan and Europe are focused on PV materials and PV automation, North America is heavily involved in materials and test methods and Taiwan is working on standards for cell and module manufacturing.

Momentum is building for the development and widespread adoption of standards in the solar photovoltaic manufacturing industry. Defining future standards development efforts has been a constant challenge as companies collaborate in a pre-competitive environment to define the best path to foster innovation and market growth. Companies that actively participate in the development process will have access to the most current information available, and more importantly, these companies will shape the development of the industry and their role in it. To learn more, please visit www.semi.org/standards and www. pvgroup.org/standards.

References 1. http://pvgroup.org/Standards/index. htm 2. http://dom.semi.org/downloads.nsf/st andard?openform&did=EEE1C7DE04 ACE00A882574D30047F34A&sid=0

James Amano is director, international standards, for SEMI. He can be contacted at jamano@semi.org.

TF - Task Force WG - Working Group

Global Solar Technology South East Asia – Summer 2010 – 29

Improving the commercial viability of concentrator lens technology

Improving the commercial viability of concentrator lens technology Laurence Hayward, VentureLab Inc., Northbrook, IL, USA In this article, we will discuss manufacturing technology in the context of the CPV solar segment and the use of concentrating optics, but some of these same technologies can be applied to other segments including the use of Fresnel mirrors in CSP.

Keywords: CPV, Fresnel Mirrors, III-V Cells, Concentrating Optics

According to the 2009 Global PV Industry ments from the III and V columns of the Report, demand for solar energy has grown periodic table, such as gallium indium arapproximately 30% annually for the past senide, gallium indium phosphide and ger15 years. Still, solar energy contributes manium. Using multiple layers of different less than 1% to the world’s energy supply. elements increases the range of acceptable The ongoing challenge for commercialwavelengths of absorption for the cells and izing solar technology is cost. Although allows them to capture more energy from increased supply has reduced silicon prices, sunlight. A challenge with multi-junction total costs, including materials, component cells, however, is that they are considerably assembly, installation, and ongoing maintemore expensive than conventional silicon nance, remain high. The upfront nature of cells, further exacerbating the issue of cost. the capital expense is a challenge. The footHowever, there is potential to imprint requirement can be a limitation. And prove the efficiency-to-cost ratio by using except in select areas, conversion efficiency multi-junction cells in combination with isn’t at the levels yet desired. Without concentrating optics to focus sunlight subsidies, adoption will be protracted. onto a relatively small area of solar cells. In Not to be deterred, solar companies are simple terms, optical devices of area x are tackling the aforementioned challenges. used to harness sunlight and focus them One critical element in doing so is to onto a smaller area y of semiconductor find better methods of manufacture. The material with a concentration ratio is x/y. industry requires processes that can not Properly designed, CPV may require only only produce solar components to exacting hundredths of a fraction of semiconductor demands but also processes that scale up ef- materials compared to traditional PV cells, ficiently as production needs rise—all while paving the way for lower cost solar modules reducing costs. that consist mostly of relatively inexpensive Companies using concentrator technol- mirrors or lenses. Costs decrease as concenogy, both the concentrator photovoltaic tration ratios increase. Current technology (CPV) and concentrator solar power (CSP) is able to achieve concentrations of more companies, continue to achieve new rethan 1,000 times. cords of conversion efficiency. Several comThere are three main types of solar Figure 1 – Radial Fresnel Lens panies or institutions in CPV now claim efficiencies greater than 40%. However, it is one thing to achieve a high conversion efficiency, it’s yet another to create economic efficiency.

Among other things, the latter requires practical manufacturing technology.

In CPV, the emerging standard is the III-V cell, which Figure 1. Radial Fresnel lens. is comprised of ele-

30 – Global Solar Technology South East Asia – Summer 2010

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Figure 2Improving the commercial viability of concentrator lens technology Artist Rendition of Continuous Roll Processing

concentrators used. They include:

has more than 30 years of experience demonstrating the weathering capability of polymers used to reflect light on traffic signs. These products use Polymethyl methacrylate (PMMA), a transparent thermoplastic also known as “acrylic.”

Several of the longest running CPV installations have also used PMMA. However, it is important to note that there are many formulations of PMMA and selecting the correct form can be critical to long term performance.

This is an area where Robert Pricone, founder of 10x Technology, has a great deal of experience. According to Mr. Pricone, “The solar industry stands to benefit from the ground paved by other industries in the use of polymers that can hold up to the demands of high stress environmental conditions. Polymer selection, in combination with the method of forming the optics, is a key element in designing lens that efficiently transmit light for many years.”

Robert is the founder of an emerging company based in Libertyville, IL, that uses a continuous roll-to-roll manufacturing process to produce micro-structured polymer substrates. The process enables the production solar concentrator lenses in thin films, which can then be laminated to thicker substrates—the objective of which is to permit high volume manufacturing and lower the per square foot cost of concentrator lenses. 10x is not working alone; it recently formed a partnership with Evonik, a global supplier of specialty chemicals that supplies structural plastics for use in solar panels. The companies are marketing concentrator lenses using 10x micro-replication technology and Evonik Plexiglass. 10x is also collaborating with LPI, a world leader in the field of nonimaging optics, to develop the optical components.

Concentrator technology is an important element in the advancement of solar. While companies are taking different approaches to achieve new breakthroughs, a common need is a manufacturing platform that increases efficiency, reliability and cost-competitiveness.

Help appears to be on the way.

1. Reflective concentrators—using curved mirrors to focus sunlight on a parabolic or dish reflector. These mirrors are typically made from coated glass or metal foils.

2. Refractive concentrators—using Fresnel lenses to improve the performance of solar systems by concentrating the maximum level of sunlight on the PV cells. The structure of the lens varies by appli Figure 2. Artist rendition of continuous roll processing. cation and can be plane, cylindrical or dome shaped. They are typically process that results in many individual made from glass or polymer.

3. Hybrid concentrators—Fresnel lenses are of- parts or pieces that require handling and assembly. ten incorporated with supporting elements The use of thin films is emerging as an using refraction or total internal reflection. economical method of production. They The compound parabolic concentrator use less material, have a thinner active area, is one example. It has a wide acceptance and are well-suited for large-scale autoangle that can capture a relatively large mated production and packaging. Manuamount of sunlight without the need for factures of solar systems often purchase complex structures and tracking systems, “mirror film” from suppliers and attach it although they still might be used in conto parabolic or dish systems. junction.

For Fresnel lenses, one method is to Tracking systems are an important mold optically clear silicone rubber, which component to concentrator technology has thermal stability at high temperato ensure the focus of the sun meets the tures, and laminate it to a glass substrate. acceptance angle of the optics. At low However, weight and cost can be an issue concentrations (less than 500 times), a onein some applications and there are limited axis tracking system may be sufficient. At long-term studies demonstrating the weathhigher concentrations, a two-axis tracking ering of silicone adhered to glass. Another system is more typical to ensure maximum option is to use a selection of polymers exposure to sunlight. When supporting with a demonstrated history of holding up systems such as the parabolic concentrator under environmental stresses of the natumentioned above are used, the requireral elements. The traffic control industry ments for tracking system accuracy and complexity can be less demanding.

For both reflective and refractive concentrators, one of the major challenges is how to structure the optics into the solar panel. Injection or compression molding lenses of any material can result in long-term problems due to the polymers used and the residual stress inherent in these processes, which can lead to optical distortions over time. These processes also may have trouble meeting the tolerances required for precision optics and holding such tolerances over long periods of time under severe environmental stress.

Another challenge is developing efficient production technologies to bring down costs.

Injection molding is challenged by two factors: relatively high onFigure 3. CPV power plant in Puertollano, Spain. [Source: Concentrix Solar] going tooling costs and a batch

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Global Solar Technology South East Asia – Summer 2010 – 31

SOLARCON India 2010 Preview

SOLARCON India 2010 SEMI, the global industry association serving the manufacturing supply chains for the microelectronic, display and photovoltaic industries, launched the first SOLARCON SOLARCON India India—the country’s first focused trade show for the solar/PV industry—in Hyderabad last 2010 takes place 28-30 year. The three-day exhibition and conference was held at HICC in the backdrop of the impending announcement of the Cabinet’s approval for the much awaited National Solar July at the Hyderabad Mission.

International Conference The key highlight of the event was the keynote address by Prof. Eicke R. Webber, director, Fraunhofer Institute of Solar Energy Systems of Germany. On his maiden visit Center in Hyderabad, to India, Prof. Webber had been bestowed with “FABCity Excellence Award 2009”, which India. is instituted by FABCity SPV, Govt. of Andhra Pradesh in recognition of his outstanding services in the fields of solar energy and semiconductor industry. Another remarkable achievement of the inaugural SOLARCON India show was the attendance of very high quality business visitors, some of whom were from the board-level of large global companies. There were multiple announcements made on the sidelines of the event, including Govt. of Andhra Pradesh’s announcement of a “Solar City,” the signing of an MoU between Fraunhofer ISE and the University of Hyderabad KIP and a policy at the state level building on the National Solar Mission.

In fact, the inaugural edition had exceeded SEMI’s expectations, which was pleased with the response from all the stakeholders to SOLARCON India 2009.

Debasish Choudhury, Asia Pacific editor of Global Solar Technology magazine, had a chat with Sathya Prasad, President, SEMI India, to find out the learning and inputs provided by the platform and how they had imbibed it in this year’s SOLARCON India 2010 show. participation from the India PV companies Later this month, SEMI India is holding the second edition of its solar trade show in Hyderabad. What will be the composition of the exhibitors this year?

We have an expanded mix of industry players exhibiting at SOLARCON India this time. This includes: PV Material Suppliers, Manufacturing equipment suppliers, Solar Cell and module manufacturers, Inverter manufacturers, System integrators and suppliers, Electrical BOS suppliers, Mechanical BOS suppliers, Lighting companies, Project Developers, Design consultants, Testing and certifying bodies, etc

SOLARCON India 2009 emerged as the largest solar focused trade show in India on its debut edition. According to you, what set ‘SOLARCON India’ show apart from other renewable energy trade shows in the country?

Our singular focus on solar and the PV manufacturing supply chain enabled us to establish the SOLARCON India as India’s largest solar focused tradeshow. SEMI as an industry association also has a rich legacy of 40 years in conducting industry oriented tradeshows across the globe and we were able to leverage this experience in India successfully. Finally, our success is in large part due to the tremendous support and

Tell us about the three-day power-packed conference that will be held concurrently with SOLARCON India 2010 exhibition.

Who is going to present the Keynote Address this year?

The three-day conference at SOLARCON India 2010, as last year, will bring together leading global experts on solar/PV technology, business, applications, user perspectives, policy & finance. There are main Keynote Addresses on July 28 is by Dr. Winfried Hoffmann, President of European Photovoltaic Industry Association and solar Chief Technology Officer, Applied Materials. Besides this, we have various Technology Keynotes from eminent solar/PV executives from India and abroad.

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How are you encouraging exhibitors and visitors in order to generate business opportunities at SOLARCON India 2010 exhibition?

There are several innovative things we are bringing to the exposition this year to add further value to the exhibitors and visitors.

For exhibitors, we are sending customized visitor flyers, providing media exposure through newsprint and event directory advertisement etc. For visitors, we offer the best ambience for B2B interaction, free internet, etc.

What do you think delegates, visitors and exhibitors should look forward to as they prepare to participate in SOLARCON India 2010?

We are working hard to deliver all the various elements needed to make this event a success from a delegate, visitor and exhibitor perspective. We believe that having key global and India PV Industry players (from across the value chain), Policy experts, senior Govt officials, Finance community, project developers, etc will bring together various stakeholders and entrepreneurs on a single platform to discuss and debate various challenges and opportunities in increasing the market penetration of solar/PV in India.

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Flexible Flexible silver silver paste paste enables enables thin-Film thin-Film photovoltaic photovoltaic Flex Flex solar solar cells cells

Soni Saran Singh Interview Inside

advanced advanced screen screen printable printable thin thin Film Film pv pv silver silver conductor conductor compositions compositions

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‘printing’ ‘printing’ pv pv electrodes electrodes onto onto Flexible Flexible substrates substrates

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INDUSTRY NEWS INTERNATIONAL DIARY

GSP2.10

New Products

New products robust and features a special damping system that decouples the printing table from the outer frame and avoids the transmission of vibration.

Development is not at an end yet.

The next step is already targeted, which is another reduction of the printable structures down to 25 µm. This will bring screen printing into an area of applications that until now have required expensive offset or flex print technologies. www.essemtec.com New dry screw technology pump series DRYVAC for solar industry

Micro structures with nano pastes 50 µm wide conductive lines can now be screen printed due to nano pastes and a new printing process, which is implemented in Essemtec’s new SP900-S printer. This system surpasses the capabilities of expensive offset or flex printers because screen printing is inexpensive, flexible and allows the printing of very high thickness layers.

Conductor lines with widths from 100 to 150 µm and a height of approximately 12 µm have been state of the art for a long time when using screen and stencil printers. However, Essemtec’s SP900-S can print structures that are only 50 µm in width and 40 µm or more in height.

The PV Lab in EPFL Neuchâtel uses the SP900-S to produce its heterojunction solar cells.

The efficiency of many products depends on the optimal design of the conductors, as do solar cells. The traces

on these cells are called bus bars and fingers. They should be as thin as possible to maximize the active area. The cross section also should be as big as possible to minimize the inner resistance of the cell. Using the SP900-S, solar cell manufacturers can maximize the height/ width ratio of the conducting traces. No other printing machine allows such a high layer thickness to be produced and such high cross sections to be achieved. This is advantageous not only in the solar industry but also in other products that require thin lines with high electrical current capacity.

Narrow but high traces can be produced by printing multiple layers on top of each other until the desired height is reached. The idea is not new, but until now almost no one could print such thin lines so precisely on top of each other. The SP900-S has been optimized for this task.

The SP900-S is designed especially

34 – Global Solar Technology South East Asia – Summer 2010

Oerlikon Leybold Vacuum presents the new dry screw technology pump series, DRYVAC, which can save up to $3,500 per year compared to similar pumps with identical suction volume, depending on operating parameters. This helps the producers of thin film silicon solar modules to lower operating costs and increase their profits.

These pumps are ideal for demanding load lock applications and are resistant against dust, vapors and particles. They effectively pump light gases, but also toxic and corrosive gases such as NF3 gases used in the solar industry to flush coating chambers.

Relevant pump parameters of the DRYVAC can be visualized during operation via a touch screen monitor. The “i”-variants with integrated self-control can communicate via data exchange between pump and plant controls using various interfaces. Of course, the touch-panel can also be used. For pump control, there are multiple sensors such as temperature control with warning functions, and a pressure sensor for monitoring the exhaust

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New Products

pressure. Moreover, the data of the integrated frequency converter can also be visualized. www.oerlikon.com New ROFIN PowerLine L Series for high-speed micro material processing

With its new PowerLine L series, ROFIN introduces q-switched solid state lasers specifically designed for micro material processing applications which require high average power and high pulse energy.

Examples are thin film removal on glass and flexible materials, ablation of dielectric layers, silicon processing, drilling and cutting.

In the 1064 nm class, the PowerLine L 300 completes ROFIN‘s laser range for edge deletion applications. Whereas ROFIN‘s DQ series offers 500 to 1000 watts, the PowerLine L 300 features more than 200 W laser power at 10 KHz and smaller optical fibers, especially an optimized square fiber with 400 μm diameter.

Compared to round fibers, square fibers provide highest efficiency by machining a bigger area per pulse. Selective

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opening of dielectric layers and direct laser doping currently draw a lot of interest in crystalline solar cell manufacturing. For both applications the frequency-doubled PowerLine L 100 SHG already proved its perfect applicability in various research projects. The laser source offers optimum beam characteristics and sufficient power for large production scale. Green lasers with 532 nm show the desired near-surface absorption in silicon and can be equipped a wide range of long-living optical components and fibers. With optimized fibers, a top-hat beam profile can be realized which provides homogenous energy distribution within the entire laser spot area. www.rofin.com New photovoltaic encapsulant helps deliver more power at lower cost Oerlikon Solar and DuPont have collaborated on a new thin white reflective solar PV encapsulant sheet, called DuPont™ PV5223. This latest addition to the DuPont™ PV5200 Series of PVB sheets enables easier manufacturing of next-generation thin film PV modules that not only capture sunlight coming in, but also reflect more sunlight back through the module’s active layer, thus capturing an extra zap from every available ray of light.

DuPont materials research, guided by Oerlikon thin film manufacturing knowhow, produced the DuPont™ PV5223 white reflective encapsulant sheet for use in Oerlikon multi-stack laminating processes. The DuPont™ PV5223 white reflective encapsulant is placed on the back (non-sun-facing) side of Oerlikon Solar’s specially developed thin film coatings. By making a white reflective encapsulant, DuPont helps Oerlikon Solar eliminate the need for reflective paint.

Designed for use with Oerlikon Solar’s Micromorph® technology, DuPont’s new PV5223 white encapsulant increases light

reflectivity by more than 50% versus paint, to an almost perfect 94% reflectivity.

What’s more, the added reflectivity comes in a super-thin 0.45-mm sheet well suited for Oerlikon Solar’s low-topology module design. The sheet is more than 40% lighter in weight than traditional 0.76-mm PVB encapsulants.

Tests conducted by Oerlikon Solar and DuPont show excellent retention of the 0.45-mm encapsulant’s performance properties after 1000 hours of damp heat aging. The white PVB sheet delivers stronger adhesion than clear PVB sheet materials, which translates into tougher, longer-life modules. www.oerlikon.com/solar Polyurethane resin system for electrical potting of solar power inverters Power inverters contain highly sensitive electronics, e.g. transformers, restrictors and e-filters, which are protected best by a corresponding casting resin. The casting resin protects the electronics against environmental influences and simultaneously providing heat dissipation with noise insulation.

WEVO-CHEMIE, a polyurethane resin formulator of casting resin systems used by many European manufacturers offers two exceptional casting resin systems for solar power inverters. PU 403 FL features longterm heat resistance up to 160°C, and PU 552 FL offers long-term heat resistance up to 130°C. Both resin systems have UL-94 (V-0) accreditation (UL file no. E108835), offer a high thermal shock resistance, are long lasting, and provide good acoustical attenuation at a very competitive cost. For more information e-mail mrideep@vsnl.com or info@wevo-chemie.de.

Global Solar Technology South East Asia – Summer 2010 – 35

Industry News

Industry News— continued from page 8

situated in the state of Karnataka in the future. With the erection of the power plant, now over 80% of the residents in and around Itnal have access to reliable and affordable energy—not just in their households but above all on their farms.

SunTechnics erected the megawatt-class photovoltaic plant upon the order of the local utility KPCL. On 17.3 acres, 13,000 solar modules supply over 4,000 megawatt hours of clean energy into the local grid a year. www.suntechnics.com/in Astonfield and Belectric team up to realize 5 MW solar power plant in Rajasthan Astonfield Renewable Resources and Belectric entered into an agreement for the execution of Astonfield’s 5 MW solar power plant in Osiyan, Rajasthan. The Osiyan project is one of several Astonfield plants expected to be approved under the Migration Phase of the Jawaharlal Nehru National Solar Mission and will be Astonfield’s first solar power plant to be commissioned and come online in FY2010-11. Belectric has already completed site designs and engineering on the plant.

The 5MW solar power plant located in the Jodhpur District of Rajasthan will sit on 30 acres of land. A total of 185 acres has been secured under a long term lease to allow for an additional 20MW build out in the future. The Osiyan plant is expected to bring over a hundred jobs to the local community and has the capacity to power approximately 13,000 homes. www.belectric.com, www.astonfield.com REC signs Singapore’s largest solar supplier agreement to date with Housing Development Board REC successfully won the 1 MW tender to supply PV panels for residential rooftop installations for HDB homes in six precincts against 13 other companies. This is currently the largest single solar panel procurement agreement Singapore has ever completed and will translate into PV panel installations for about 25 housing blocks covering 1.5 times the size of a football field. This is part of HDB’s solar capability building program which aims to build up expertise in solar energy generation, to achieve proficiency in design and installation, as well as cost-effectiveness and enhanced maintainability. Installation of the REC Peak Energy Series modules will begin in the fourth quarter of 2010. REC has developed one of the world’s most inte-

grated and automated solar energy manufacturing sites in Singapore. Approximately 1300 people are working at the site which will reach full production capacity of 740 MW for wafers, 550 MW for cells and 590 MW for modules by 2012. www.recgroup.com Bangkok Solar Power Co. signs a strategic investment agreement with Prime Sun Power Inc. Prime Sun Power Inc. entered into a strategic investment agreement with Bangkok Solar Power Co., Ltd. (BSP) to acquire up to 6,639,063 shares of PSP common stock at price of €7.73 per share.

All shares issued to BSP will be subject to a lock-up period until December 31, 2013. The two companies have agreed to work together in a strategic alliance whereby BSP shall be appointed as the general contractor to perform the EPCI contract for PSP solar power plants for at least 50 megawatts peak per annum until 2013. BSP will purchase the PSP shares in increments of €400,000 upon activation of each megawatt peak of solar power to be covered by the EPCI service agreement. If all of strategic alliance shares are acquired, BSP will own 14.2% of PSP’s issued and outstanding shares of common stock. www.bangkoksolar.com, www.primesunpower.com Moser Baer Photo Voltaic forays into Australian market Moser Baer Photo Voltaic Ltd (MBPV) will now offer its crystalline silicon products to the Australian consumers.

Recognizing the TuV Intercert’s IECEECB certification, Clean Energy Council (CEC) has allowed the company to offer its crystalline silicon modules in Australia.

The certification has been accorded

by TuV Intercert recognizing the high quality of these products which adhere to top global standards and benchmarks.

This certification is mandatory for all those players who want to operate in the Australian market. www.moserbaerpv.in IIT Bombay and Applied Materials to collaborate on renewable energy Indian Institute of Technology Bombay and Applied Materials, Inc., broadened the scope of their ongoing research collaboration to develop new energyrelated initiatives. As part of this collaboration, Applied Materials will donate three process chambers to IIT Bombay for depositing thin films on solar cells using physical vapor deposition (PVD) and chemical vapor deposition (CVD)

36 – Global Solar Technology South East Asia – Summer 2010

technologies. Applied Materials will also work with IIT Bombay research teams to set up a wet chemistry laboratory for developing new materials.

These materials will be used for a variety of renewable energy-focused applications, including the fabrication of next-generation solar cells. As a symbolic representation of its commitment to clean technology and a sustainable future, Applied Materials will also donate a solar panel system to IIT Bombay. The panels will be connected to energy-efficient LEDs that will light the University’s main avenue.

IIT Bombay was specifically mentioned in the Jawaharlal Nehru National Solar Mission as a location for the National Centre for Photovoltaic Research & Education. This honor recognizes IIT Bombay’s contributions over the years in establishing collaborative relationships and initiatives with industry. This new alliance with Applied Materials extends the Institute’s mission of setting up this National Centre. www.appliedmaterials.com Aditya Solar Power strikes USD 545 million deal with UAE firm UAE-based company Mulk Holding has announced an agreement with Bangalorebased Aditya Solar Power Industries to develop a 200 megawatt solar thermal project in the UAE. The holding company said one of its subsidiaries, Mulk Renewable Energy, will supply and install solar thermal power plants for Aditya Solar in a deal valued at 2 billion dirhams (USD 545 million). According to the agreement, Mulk Renewable Energy will create a joint venture with Aditya Solar to develop the project. Mulk Holding has invested 5 million dirhams in research and development of solar plants and expects a 500 million-dirham revenue from the first year of operation of the power plant.

Common Wealth Games 2010 to be ‘solar powered’ by Reliance RIL Solar Group, the solar energy initiative of Reliance Industries Ltd. (RIL), has successfully implemented and commissioned India’s first 1 MW solar plant on the roof of a stadium in New Delhi. The Thyagaraj Stadium, developed by the Government of Delhi, is planned to be a model green stadium and will host Netball in the upcoming Common Wealth Games 2010. The company has also implemented power plants in the R K Khanna Tennis Complex as also solar LED street lights and garden lights in the Commonwealth Games Village. RIL Solar

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Industry News

Group installed and commissioned the 1MW solar plant in a record duration of less than 3 months. The power plant is expected to generate around 1.4 million units of electricity per year. www.relsolar.com Indian solar photovoltaic technology make inroads into Canada In a rare and remarkable first, Indian technology to make solar photovoltaic (SPV) panels is going to be utilized in a developed country. Solar Source Corp (SSC), a Canadian renewable energy holding company, announced a joint venture with Bangalore-based Hind High Vacuum Company Pvt. Ltd. (HHV) to build Canada’s first amorphous silicon solar panel manufacturing plant based on technology and equipment developed by HHV. The facility, to be set up by SSC’s wholly owned subsidiary, Solar Source PEI, will be located in summer side, Prince Edward Island (PEI) near the eastern seaboard of Canada. The proposed annual capacity is 120 MW, to be established in four phases, with Phase One slated to reach 30 MW of capacity. The plant will make panels for the building-integrated, ground-mount and commercial rooftop markets. Besides the above thin film solar panel making facility, the JV MoU also includes a proposal to build in four phases a 120 MW crystalline silicon solar panel manufacturing facility in Ontario. www.hindhivac.com Solar Mission all set to take off!— continued from page 4

solar industry in India to work with along side international research institutes and corporations.

At the global level, the year 2010 is going to be different from the gold rush years of 2008 and 2009 when Spain and Germany respectively accounted for most of the solar installations. Between 2000 and 2009 global PV demand grew at an average rate of 51% rising from 170 MW to 7118 MW. Traditionally, generous and growing European FITs enabled global demand to grow rapidly outstripping supply and leading to increase in feedstock prices as well as attracting new entrants into the solar industry but in 2008 and 2009 market power has gone into the hands of power project developers and financiers. Still today, global manufacturing capacity greatly exceeds global demand. By the end of 2010 some 16.1 GM of module manufacturing capacity will come online whereas the demand is expected to be between 11,218 MW (according to GTM research) and 13.1 GW in 2010 (according to iSuppli). This will continue to exert pressure on average selling prices which will bring further discomfiture for the solar manufacturers. The good news is that lower prices will eventually mean a larger market size going forward.

joint World Conference of:

Mr Subramanya has been associated with Tata BP Solar since its inception. He was appointed chief executive officer of the company in 2006.

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Global Solar Technology South East Asia – Summer 2010 – 37

Association News Title

Assocation News SEMI India unveils recommended best practices for solar feed-intariffs (FIT) SEMI India’s PV Group organized a panel discussion in Bangalore today, to discuss its public policy principles on feed-in tariffs and their relevance to the Jawaharlal Nehru National Solar Mission (JN NSM).

A SEMI/PV Group white paper on policy principles and recommended global best practices for solar feed-in tariffs, titled “Advancing a sustainable Solar Future,” along with comments on its relevance to the Indian context were unveiled on this occasion. The focus of the white paper is on best practices that would enhance feedin-tariffs (FITs) as a mechanism to advance solar energy in markets. FIT is currently now in practice in over 30 countries and has been present for over 20 years in mature PV markets. FIT is also an effective and versatile mechanism and can be successfully integrated with any country’s existing policies.

The best practices and characteristics of FITs outlined in the white paper include, support for technology differentiation, setting of generation cost-based rates, fair purchase & interconnection requirements, use of fixed price & long term payments and the use of predictable incentive declines.

Sathya Prasad, president SEMI India, was joined by prominent solar industry leaders including K. Subramanya, CEO, Tata BP Solar & chair SEMI India PV Advisory Committee, and Dr. J Gururaja, honorary executive president, REAF (Renewable Energy Advocacy Forum), on the panel with K Subramanya as the chairperson. The session aimed at raising awareness about the relevance of global best practices on feed-in-tariffs for promoting Solar/PV expansion in the country, also addressed results of a global survey of FIT policies, drawing of comparisons between the global survey and recommended FIT practices, key comparisons between the JN NSM and global FIT best practices, current status of the mission and the importance of its successful & effective implementation for the growth of solar/PV in India.

Setting the context, Sathya Prasad, president, SEMI India, stressed the role and importance of incorporating best practices of feed-in-tariffs for the growth

of the PV industry in the country. He said, “Our study suggests that the JN NSM aligns well with global Feed-in Tariff best practices and should therefore provide a good foundation for a flourishing solar/ PV market, manufacturing industry and job growth in India. With this landmark policy framework in place and the key role envisaged for solar in India’s energy future, the focus must now be to ensure the successful implementation of the mission.”

For more information, please visit www.semi.org or www.pvgroup.org.

India’s solar thermal industry comes together to float Solar Thermal Federation of India (STFI) The Indian 3.5 million m2 installed solar thermal industry has got a new voice and a platform called Solar Thermal Federation of India (STFI). STFI is a not-for-profit panIndian association comprising of leading solar thermal manufactures (largely being solar water heater (SWH) manufacturers registered under the Societies Registration Act (1860)). It has 14 charter members who are SWH manufacturers that control nearly 75% of the market and is headquartered in Delhi. K Subramanya, CEO, TATA-BP Solar, would be the chairman and Hemant Revankar, managing director, Bipin Engineers, would be the vice-chairman.

Jaideep Malaviya will steer the federation as its full time president. Senior executives of major players in the industry will play an active role in STFI in various capacities.

The key trigger which galvanized the industry to come together is the recently unveiled Jawaharlal Nehru National Solar

Mission, which has set a target of 20 million m2 by the year 2022 which has opened up the market besides creating challenges that need to be addressed in a cohesive and coherent manner by the

38 – Global Solar Technology South East Asia – Summer 2010

entire industry. Primary on the agenda of STFI is evolving an appropriate policy framework and user-friendly financing mechanism to make this target realizable by working in close coordination with the Ministry of New and Renewable Energy, Ministry of Power and Ministry of Urban Development. Another important focus would be to enhance the competitiveness of the Indian solar thermal industry through continuous investment in R&D besides market awareness/development.

Another priority would be to take the focus beyond solar water heating in terms of solar thermal applications to expand the market scope and horizons for constituent players.

One of the immediate action items of STFI would be to develop trained talent pool that is proficient in installation and maintenance through a launch of a common industry-accepted Certification program on a pan-India basis. A first of its kind certification program the initiative will address a key issue hindering end user confidence and allow trouble free usage for 25 years, which is the typical life of a solar water heater installation. To this end and also to achieve the priorities stated above, STFI will partner and closely work with associations and institutes (of relevance) that are regional, national and international.

SESI to organise ICORE 2010 in Chandigarh Solar Energy Society of India (SESI) is organizing its annual flagship event International Congress on Renewable Energy (ICORE)-2010 on 1-2 December 2010 at Hotel Mountview, Chandigarh.

The theme of ICORE-2010 is “Renewable Energy for Inclusive Growth”, since accelerated development and deployment of renewable energy will not only meet the power requirements of the country but also generate huge employment opportunities in rural areas. A trade show will also be held co-located with ICORE 2010 during 1-3 December 2010.

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PV + Solar Expo 2010 in Mumbai a runaway success The opportunities in the solar market are drawing a number of global companies to enter India though the time-tested trade show platform. Electronics Today’s PV + Solar India Expo 2010, the first international conference and exhibition of photovoltaic, solar thermal, solar architecture, photovoltaic equipment, products, materials and systems, reinforced the credence by attracting leading solar companies from China, Switzerland, Finland, Germany, Japan, Russia, Taiwan, USA and Czech Republic at the trade show and conference. With a total of 57 exhibitors, including 19 participants from overseas, the maiden PV + Solar Expo 2010 at World Trade Centre, Mumbai was a big draw during 4-6 March 2010. According to the organiser, the event drew over 4,000+ qualified visitors including a sizeable number from overseas as well.

PV + Solar India Expo 2010 was a joint initiative by the Solar Energy Society of India (SESI) and Electronics Today and was amply supported by the Ministry of New and Renewable Energy (MNRE), Government of India.

A range of solar products and systems were on display for domestic, on-grid and off-grid usages, LED lighting systems and solutions, and balance of systems, but very few large equipment and systems for solar manufacturing. Some of the leading Indian participants from the cell and module segment were TATA BP Solar, Indo Solar, Reliance Solar, Vikram Solar, Surana Ventures, Waree Energies & XL Telecom and Energy.

Amongst the global suppliers of equipment and systems for solar manufacturing, BWS GmbH, Schmid GmbH, ERSA Gmbh, Luvata Pori OY, Komax AG, KIC Inc., Monocrystal of Russia, Schunk Sonosystem GmbH, Sierra Therm Production Furnaces Inc.,

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and SVCS Process Innovation of Czech exhibited at the show. Giving them company were a number of manufacturers’ representatives led by Bergen Group, with the largest booth at the show, along with International Marketing Corporation, Bergen Systems and Komax Automation from India. Other notable Indian exhibitors at the show were Aplab, Avni Energy, HHV (Solar Div.), Hynetic Electronics, Sojitz India and Sumitron Exports. But the biggest crowd puller in the show was Suntech Power Holdings Co., Ltd. of China.

Suntech Power, the world’s largest producer of crystalline silicon solar panels, launched its Hi Performa PLUTO 205 Ade 195 Watt peak module at the show.

Pluto cells feature a unique texturing process that improves sunlight absorption, even in conditions of low and indirect light. According to the company, the patent-pending Pluto technology for crystalline silicon solar cells improves the power output by up to 12% compared to conventional production methods. Also, on display were STP 280 Vd module suitable for utility-scale and STP 185S24/Ad module suitable for residential market in the booth. In addition, Suntech prominently displayed its STP 080Ts-AA thin film amorphous silicon module in the booth—most suitable for residential roof-top systems, on-grid utility systems and commercial systems.

Along with the exhibition, Electronics Today had also organised a two-day international conference, “Jawaharlal Nehru National Solar Mission—The Road Ahead,” and two technical workshops in association with the Solar Energy Society of India (SESI). The concurrent workshop and two-day conference during 3-5 March was over-flowing with attendees, riding on the launch of National Solar Mission.

Delivering the inaugural address, Dr. Farooq Abdullah, Hon’ble Union Minister for New and Renewable Energy, who was also the chief guest said, “The Government of India has launched the Jawaharlal Nehru National Solar Mission with a twin objective—to contribute to India’s long term energy security as well as its ecological security. The Mission’s mandate is to establish India as a global leader in solar energy and to create an enabling policy framework for the deployment of 20 GW of solar power by 2022. In the first phase, 1300 MW power projects out of which 1,100 MW grid connected power and 200 MW for areas not connected to grid power like poor & backward areas and border areas will be implemented.” He also said that producing solar power is one part, but a good connectivity can only help deliver it to the grid. Manufacturing and R&D should preferably be indigenous.

He also added storing the solar energy in batteries at night is expensive. Indian companies should pursue R&D to devise cheaper methods. During the address, he made a strong pitch for solar thermal than PV technology, to make the solar mission technology neutral. After that, he had a one-to-one free-wheeling interaction with all the attendees and delegates at the conference.

On the whole, Electronics Today’s maiden effort in association with SESI created a credible platform for the growth of the solar eco-system in western India.

This prompted the organizers to begin the groundwork for next year’s edition, scheduled during April 19-21, 2011 at Bombay Exhibition Centre, Mumbai, which is a more modern and spacious venue for holding an international show.

So, we can expect to witness some cutting edge technology solutions at the next edition of the show.

Global Solar Technology South East Asia – Summer 2010 – 39

Events Calendar Title Industry News

Industry News

Events Calendar 28-30 July 2010 SOLARCON India Hyderabad, India www.solarconindia.org

14-16 October 2010 4th POWER Bangladesh 2010 Dhaka, Bangladesh pv-expo.net

2-4 November 2010 Clean Energy Expo Asia Singapore www.cleanenergyexpoasia.com

6-10 September 2010 25th European Photovoltaic Solar Energy Conference Valencia, Spain www.wip-munich.de

26-28 October 2010 PV Taiwan 2010 Taipei, Taiwan www.pvtaiwan.com

14-16 December 2010 Intersolar India Mumbai, India www.intersolar.in

27-29 October 2010 DIREC 2010 New Delhi, India direc2010.gov.in

16-18 February 2011 EXPO Solar/PV Korea 2011 Seoul, South Korea www.exposolar.org/2011

8-10 September 2010 SEMICON Taiwan Taipei, Taiwan www.semicontaiwan.org

Intersolar comes to India Intersolar India 2010 will take place for the first time at the Bombay Exhibition Centre in Mumbai December 14-16, 2010.

MMI India Pvt Ltd., a subsidiary of Messe München International, will organize India’s international exhibition for the solar industry.

Intersolar India will focus on the development of the Indian solar market as well as promoting targeted cooperation between industry, commerce, service providers and politics within this quickly developing market. The aim of the exhibition and conference is to encourage the growth of the Indian solar market and to drive forward global networking within the solar industry.

More than 200 exhibitors and 6,000 visitors expected. Along with the trade fair, a high profile conference will take place with participation from Indian and international solar professionals The organizers of the the world’s leading exhibition series for the solar industry strongly believe in the success of Intersolar India and the partnership with MMI India.

“The interest in Intersolar India is overwhelming,” says Markus Elsaesser,

CEO of Solar Promotion International (SPI). “Every day we get many requests from international and local companies, especially after the great success of the Indian PV session at the Intersolar Europe Conference in Munich in June. Solar professionals know that the Indian PV and solar thermal market is one of the most expanding markets within the next couple of years. No other country in the world has such a hugh potential for growth.”

Klaus Seilnacht, CEO of Freiburg Management und Marketing International GmbH (FMMI), says, “Thanks to its indepth industry-specific experience and its strong international network MMI India guarantees the most effective platform for the success of Intersolar India.”

“Through the cooperation between SPI, FMMI and MMI India, Intersolar India will establish itself as the leading exhibition in the growing solar industry,” says Thomas Loeffler, Deputy CEO, MMI India. “Complimenting this growth is the positive feedback from the industry. With MMI’s professional expertise for organizing B2B trade fairs, we are looking forward to a successful Intersolar India 2010”.

40 – Global Solar Technology South East Asia – Spring 2010

About Intersolar With over 2,600 exhibitors and 92,000+ visitors spanning three continents, Intersolar is the world’s leading exhibitionseries for the solar industry. Intersolar India is India’s international exhibition and conference for the solar industry and, as a leading industry platform, focuses on photovoltaics and solar thermal technology.

Following its successful launch in 2009, the event now takes place annually at the Bombay Exhibition Centre in Mumbai.

Intersolar India supports the development of the Indian solar market and promotes cooperation between key players from industry, commerce, service providers and politics.

Intersolar’s storied history of international exhibitions and conferences spans almost 20 years. Taking place in addition to Intersolar India are Intersolar North America in San Francisco and Intersolar China/SOLARCON China in Shanghai, launching in 2011. The world’s largest exhibition for the solar industry is Intersolar Europe in Munich.

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42 â&#x20AC;&#x201C; Global Solar Technology South East Asia â&#x20AC;&#x201C; Summer 2010

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