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The Global Journal for Solar and PV Manufacturing Professionals

Volume 3 Number 5 May 2010

Matt Holzmann Interview inside

A practical guide for improving crystalline solar cell efficiencies through firing process optimization

NEW PRODUCTS

Smart packages for CPV cell devices

INDUSTRY NEWS

Achieving thermal uniformity in photovoltaic applicationS Increasing solar panel production efficiencies with acrylic foam tape

INTERNATIONAL DIARY


June 9–11, 2010 The World´s Largest Exhibition for the Solar Industry New Munich Trade Fair Centre | Germany

1,800 Exhibitors 130,000 m2 Exhibition Area 60,000+ Visitors w w w. i n t e rs o l a r. d e


Contents

Global Solar Technology is distributed by controlled circulation to qualified personnel. For all others, subscriptions are available at a cost of £110/US $220/€165 for the current volume (6 issues).

Contents 2

Volume 3, Number 5 May 2010

Editorial Alan Rae

6

No part of this publication may be reproduced, stored in a retrieval system, transmitted in any form or by any means­—electronic, mechanical, photocopying, recording or otherwise— without the prior written consent of the publisher. No responsibility is accepted for the accuracy of information contained in the text, illustrations or advertisements. The opinions expressed in the articles are not necessarily those of the editors or publisher.

Technology Focus

© Trafalgar Publications Ltd.

30 Increasing solar panel production efficiencies with acrylic foam tape Rick Traver and Brent Ekiss, Fabrico

Designed and Published by Trafalgar Publications, Bournemouth, United Kingdom

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A practical guide for improving crystalline solar cell efficiencies through firing process optimization Bjorn Dahle, KIC

10 Smart packages for CPV cell devices Andy Longford, consultant, and Domenic Federici, Interplex Engineered Products

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13 Achieving thermal uniformity in photovoltaic applications Jake Lindley, Watlow 16 High-performance labels for the solar photovoltaic installation industry Lauren M. Catalano, Tyco Electronics Corporation

20

Special Features

20 Interview­—Matt Holzmann, Christopher Associates 22 Power with a purpose 24 SNEC PV—The Shanghai Show Regular Features

3 Industry News 18 Analyst Buzz 26 New Products Visit the website for more news & content: www.globalsolartechnology.com.

30

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Global Solar Technology – May 2010 – 1


Editorial

Editorial Offices

Europe Global Solar Technology Trafalgar Publications Ltd 8 Talbot Hill Road Bournemouth Dorset BH9 2JT, United Kingdom Tel: +44 7766 951665 news@globalsolartechnology.com www.globalsolartechnology.com United States Global Solar Technology PO Box 7579 Naples, FL 34102, USA Tel: (239) 245-9264 news@globalsolartechnology.com China Global Solar Technology Electronics Second Research Institute No.159, Hepin South Road Taiyuan City, PO Box 115, Shanxi, Province 030024, China Tel: +86 (351) 652 3813 Editor-in-Chief—Trevor Galbraith Mobile: +1 239 784-7208 editor@globalsolartechnology.com Managing Editor—Heather Lackey hglackey@globalsolartechnology.com Technical Editor—Dr. Alan Rae arae@globalsolartechnology.com Editor—Debasish Choudhury dchoudhury@globalsolartechnology.com Circulation and Subscriptions Tel: +1 (239) 245-9264 subscriptions@globalsolartechnology.com

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Dr. Alan Rae

Technical Editor, Global Solar Technology

A new photovoltaic industry association forms A sign that our industry is coming of age is the proposed formation of a new association to serve professionals in the solar PV field. Associations of this kind can bring real value—for example in the electronics industry, SMTA and IMAPS really benefit both companies and individuals with their national meetings, local chapters and education programs. This organization has the potential to do the same for photovoltaic specialists. Matthew Holzmann, president of Christopher Associates Inc., said, “The photovoltaic industry is moving fast. We are all pushing hard. There are few professional resources out there for the engineering and manufacturing community on an individual basis. We have tradeshows and some standards work being done, but engineering education, technology benchmarking and other professional issues and opportunities must be addressed as well. Hopefully we can begin a dialog to meet this need.” In order to facilitate the discussion, Flextronics Corporation has offered to host a formational meeting for such an organization. The meeting is open to all, and will be held on June 10, 2010 from 5:30-7 p.m. at the following location: Flextronics Corporation Building #1 Milpitas Conference Room 637 Gibraltar Court Milpitas, CA 95035 Contact: Dennis Willie

to the 2005 USGS survey (Circular 1344), 49% of water is used in thermoelectric power generation—even higher than irrigation at 31%. With current concerns over climate change and the increasing rate of water consumption worldwide, there are widespread shortages predicted. The US Government Accountability Office predicts that by 2013, 36 states in the USA—more than half the country—expect water shortages. Solar PV not only offers a way to power water treatment systems on a distributed basis, but using solar rather than thermoelectric power will lead to huge water usage savings also. This Issue We have a really interesting set of articles for you this month. Our contributors cover ways of improving production efficiency, device efficiency and durability—and a timely discussion of the role of solar PV in providing fresh water.

—Alan Rae, PhD

Save Water—Go Solar! A recent pair of articles in the New York Times by Erica Gies (“Water Adds New Constraints to Power” and “Turning To Water Conversion to Save Energy”) caught my eye, and I did a little digging. The collecting, treating, distribution and use of water consumes a surprising amount of energy—7% worldwide, 13% in the USA overall and 19% in California. What’s also surprising is how we use water. According

Asia/Pacific Print - Debasish Choudhury Tel: +91 120 6453260 dchoudhury@globalsolartechnology.com 2 – Global Solar Technology – May 2010

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invest future in your

First Solar Manufacturing, Frankfurt, Germany (top)—featured in Global Solar Technology issue 2.2, Mar/Apr 2009.

What’s in a year’s worth of Global Solar Technology? Leading-edge technical articles, insightful columns, the latest technological developments, manufacturing equipment and products, industry news, industry event coverage, market rundowns and much more.

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Volume 1 Number 2 November/December 2008

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Global Solar Technology Volume 1 Number 2

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News for Solar Manufacturing Industry

News for Solar Manufacturing Industry

Volume 2 Number 1 Jan/Feb 2009

Paul Davis Interview Inside

MATERIALS AND THE GROWTH OF PV TECHNOLOGY COMBATING THE IMPACT OF CONTAMINATION IN SOLAR CELL PRODUCTION

FLEXIBLE SILVER PASTE ENABLES THIN-FILM PHOTOVOLTAIC FLEX SOLAR CELLS

NEW PRODUCTS

CONVERTING CONSIDERATIONS FOR FLEXIBLE MATERIALS

INDUSTRY NEWS INTERNATIONAL DIARY

ULTRASONIC ATOMIZATION FOR UNIFORM DISPENSING AND COATING OF

Jan/Feb 2009

Nov/Dec 2008

TRANSFER PRINTING: AN EMERGING TECHNOLOGY FOR MASSIVELY PARALLEL ASSEMBLY OF MICRODEVICES

Bjorn Dahle Interview Inside NEW PRODUCTS INDUSTRY NEWS INTERNATIONAL DIARY

NANOPARTICLES SOLAR: IT’S ABOUT TIME

issue_2.1.indd 1

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News for the Solar Manufacturing Industry

Volume 2 Number 3 May/June 2009

Volume 2 Number 4 July/August 2009

Steamer vS. torch in Pv manufacturing—a coSt of ownerShiP comPariSon

comBing in the energY

Dr. Madhusudan V. Atre Interview Inside NEW PRODUCTS INDUSTRY NEWS INTERNATIONAL DIARY

The imporTance of cpk Debugging anD verifying microinverTers for phoTovolTaic insTallaTions lasers, for more efficienT solar cells

News for Solar Manufacturing Industry

Volume 2 Number 2 March/April 2009

SOLAR INTEGRATION TAKES A PAGE FROM THE SEMI WAFER CSP PLAYBOOK

NEW PRODUCTS

LASER SCRIBING TOOLS EDGE IN FRONT

INDUSTRY NEWS INTERNATIONAL DIARY

March/April 2009

PerSPectiveS on SemiconDuctor ecoSYStem—the SoLar route

Global Solar Technology Volume 2 Number 2

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News for the Solar Manufacturing Industry

CONFORMAL COATING IMPROVES THE RELIABILITY AND LIFE OF SOLAR INVERTERS

Rajinder Kumar Interview Inside NEW PRODUCTS INDUSTRY NEWS INTERNATIONAL DIARY


Industry News news Industry

Industry news New photovoltaic industry association to form A new professional association serving engineers and management in the photovoltaic cell and module manufacturing industries has been proposed. A formation meeting will be held on June 10, 2010 from 5:30-7 p.m. at Flextronics Corporation in Milpitas, CA. Matthew Holzmann, president of Christopher Associates Inc., said, “The photovoltaic industry is moving fast. We are all pushing hard. There are few professional resources out there for the engineering and manufacturing community on an individual basis. We have tradeshows and some standards work being done, but engineering education, technology benchmarking and other professional issues and opportunities must be addressed as well. Hopefully we can begin a dialog to meet this need.” In order to facilitate the discussion, Flextronics Corporation has offered to host a formational meeting for such an organization. The meeting is open to all, and will be held at: Flextronics Corporation Building #1 Milpitas Conference Room 637 Gibraltar Court Milpitas, CA 95035 Contact: Dennis Willie For more information or to RSVP, please e-mail matt.holzmann@christopherweb.com. Axion Power awarded government grant to develop solar power storage system Axion Power International, Inc., the developer of advanced lead-carbon PbC® batteries, today announced that it has been awarded a state grant to develop a renewable solar energy storage system based on its proprietary PbC™ PowerCube battery technology. The $300,000 grant from the Solar Energy Program of the state’s Commonwealth Financing Authority will be used to demonstrate the advanced energy storage technology of PbC batteries within a “Smart Grid” system where power is generated from renewable energy sources such as the sun or wind, stored during slower, overnight periods and then delivered to the grid during times of peak demand. The Axion

4 – Global Solar Technology – May 2010

Applied Materials expands in Taiwan.

PbC batteries will be coupled with a UPS power conditioner provided by Eaton Corporation, and a solar panel-to-electric conversion system, as well as an electric vehicle charging station, provided by Envision Solar. The Axion grant was the only storage project approved as part of the state’s Solar Energy Program. The other 12 approved projects were for solar generating systems. www.axionpower.com Eyelit’s integrated manufacturing execution (MES) software selected by Deutsche Solar AG Eyelit Inc. announced that Deutsche Solar AG, the wafer-manufacturing subsidiary of SolarWorld AG, has selected Eyelit’s MES Software Suite to support PV wafer production ramp in its new 500 MW facility in Freiberg, Germany. Eyelit and its partner SYSTEMA GmbH were selected to provide a scalable solution for the management of factory assets and production, along with material traceability and visibility from raw silicon through wafer processing, including ingot and brick production areas. Deutsche Solar will utilize SYSTEMA’s expertise for factory automation, direct tool connectivity, and local support in Germany. www.eyelit.com

Applied Materials expands display, solar equipment manufacturing capability in Taiwan Applied Materials, Inc., opened its newly expanded Tainan Manufacturing Center in Tainan, Taiwan. The nearly 15,000 square meter facility will enhance Applied’s capability to serve its FPD and thin film solar PV customers in Asia while capitalizing on Taiwan’s excellent location, strong talent pool and supply chain efficiencies. The Tainan Manufacturing Center employs approximately 150 people and is expected to build and ship about 100 new PECVD and PVD systems this year, a 400% increase in shipments from last year. www.amat.com KYOCERA to manufacture solar modules in the U.S. Kyocera Solar, Inc., announced plans to begin manufacturing solar modules in San Diego, Calif., to serve the U.S. market’s growing demand for clean energy. The U.S. module manufacturing will support a new milestone for Kyocera’s solar energy business—global production capacity targeting 1,000 megawatts of solar cells per year (equal to one “gigawatt” per year) by March 2013. The new solar module manufacturing will begin in San Diego at Kyocera’s Balboa Avenue facility during

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Industry News

the first half of 2010, with an initial production target of 30 megawatts per year. www.kyocerasolar.com Scheuten Solar extends state-ofthe-art production line Scheuten Solar expanded its production line in Gelsenkirchen, Germany, with 60 MW, doubling its total production volume in 2010, compared to 2009. Scheuten added a multi-level laminator and newest generation stringers to its fully automated production line. The company also implemented an integrated quality control system that guarantees consistent high quality. With the extended production line, Scheuten makes sure it will have a total production capacity of approximately 200 MW by the second half of 2010. www.scheutensolar.com Alcoa and National Renewable Energy Lab testing new innovative concentrating solar power system Alcoa is jointly testing an advanced solar technology with the U.S. Department of Energy’s National Renewable Energy Lab (NREL), with the goal of making concentrating solar power (CSP) technology competitive in the United States by lowering its cost to generate energy. NREL and Alcoa recently installed a new Alcoa-designed Concentrating Solar Power parabolic trough at NREL’s test facility in Golden, Colo., USA. The series of tests will measure the 20-foot by 46-foot collector’s efficiency to generate energy and evaluate its structural performance. This round of validation at NREL follows

successful tests at Alcoa Technical Center outside of Pittsburgh, Pa., USA. www. alcoa.com NREL and 3M sign agreement on renewable energy research The U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) announced a series of Cooperative Research and Development Agreements (CRADAs) with 3M. The agreements between NREL and 3M establish joint investigations in three key areas of innovation: thin-film photovoltaics, concentrating solar power and biofuels. The CRADAs range from jointly identifying and developing critical aspects of renewable energy technology to accelerated testing of 3M designs and scaling-up successful prototype technologies for commercial production. The agreements last for at least one year. www.nrel.gov, www.3m.com The NPD Group acquires solar energy market research firm Solarbuzz The NPD Group has acquired Solarbuzz LLC, an international solar energy market research and consulting company. Solarbuzz will operate in conjunction with The NPD Group’s DisplaySearch, the worldwide leader in flat panel display and electronics market research and consulting. The acquisition extends The NPD Group’s global market and supply chain research expertise into the burgeoning solar energy sector. Solarbuzz will keep its brand name, and the Solarbuzz team will report to Tim Bush, general manager of The NPD

Alcoa and NREL test new CSP system.

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Group’s analyst-based services. www.solarbuzz.com, www.npd.com Magnolia Solar gets NYSERDA Program Award Magnolia Solar Corporation’s wholly owned subsidiary received a $1 million award from the New York State Energy Research and Development Authority (NYSERDA) to develop advanced thin-film solar cells in partnership with the College of Nanoscale Science and Engineering (CNSE) of the University at Albany. Magnolia Solar has the technology to capture a broader spectrum of the sun’s energy and to reduce energy losses due to reflection. This technology uses nontoxic materials on low-cost substrates to produce high-efficiency, low-cost solar cells. Magnolia Solar will work in close collaboration with faculty and scientists from CNSE’s Energy and Environmental Technology Applications Center (E2TAC) at CNSE’s Albany NanoTech Complex to demonstrate its technologies in nanostructure-based thin film solar cells. The program, which is designed to improve energy efficiency while reducing production costs, is also being supported by Professor Fred Schubert at RPI. www.MagnoliaSolar.com Imec and partners start work on EU project PRIMA Imec announces that it has started work, together with its project partners, on PRIMA, a project under the EU’s 7th framework program for ICT (FP7). The project’s goal is to improve the efficiency and cost of solar cells though the use of metallic nanostructures. Next to imec, the project coordinator, the partners involved in PRIMA are Imperial College (London, UK), Chalmers University of Technology (Sweden), Photovoltech (Belgium), Quantasol (UK) and Australian National University (Australia). The aim of the FP7 project PRIMA is twofold. First, the project wants to gain insight into the physical mechanisms of metallic nanostructures, and in how they can improve the light absorption of the solar cell’s material. Second, the project’s partners want to study how these structures can best be integrated into the production of solar cells. For this, they will test a number of structures, benchmarking them against state-of-the-art solar cells. The performance and applicability of these cells will then be assessed by solar cell companies that are participating in the project. www.imec.be

Global Solar Technology – May 2010 – 5


A practical guide for improving crystalline solar cell efficiencies through firing process optimization

A practical guide for improving crystalline solar cell efficiencies through firing process optimization Bjorn Dahle, KIC, San Diego, California, USA

The crystalline solar cell manufacturing industry has long acknowledged that when solar wafers are processed with an optimal thermal profile, the solar cell efficiency increases. Studies from Heraeus and KIC have quantified that such process optimization may lead to significant increases in cell efficiencies up to several tenths of percentage points. (Refer to the end of the article for a link to a Heraeus and KIC study.) Because the solar cells are priced as a function of their efficiencies, the thermal process optimization potentially represents a significantly profitable endeavor. The difficulty, however, is twofold: 1. to obtain accurate and repeatable profile readings, and 2. to identify the correct furnace recipe to achieve an optimum thermal profile. This document focuses on optimizing the thermal process to help silicon solar cell manufacturers improve cell efficiencies while maintaining or improving productivity. The examples used come from the metallization process; however, the principles presented also are applicable for other thermal processes.

6 – Global Solar Technology – May 2010

Thermal process development As opposed to more mature industries such as semiconductor and electronics assembly, the solar industry currently does not have a clear understanding of the ideal wafer profile or process window for each unique application (wafer, silver paste, furnace and other variables). There may be numerous wafer properties and variables in the processes upstream from the metallization furnace that affect the ideal wafer profile. Therefore, each manufacturer must perform a design of experiment (DOE) to identify the best wafer profile or range of profiles (process window). Such a DOE typically involves changing the wafer profile while the cell efficiency, fill factor and other quality measurements are measured. The profile is changed numerous times (on identical wafers that have been processed up to the firing furnace) in a “trial and error” approach until the responsible engineer is satisfied with the cell efficiency. The wafer profile itself is a result of the furnace settings and how the thermodynamic properties of the furnace heat and cool the wafer. A modern metallization

(firing) furnace can be set up using tens of millions of alternative recipes (combination of zone temperatures and conveyor speed), making the DOE both difficult and time consuming. Even worse, when changing one profile parameter, e.g. the peak temperature, all the other parameters such as time above 500˚C, time above 600˚C, ramp rate, etc. also change. As a result, it becomes difficult to determine what caused the improvement in the cell efficiency. Finally, the traditional methods to record the wafer profile suffer from inaccurate and non-repeatable measurements. This problem is caused by the method used to attach the thermocouples (TC) to the wafer. It is not uncommon to get a 50˚C difference in peak temperature readings from one profile to the next when taken only minutes later. Clearly, a new TC attach method is required before any purposeful DOE can take place. Trial and error experimentation for improved wafer profiles The following steps are recommended to explore new and improved wafer profiles

  Figure 1. Initial furnace setup and associated profile and cell efficiency.

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A practical guide for improving crystalline solar cell efficiencies through firing process optimization

that result in higher cell efficiencies: 1. Initial furnace setup and associated wafer profile The starting point for the DOE is whatever furnace set points (recipe) are currently being used. Alternatively, the responsible engineer may use his knowledge and experience to select the initial setup. One option for factories with multiple production lines is to use the profile in the furnace that yields the highest cell efficiency. When selecting a particular combination of conveyor speed and zone temperatures, the furnace recipe will yield a specific wafer profile and associated cell efficiency as depicted in Figure 1. 2. Second furnace recipe To experiment with new and improved profiles, the responsible engineer may use his or her knowledge and information about wafer and silver paste properties, etc. to change the profile in certain directions. (The profile data and cell efficiency numbers in this article are only established to illustrate the process optimization method. The actual numbers vary with each application. The temperatures used in these examples are higher than what the industry has been used to seeing. This is a result of the more accurate readings experienced with the use of modern flattened TC bead thermocouples that record data much closer to the actual wafer temperatures). In this example of a multi crystal wafer let us change the peak temperature in increments of 10˚C. We need to find the furnace recipe that increases the peak wafer temperature from the current 830˚C to 840˚C as seen in Figure 2. The engineer will set up the furnace to the newly chosen recipe, wait for the furnace to stabilize at the new temperature(s), run one or more wafers through the furnace, and measure their average cell efficiency.

  Figure 2. New furnace recipe and associated wafer profile and cell efficiency.

the best. The problem with this experiment is that although we focused on changing the peak temperature, all the other dimensions of the profile likely changed as well. Figure 5 shows how time above 500˚C and 600˚C kept changing. At this point, we do not know whether the peak temperature or time above 500˚C or 600˚C contributed to the changes in cell efficiency.

Select furnace recipes that only change the peak profile while keeping everything else constant What is needed is the capability to only change one variable at the time. Modern process optimization software enables the user to lock in all but one parameter at a time. The engineer needs to ask the software to identify the recipes that change the peak temperature in 10˚C increments

  Figure 3. Third recipe resulting in a profile yielding higher efficiency again.

3. Third furnace recipe The cell efficiency increased when running the furnace at recipe 2, so let us change the recipe again to achieve a peak temperature of 850˚C (Figure 4). 4. Fourth furnace recipe The cell efficiency improved (Figure 3) so let us increase the peak temperature yet again, this time to 860˚C. 5. Fifth furnace recipe The efficiency dropped (Figure 4). It is tempting to conclude that the previous profile with a peak temperature of 850˚C is

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  Figure 4. New recipe resulting in a profile yielding lower cell efficiency.

Global Solar Technology – May 2010 – 7


A practical guide for improving crystalline solar cell efficiencies through firing process optimization

while keeping time above 500˚C and time above 600˚C the same as depicted in Figure 6. The process optimization software essentially evaluates all of the millions of alternative furnace recipes, and it predicts the resulting wafer profile

for each. It then selects the furnace recipe that produces the requested profile. The Spectrum will provide its recommendations within seconds of completing the profile run. The cell efficiency changes are now a

direct result of the peak temperature only. Once the highest efficiency has been found based on the peak temperature, (recipe 6 in Figure 6), this dimension can be locked while changing one of the other profile parameters. This continues until the highest cell efficiency has been found.

  Figure 5. DOE where multiple profile variables changed simultaneously.

  Figure 6. New recipes increase the peak temperature on the wafer in 10˚C increments while keeping the other profile dimensions stable.

 

8 – Global Solar Technology – May 2010

Transferring the process from the pilot line to the production lines The simple but efficient process improvement guideline above will yield results quickly. Most companies will perform such work in the laboratory furnace or pilot line furnace. The next challenge is to transfer the optimum process (or profile) to the production lines (Figure 7). Because the production line furnaces are different than the furnace where the process was developed, the process transfer may be difficult. Even if the production line furnaces are of the same make and model, they will have different thermodynamic properties due to wear and tear, aging heating lamps, preventive maintenance changes, and more.

Process transfer from the Pilot furnace to the production furnaces The solution is to enter the optimal profile into the SunKIC profiler, run a profile, and to ask the Spectrum software to identify which setup will yield the requested profile for each production furnace (Figures 8 and 9). Each production furnace will have different settings, but they all will produce the same wafer profile. The Spectrum software makes the process transfer extremely quick even when the furnaces are all different. The final aspect of setting up and running a solar cell firing process in the “sweet spot” of the cell efficiency is to periodically adjust the furnaces in a similar fashion to the above when the process starts drifting. The thermodynamic properties of the furnaces will change over time due to aging lamps, preventive maintenance and more. Due to the strong financial benefits of consistently producing solar cells with high efficiency, the furnaces should to be adjusted when the measured cell efficiency drops. The good news here is that automatic process optimization software will identify the correct furnace settings within seconds of running a profile, hence minimizing production downtime. Conclusion Fine tuning the firing furnace to achieve a more optimal wafer profile leads to

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A practical guide for improving crystalline solar cell efficiencies through firing process optimization

higher cell efficiencies and, hence, higher profitability. This article demonstrates easy steps to achieve this even when the ideal profile or process window is unknown. Due to the dynamic nature of the thermal process that will drift throughout the day, week and month, it is important that the furnaces are adjusted when the profile changes. This can be achieved quickly with little or no effect on production downtime. Heraeus-KIC study on increased cell efficiency as a result of profile optimization: http://globalsolartechnology.com/index. php?option=com_content&task=view&id=40 38&Itemid=5

  Figure 8. Transfer the optimized process to the first production line.

Figure 9. Transfer the optimized process to all the production lines.

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Bjorn Dahle, KIC, may be contacted at 16120 Bernardo Center Dr., San Diego, CA 92127; 858-673-6050; E-mail:bdahle@kicmail. com; Web site: www.kicthermal.com.

 

Global Solar Technology – May 2010 – 9


Smart packages for CPV cell devices

Smart packages for CPV cell devices Andy Longford, consultant, and Domenic Federici, Interplex Engineered Products

Without doubt, the future of renewable energy systems that utilise concentrator photovoltaic (CPV) principles depend absolutely upon the capability to build cost effective CPV cell modules. The system energy cost is continually being driven down, and new CPV systems have to be ahead of the game both in terms of providing efficient light to energy conversion and low “dollar per watt” electricity generation. The big advantage for CPV modules is that they use relatively small, photosensing diode devices. These are virtually the opposite of light emitting diodes (LED) and can, with some smart design, be developed to utilise much of the manufacturing technologies that have recently mushroomed for the fast growing LED industry. The small compound semiconductor solar cells can be manufactured by using optoelectronic semiconductor assembly techniques (wire bonding, dicing, pick and place, etc.) for cost effective assembly and encapsulation. In particular, CPV does mirror the latest HB LED technologies which use semiconductor assembly processes with new technology developments to achieve low cost, high volume production.

Development of concentrator PV Optical diodes convert light and energy in two basic formats. As light emitters, they output light when energised, or as photosensors they emit an electric current when exposed to photons of light. Much work has been done in recent years, and continues on, to utilise new technologies for making photodiode devices more efficient. LEDs in particular are today a very high profile industry as the efficiencies improve and the usage of LEDs for lighting has created a very high demand for high brightness devices. Conversely, the solar power industry is seeing the uptake of photosensing devices to convert the energy of sunlight into electricity. With the use of lenses, as we all know, sunlight can be focussed to a very small point of high intensity light. This intense, concentrated light can be converted by high efficiency photodiodes into significant amounts of energy. In 2003, a European Funded, Framework 6 project entitled “FULLSPECTRUM” (see www.fullspectrum-eu.org) set out to develop this light concentrator technology (Figure 1). The overall goal of the project was the better exploitation of the solar spectrum in the photovoltaic (PV) conversion of the solar energy. The conventional, single semiconductor, solar cells only convert the

photons of energy close to the semiconductor bandgap effectively. Photons with less energy are not absorbed and their energy is totally wasted whilst photons with too high energy only use a fraction of it. This project looked at the use of compound semiconductor materials, the “III-V” multijunction (MJ) cells, along with manufacturing technologies for novel concepts including assembling. The results did lead to a major development programme to industrialise the concepts and produce high performance CPV modules. The United States National Renewable Energy Laboratory (NREL) continues to be the arbiter for the development of efficient PV cell devices utilising MJ devices and regularly publish data covering the developments of high efficiency cells. NREL are working with a number of R&D projects in concentrating solar power, focussing on parabolic trough solar technology and advanced concentrating solar power technologies to support the U.S. Department of Energy in its concentrating solar power deployment efforts. These CPV systems use lenses or mirrors to concentrate sunlight onto high-efficiency solar cells. Although typically more expensive than conventional cells used for flat-plate (typically Silicon) photovoltaic systems, these solar cells utilise the light

  Figure 1. The photovoltaic concentrator developed by the ‘Fullspectrum’ project.

10 – Global Solar Technology – May 2010

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Smart packages for CPV cell devices

concentration to decrease the required cell area while also increasing the cell efficiency. NREL state that CPV technology offers the following advantages: • Potential for solar cell efficiencies greater than 40% • No moving parts • No intervening heat transfer surface • Near-ambient temperature operation • No thermal mass; fast response • Reduction in costs of cells relative to optics • Scalable to a range of sizes. However the high cost of advanced, high-efficiency solar cells must utilise cost-effective concentrator optics and cell assemblies to enable concentrated sunlight systems to achieve a comparison with other solar power options. CPV cells Solar cell size is a key aspect in concentration applications. The optimum size for a GaAs solar cell operating at 1000 suns is about 1 mm2. (Operation at 1000 suns means a light power density of 1 MW/m2.) A small size cell maximises the efficiency and if a 1 mm x 1 mm size is chosen, this is very close to that of a LED device (Figure 2). Yet because III-V multijunction solar cells operate at lower photocurrent than single junction, a triple junction (3J) with a size of 1 mm2 requires a high light intensity in order to provide a good conversion. However, operating at 1000 suns means that the light power received by the solar cell is 1watt. Assuming an efficiency of 35%, then 350 mW of this energy is converted into electricity, while 650 mW is transformed into heat. Although a heat intensity of 650 mW/mm2 does not require active cooling, and heat extraction of several hundred of mW is well developed for high power LEDs, the CPV devices do need good thermal management built into the system to ensure long term reliability. The MJ CPV cell device is a semiconductor device that needs to be interfaced and mounted onto a base that can provide an electrical interconnection as well as some form of thermal dissipation. In semiconductor terms, the cell devices are quite large as typically the industry is moving towards the 5 mm x 5 mm size rather than the smaller 1 mm x 1 mm. Some applications are using even larger 10 mm x 10 mm devices. Even so, all semiconductor devices need to be protected from damage caused by handling, mounting into systems, ambient conditions and moisture. Hence, these devices need some form of circuit board,

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Figure 2. A typical GaAs 1 mm x1 mm CPV cell units. (Courtesy of Isofoton)

substrate or package to allow the connections between one another and the outside world. This is course similar to the needs of the LED devices. LEDs and high brightness (HB)LEDS in particular, are mounted in small surface mount housings (packages) that have integral heatsinks and are sealed with a silicone optical gel (Figure 3). In the CPV world, most cell modules also incorporate bypass diodes as protection from “dark current.” This is a potential problem when one of the cells in the system is damaged, weak or (most likely) in shade. Then there is the risk that full current from the rest of the cells could pass through the shaded device and cause overcurrent damage. Essentially, concentrator cells must therefore comprise a small, high efficient, multijunction cell, together with a bypass diode, suitably housed in a robust package that will provide thermal management, protection of the device from ambient dust, dirt and moisture, and an optical interface (support and alignment) with the light gathering structures (lenses). This package must also ensure long term reliability and be low cost...definitely a “smart package.” Comparison to HB-LED technology Typically there are 4 main parts required for a HB LED or a CPV cell package, as shown in Figure 3. • A housing (package body) • Interconnection terminals (leads) • Thermal management (heatsink) • Optics support.

These elements do not necessarily have to be individual items and for cost advantages. Lhe LED industry has developed a number of packages that combine most of these elements together. In terms of the manufacturing processes, LED fabrication yields of 95-98% are standard while silicon PV is in a lower range of 90-95%. If the HB-LED is considered, the

 

  Figure 3. Structure of a high-brightness LED. (Source: Lumileds™)

packages are also developed to be suitable for assembly on high throughput assembly equipment as used by semiconductor chip assembly companies. The package is typically on a carrier, or lead frame, that can work with automated pick and place ‘die attach,’ wirebond, sealing and testing machinery. The assembly equipment ensures that the chips are accurately located (within microns) to provide exact optical alignment with the seal or lens focal planes. Devices are then singulated and packed into tubes or carrier tapes to enable handling, storage and ease of use for insertion and assembly into the application requiring the LED. The application subsystem will also provide additional thermal management (heat sinking), electrical connections and probably additional optical alignment. A CPV solar application has identical assembly requirements and the use of prepackaged cell units is now becoming the optimum solution to ensure high quality and long term reliability of CPV modules. CPV cell packages Thermoplastic injection molding technologies used to provide cavity chip package solutions is one the key emerging technologies for the electronics industry. A chip package is just a box with connectors, and plastic molded connectors are in themselves part of a fast moving industry high technology, high volume industry. Molding high performance engineering plastics, such as liquid crystal polymers (LCP), to pre-formed copper leadframes, is the choice for packages for sensors, MEMs, LEDs and other electronic devices. This technology is now the cost effective choice for “smart” CPV packages. As discussed, there are a number of crucial factors that must be combined into the design of a CPV cell package. As volumes develop, it would seem prudent to ensure that such devices incorporate the use of low cost Assembly capabilities and adoption of “standard” semiconductor ‘back-end’ assembly processes is the only

Global Solar Technology – May 2010 – 11


Smart packages for CPV cell devices

  Figure 4. A CPV package unit on leadframe carrier.

 

  Figure 5. The assembly of a basic CPV package unit.

way to go for this. The package must therefore take into account the requirements of the manufacturing systems: small sizes, carrier frames, die attach, wirebond, pick and place, etc. Optical alignment is also a crucial part of the solar cell unit. Chip packaging is, in general, a proven technology for ensuring alignment of devices in the ‘X’ and ‘Y’ planes but a CPV cell is actually a “3D” device. There has to be a focus of light onto the chip, and therefore, depending upon optics, the package has to be aligned to the “Z” plane to ensure optical conversion efficiency. It is feasible, as with LED packages to build some form of X, Y and Z alignment into the packages and this is easily done utilising plastic injection mold capabilities. However, as there is no “standard” optical design, the package design is then really a match for the “unique” optics that may be used. It may be more effective to use an available “standard” low cost package, always a smart choice, and utilise a separate “lens holder” to customise the system. Power dissipation needs are foremost, to ensure efficiency and reliability of the cell. Utilising a leadframe technology as opposed to a ceramic or organic substrate allows for a substantial metal mass to be utilised as a die pad. This pad also acts as a heat-sink and enables much simpler thermal management within applications. Interplex Engineered Products have developed a number of unique injection molding systems that allow two separate leadframe formats to be molded together at the same time, and by incorporating this technology into the designs, they have produced a package technology that allows the interconnection leadframe to be electrically isolated from the die pad/heatsink frame. Using frame technologies, rather than “drop in” metal slugs is a much lower cost process and is much more applicable to high volume applications. The design of a simple looking chip housing, the molded plastic part, is really the ‘smart’ part of the package. It provides protection for the metalwork, insulation

12 – Global Solar Technology – May 2010

Figure 6. Cross section of a basic CPV package unit.

for the system components, a methodology for optical alignment and connection apertures for electrical interconnection to the rest of the system. SMART packages The package design in Figure 4 incorporates the Interplex unique, patented, dual lead-frame design, integrating a thick copper base die pad as a heatsink, with a standard lead-frame structure in a high temperature LCP thermoplastic enclosure. This ensures excellent heat transfer from cell to heat sink via the copper lead-frame ensuring increased cell efficiency. The design of the package molding allows for flexible secondary optics mounting, suiting the varied and different module designs that CPV system manufacturers are now considering. It is also designed to have inexpensive interconnect spade terminals for low cost integration of cell systems enabling a lower total cost of assembled receiver due to simplified assembly operations. These packages offer significant advantages compared to the alternative methods of component assembly utilizing metallised circuit boards such as ceramic substrates or mounted onto direct bond copper (DBC) or insulated metal substrates (IMS). Thermal management is built in, secondary optics are easily mounted, and isolation between cell and system housing can be achieved very simply with a variety of materials. Furthermore, a packaged cell device allows easier and safer handling, quicker assembly and test of the system as well as simpler repair and replacement, making the designs more future proof as better ‘III-V’ cell designs and efficiencies are developed. This design of package will also easily lend itself to customisation or scaling to suit different size cell devices and different interconnection needs. Examples of such designs are shown in Figure 5 and 6. One is for surface mount and the other is designed for interconnection wires (cables) to be soldered to the packages.

Conclusion Interplex have taken the lead in developing a range of ‘smart’ package options for the developing CPV solar energy market. They have developed a range of package designs offering a user friendly solution for the component user as well as the device supplier (Figure 7). To ensure that cost effective devices will become available they have produced a package that enables the CPV technology industry to adopt manufacturing skills already developed for the Semiconductor, particularly the LED, industry. The “standard” semiconductor assembly processes offer proven technology, with efficiency and automation to meet low cost assembly needs of the CPV industry. The designs to match these processes utilise readily available low cost materials, to provide a package solution that is the ideal option for both sample testing and production applications. These “smart package” developments now offer the manufacturers and users of photosensing power LED and CPV devices a robust, thermally enhanced housing coupled with simple interface connectivity.

Figure 7. A CPV cell fully assembled. (Courtesy of Spire)

Andy Longford is a technical support consultant and Domenic Federici is the business development director for Interplex Engineered Products (IEP), 231 Ferris Avenue,East Providence , RI 02916 USA. Tel:(401) 434 6543. www.interplex.com/iep IEP is a turnkey, vertically integrated world-class supplier of application specific thermoplastic Electronic Packages and a division of Interplex Industries Inc.

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Achieving thermal uniformity in photovoltaic applications

Achieving thermal uniformity in photovoltaic applications Jake Lindley, Watlow

This article will explore some of the more common issues in thermal system design that can lead to poor thermal uniformity. It will also provide some methods and guidelines for the design of thermal system in order to avoid common pitfalls.

Keywords: Thermal System Design, Edge Effects, Thermal Leaks, Thermal Uniformity

As photovoltaic cell manufacturing methods continue to evolve, achieving thermal uniformity across a target (typically consisting of silicon wafers, large float glass plates or a metallic web) persists as a common theme in the application of process heat. Excessive variation in temperature can lead to a myriad of problems including warped or broken substrates, inconsistent layer thickness during deposition, poor penetration during diffusion or incomplete chemical reactions. All of these issues can lead to increased takt times, lower yields and increased cost per module. Not accounting for edge effects Typical photovoltaic substrate heating systems often utilize large radiant or conductive heater panels to impart energy on a target. Intuition may lead one to the conclusion that a uniform power density on the heating system will result in a uniform temperature distribution on the substrate be it continuous (metallic or polymer web) or discrete (silicon wafer or glass plate). In fact, due to heat losses at

the edges, the resulting temperature profile would be highest in the center and would decrease with proximity to the edge (Figure 1a). These “edge effects” would be most severe at the corners of discrete targets. To create a uniform temperature on the substrate, the heater should be designed to prevent or offset heat loss at the edges. A variety of techniques can be used independently or in combination for greatest effect. One way is to increase the size of the heat source with respect to the target thus allowing for some edge margin (Figure 1b). The necessary size of this margin is directly dependent on the thermal uniformity desired by the manufacturer. Alternatively a “picture frame” approach (Figure 1c) to power distribution may also be employed to offset the edge losses. This power distribution can be produced by creating two discrete zones of control or by changing the power distribution of the heater element itself. A third method of dealing with this phenomenon is the use of insulation or heat shields at appropriate locations around the source to minimize edges losses (Figure 1d).

Figure 1a. (left) Uniform heat source. 1b. (second from left) Uniform heat source utilizing edge margins. 1c. (right) Zoned heat source utilizing edge margins. 1d. (far right) Zoned heat source utilizing edge margins and reflector shields.

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Global Solar Technology – May 2010 – 13


Achieving thermal uniformity in photovoltaic applications

Not accounting for additional thermal “leaks” The effect of ancillary mechanical structure is often overlooked when designing a thermal system. This mechanical structure typically includes mounting or holding features for the heat source, target, sensing devices and power leads as well as chamber walls, doors, lift pins, ports, etc. (Figure 2a). Thermal leakage can be minimized by utilizing the smallest geometries as mechanically possible to support both the heat source and the target (Figure 2b). Further reduction in thermal leakage can be achieved by increasing the path length between hot and cold design features or by utilizing thermal breaks (lengths of nonthermally conductive materials) within the leak path (Figure 2c). Not accounting for the introduction and removal of the target (intermittent movement of target substrate) Introduction of relatively cold targets to a pre-heated source is a potential for non-uniformity, which increases with the direction and speed of the target. Ideally a target would be introduced to a planar source in a direction perpendicular to the emitting plane of the heat source. In many processing scenarios this is impractical. Often targets move parallel to the emitting plane of the heat source, which requires the source to target temperature delta and speed of introduction to be closely managed to minimize non-uniformity. If uniformity is also required throughout the entire thickness of the substrate, (typically required when the heat source is opposite the side being processed) an appropriate soak or dwell time must also be considered to allow heat transfer through the substrate. This is especially true in nonmetallic substrates with relatively low thermal conductivities. The use of pre-heat chambers or inclusion of a heat source on both faces of the target substrate where possible can minimize dwell times. Improper orientation of heat source (continuously moving target substrate) In the case of continuously moving substrates, the orientation of the heat source is critical to avoid “thermal striping” of the moving substrate (Figure 3a). In applications utilizing exposed element, tubular, cable or cartridge style heating elements uniformity can be enhanced by orienting the long axis of the heating element perpendicular to the movement of material (Figure 3b). It is also common

14 – Global Solar Technology – May 2010

Figure 2a. (left) Standard mechanical supports. 2b. (middle) Thinner mechanical supports. 2c. (right) Long path mechanical supports with thermal break.

to embed the heating elements in a conductive metallic plate. Aluminum is preferred due to its favorable thermal conductivity; however, stainless steel and other alloys may be used in higher temperature applications. The metallic plate serves as a heat spreader that when properly designed can provide a thermally optimized source. Orientation in relation to the moving substrate becomes less important when employing this technique. It is important however to address edge effects using the techniques discussed above.

Not accounting for gas flows within a chamber A final factor that must be considered during any thermal system design are gas flows. The majority of photovoltaic cell processing occurs in an evacuated chamber. Many involve gas flows into and out of the process chambers. Examples include load locks where the chamber cycles between vacuum and atmosphere or deposition processes where various gases are pumped into an evacuated chamber. In these scenarios, a clear understanding of gas flow is necessary. Obviously an effort should be made to make gas flow into the chamber as homogeneous as possible

Figure 3a. (top) Heat source parallel to direction of travel. 3b. (bottom) Heat source perpendicular to direction travel.

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Achieving thermal uniformity in photovoltaic applications

through the use of diffuser plates or other mechanisms. This is especially important if the gas impinges directly onto the target. To the extent possible the relative temperature difference between the gas flowing into the chamber and the target should be minimized. If these simplistic approaches do not provide a satisfactory level of performance, more detailed study must be given to the gas flows within the chamber and their effect on the target and source. Once this is understood, a custom zoned heating element can be designed to minimize effects of the gas. Conclusion As discussed above the solution to many of the most challenging thermal uniformity problems often lies in the ability to properly size and orient the heat source with respect to the target. Further

improvements can be achieved by dividing the heat source into multiple zones. These zones can be independently controlled for maximum tuning of the heat source or can be created using a “fixed” wattage distribution approach if heat losses during the process are consistent. Ideally a heat source would be designed to incorporate as many independently controlled zones as possible such that the system could be tuned to an exact thermal profile. However this is not always practical as each control loop adds additional cost to the overall system. Typically some combination of “fixed” wattage distribution and independently controlled zones are incorporated into a system to optimize the trade-off between performance and cost. There are a number of heating technologies commonly employed in the processing of

photovoltaic cells. Each technology has its own unique set of attributes to offer the industry. Utilizing these basic rules along with the appropriate heating, sensing and controlling technology should help improve the thermal uniformity of your system. This will lead to better process control, reduced takt time and increased yields, all of which serve to reduce the cost of photovoltaic cell processing. Processes that require a level of thermal uniformity beyond these basic guidelines could benefit from the expertise of companies that specialize in the development of thermal systems. Jake Lindley is a senior engineer at Watlow where he specializes in the design of complete thermal systems including heaters, sensors and controls.

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systems for several applications. Tonsan’s dispensing systems provide significantly reduced materials costs, less waste, more efficient application, and reduced maintenance and cleaning. For further information www.tonsan.com www.christopherweb.com

Global Solar Technology – May 2010 – 15


High-performance labels for the solar photovoltaic installation industry

High-performance labels for the solar photovoltaic installation industry Lauren M. Catalano, Tyco Electronics Corporation

Three label samples—one premium vinyl, one cast vinyl and one calendered vinyl—are performanced tested through exposure to UV light with water spray, salt spray, and thermal shock. This paper presents the findings.

Keywords: Labels, Marking, Installations, Performance Testing

Introduction Every day, solar photovoltaic installers struggle with correctly marking their installations in a way that is practical to implement and that meets the expectations of inspectors. Engraved plates and phenolic plaques are very durable, but require screws or rivets to affix them. The simplest solution to mark installations is to use adhesive labels, but standard labels often fade or peel away after being exposed to years of sunshine and weather. However, high-performance labels achieve the goal of correctly marking the installation while providing a longterm solution that easily adheres to the components of the system. The reasons why the labels are effective can be analyzed in the following steps: 1. The construction of the labels 2. The materials used 3. The test procedures to confirm performance Label construction Labels are primarily constructed of the following components (Figure 1): • A top coat (consists of ink, varnish and/or overlaminate) • The base film • The adhesive • The release liner

Figure 1. Construction of high-performance labels for solar applications.

Description of samples See Table 1. Label materials The lamination material is a clear film formulated with UV inhibitors intended to filter out the destructive rays of UV radiation. This lamination not only provides added protection against ink fade, but also provides protection against moisture and salt spray. The ink systems used on all labels under test are comprised of specially engineered pigments that have a relatively high resistance to prolonged UV exposure. The ink pigment used in the solar labels is also used in the automotive industry and has a long-standing history of outdoor exposure. Many of the colored inks being considered for solar labels are currently

Sample

Identification

Description

Test Substrate

1

SOL 1

Premium vinyl, special ink & laminate

Powder coated painted stainless steel

2

SOL 2

Cast vinyl, special ink & laminate

Textured powder coated painted aluminum

3

FLEX 2

Calendered vinyl, special ink & laminate

Textured powder coated painted aluminum

Table 1. Description of samples.

16 – Global Solar Technology – May 2010

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High-performance labels for the solar photovoltaic installation industry

Figure 2. Redness test results.

used in Department of Transportation applications. The base material used is a highperformance, 2 mil (0.002 in) vinyl film with a high tack permanent acrylic adhesive. The material is formulated with premium raw material and processed to produce a vinyl film that resists the rigors of outdoor elements. The base film has been proven successful when used in other outdoor applications in other industries. The permanent acrylic adhesive incorporated in the “SOL” material is appropriate for such outdoor applications as it has a proven track record of adhering to materials such as metal, glass and plastic substrates while exposed to extreme weather conditions. Test conditions including UV exposure, simulated rain, salt spray, thermal shock and fluid have revealed excellent resistance to fading, delamination, bubbling, cracking, hazing and chalking. The base material used in the “Flex” sample is a basic calendered white vinyl with a permanent acrylic adhesive. The plasticizers and pigments used in the formulation of this vinyl are very common. The permanent acrylic adhesive incorporated in the Flex material is a typical pressure sensitive adhesive with moderately aggressive adhesion properties. The release liner, although not a functional property of the label, is an important component in the label construction for its “lay flat” properties for sheet stock labels and for its non-blocking properties when in roll form. Performance testing The labels were tested in three ways: exposure to UV light with water spray, prohesion (salt spray) and thermal shock.

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Figure 3. Lightness test results.

UV Exposure: The test material, SOL 1, SOL 2 and Flex 2 were evaluated in accordance with ASTM D3424 Method 4. The test incorporated three main weathering forces: light, heat and moisture. The procedure was to expose the material to only 102 minutes of light at 63˚C Black Panel Temperature at 0.55 W/m² at 340 nm using Daylight Q filters, followed by 18 minutes of light and water spray—the intensity of the light comparable to the average summer sunlight irradiation in Florida. The temperature was kept fairly high and water was sprayed on the panels for 18 minutes out of every two hours. Testing was conducted over 5,000 hours to replicate the rough equivalent of 25 years of sunlight. Figures 2 and 3 show the results for redness and lightness of the UV testing. Explanation of color measurements: • Redness Factor: Measures the “redness” of the base color. The higher the number is, the redder the object. • Lightness Factor: Measures fade. The higher the number is, the more the fade has occurred. Salt Spray: The second test was for salt exposure or the prohesion cycle per ASTM G85 Annex 5. The test procedure included the cycling of: • 1 hour of salt fog at ambient conditions • 1 hour of drying at 35˚C • The fog was a fine mist of dilute salt solution with humidity close to saturation. The materials were subjected to 504 hours of continuous fogging and continuous drying. All samples passed this test.

Thermal Cycling: The third test was for thermal cycling, but it did not follow an ASTM test standard. During the four weeks of testing, the samples were cycled from -5˚C to 120˚C in 25 cycles with a 30 minute dwell time at each temperature causing expansion/ contraction stresses. A weekly observation for delamination, cracking and bubbling was conducted. All samples passed this test. Conclusion 1. The results from the UV exposure test for the SOL material revealed superior performance in terms of color fastness. The Flex 2 sample revealed significant chalking, causing the ink contrast to become significantly less legible. 2. Additional observations during the UV testing showed that the Flex 2 sample revealed obvious shrinkage and some bronzing. 3. The SOL samples did not reveal any sign of chalking, bubbling, shrinkage, cracking or delamination. 4. The SOL material has built in UV inhibitors and aggressive adhesive designed to resist the rigorous outdoor elements. The premium chemicals used as additives in the SOL vinyl have a stronger internal bond, thereby mitigating the chalking and shrinking effects exhibited by the other vinyl material. 5. The SOL samples passed the rigorous test that simulated approximately 25 years of UV exposure. This highperformance label, with UV-resistant ink and UV-resistant overlamination, will perform well when used to mark a solar photovoltaic system.

Global Solar Technology – May 2010 – 17


Anayst Title buzz

Analyst buzz Solar market to grow by 64% in 2010, prices dwindle due to competition Installations of photovoltaic (PV) solar systems will soar in 2010, but a steep dive in the prices of solar components means industry competition will intensify, according to iSuppli Corp. “Global installed watts for PV systems will grow by 64 percent in 2010, reaching (GW),” said Henning Wicht, senior director and principal analyst for photovoltaic systems at iSuppli Corp. “This will bring a return to the growth levels seen before the fall of 2008 as the worldwide recession recedes and as new geographies and segments of demand emerge.” Despite the projected return in demand for this year, the tremendous price erosion that occurred in 2009 continues to squeeze profits. On average, crystalline module prices last year fell by 37.8 percent, solar wafer prices plunged by 50 percent and polysilicon prices crashed by a gut wrenching 80 percent. This trend will continue in 2010, although at a slower rate. Crystalline module prices will drop by 20 percent, wafer prices will decline by 18.2 percent and polysilicon prices will fall by 56.3 percent. “The erosion in pricing is bound to change the face of the solar industry,” Wicht said. “The freefall of PV prices represents a permanent ratcheting down of price structures that will transform the industry into a more competitive marketplace.” Given the enormous downward shift in pricing, one major implication for the industry is that suppliers will need to continue accelerating cost reductions in

order to keep up with the price declines and to repair compressed profit margins. When the cost-down programs eventually catch up with the rate of price declines, an overall improvement in the profit picture can be expected, Wicht said. After suffering losses during much of 2009, PV profits will continue to improve in 2010, following a move into the positive during last year’s fourth quarter. iSuppli also is projecting that prices on average will pop back by more than 10 percent in the final quarter of 2010, despite declines for the entire year. The growth of PV installations in 2010 will be led by a newly energized German market, which recovered from sluggish performance in the first half of 2009 to achieve gradual growth in the second half—a trend expected to continue for the first six months of this year. The German market, however, could stall again by summertime, if the feed-in-tariff (FIT) designed to encourage the adoption of PV systems is trimmed by the Merkel government. The position in the overall PV

Worldwide solar photovoltaic market reaches record high of 6.43 GW in 2009 Worldwide solar photovoltaic (PV) installations reached a record high of 6.43 gigawatt (GW) in 2009—a 6% Y/Y growth, according to the latest Marketbuzz® 2010 Report from Solarbuzz®, an international solar energy market research and consult-

ing company, and a division of The NPD Group. In addition, the company reported that the PV industry generated $38 billion in global revenues in 2009, while successfully raising more than $13.5 billion in equity and debt, up 8% on the prior year. According to the company’s Marketbuzz 2010 Report, European countries accounted for 4.75 GW, or 74%

18 – Global Solar Technology – May 2010

market held by Germany—which accounted for 50 percent of total worldwide PV installations in 2009—is of such importance that the collective PV demand accruing from other countries will not be sufficient to compensate for a German FIT reduction of 15 percent if that were imposed in mid2010. Elsewhere, installations will continue to rise in both the established and the emerging regions, according to iSuppli. “Several new growth markets will come into play in 2010, the most significant of which are the United States, Italy and latecomer China,” Wicht said. “Together, these three markets will account for 50 percent of the growth projected to occur in 2010.” The PV space will also feature more players this year, led by South Korea’s Samsung and LG Electronics— already the world’s largest LCD panel makers and possessing vast experience at moving into new areas of operation—as well as Taiwan’s TSMC foundry and U.S. engineering giant Bechtel.

Source: iSuppli Corp

of world demand in 2009. The top three countries in Europe were Germany, Italy and Czech Republic, which collectively accounted for 4.07 GW. All three countries experienced soaring demand with Italy becoming the second largest market in the world. In contrast, Spanish demand in 2009 collapsed to just 4% of its prior year level. The third largest market in the world

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Analyst Buzz

was the US, which grew 36% to 485 MW. Following closely behind was a rejuvenated Japan, ranked fourth and growing 109% Y/Y. Worldwide solar cell production reached a consolidated figure of 9.34 GW in 2009, up from 6.85 GW a year earlier, with thin film production accounting for 18% of that total. China and Taiwan production continued to build share and now accounts for 49% of global cell production. Of total European demand, net cell imports accounted for 74% of the total.

The top seven polysilicon manufacturers had 114,500 tons per annum of capacity in 2009, up 92% Y/Y, while the top eight wafer manufacturers accounted for 32.9% of global wafer capacity in 2009. Solar cell production exceeding the market demand caused the weighted crystalline silicon module price average for 2009 to crash 38% from the prior year level. This reduction in crystalline silicon prices also had the effect of eroding their percentage premium to thin film factory gate pricing. Looking forward, the industry will return to high growth in 2010 and over the next five years. Even in the slowest growth scenario, the global market will be 2.5 times its current size by 2014. Using the fastest growth forecast, annual industry revenues would approach $100 billion by 2014. “Industry performance in 2009 was remarkable in that it managed to more than fully replace the 2.3 GW demand gap caused by the change in policy inSpain,” remarked Craig Stevens, president of Solarbuzz. “Looking forward, the industry will see a return to high growth, but in a low margin environment. Our analysis demonstrates that a wide range of start-up markets will help offset a slowdown in German demand in the second half of 2010.” After providing a comprehensive look

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back at 2009 industry results, the report devotes one-third of its content to the 2010-2014 forecast, including a thorough preview of market developments, policies, prices and production requirements that are essential to shape corporate strategies over this period. Solar PV systems market in Southeast Asia to reach US$ 255 million by 2016 Traditionally, in Southeast Asia, solar energy has been predominantly used for heating water and drying purposes and seldom for generating power. However, penetration of solar photovoltaic (PV) systems has been growing across the region over the last ten years, where it is used for electrifying rural and remote homes and villages. The solar PV systems market in Southeast Asia is at different stages of growth in different regions, with significant untapped potential due to some countries’ lowest electrification rates. Introduction of country-specific policies and feed-in-tariff system are likely to provide the required impetus for the growth of this market. The growth of this market is projected to be strong during the forecast period due to the likely introduction of feed-in-tariff in some countries, adequate solar radiation throughout the region, increasing awareness, and spur in private sector investments into this market. Solar photovoltaic (PV) systems provide the ideal environment friendly power generating solution for electrifying remote rural areas in power deficient areas of Southeast Asia as it is neither technically nor economically viable to extend grid coverage to certain isolated areas. In addition, urban end-users’ growing preference towards adopting sustainable energy solutions has accelerated the adoption of solar PV systems, particularly for roof-tops and buildings. Furthermore, strong government support through policies, feed-in-tariff schemes and other deployment programs have resulted in gradual uptake of solar PV systems both for on-grid and off-grid application. New analysis from Frost & Sullivan, “Southeast Asian Solar PV Systems Market Outlook,” finds that the solar PV systems market earned revenues of $99.6 million in 2009 and estimates this to reach $254.8 million in 2016 due to increasing awareness about environment friendly power generating technologies, global decline in prices, strong government support for renewable energy and use of solar power for rural electrification purposes.

“Favorable topography with adequate solar radiation throughout the year coupled with policies and regulations from the government are likely to expand market opportunities during the next five to seven years Southeast Asia especially in countries such as Thailand, Malaysia, and the Philippines,” says Frost & Sullivan program manager Suchitra Sriram. “The introduction of feed in tariff is expected to be a big stimulant for on-grid solar PV system installations for both distributed and centralized solar power plants.” Market trends indicate burgeoning demand owing to strong governmental commitment to the promotion of solar energy and creation of sustainable cities. However, market penetration of solar PV systems has been challenged by the high cost of installation as the majority of customers fall under the low-income group. Thus, market growth is heavily dependant on government support in terms of policy guidelines, tax credits, subsidies or rebates, until the price reaches grid parity. Moreover, the well developed power infrastructure deters the use of solar PV systems in some urban areas. The global financial crisis did not have a major impact on the solar PV systems market in Southeast Asia. However, due to the ripple effects of the financial crisis on the key global solar power markets, the economic viability of some PV projects diminished because of lack of credit from banks, financial agencies and donor countries. Another factor that contributed to restrained market momentum was the extensive use of diesel fired generator sets and other low-cost renewable energy technologies. To rev up the pace of growth of the solar PV systems market in the Asia Pacific region, it is vital for countries to establish realistic targets, streamline the policy framework, and aggressively boost customer awareness. Going forward, as production costs decline and solar PV systems gain traction, installation costs are expected to reduce and pave the way for largescale commercialization. This, in turn, will attract new entrants across the solar industry value chain. “Considering the highly competitive nature of the market, it is imperative for system integration companies to focus on enhancing growth by establishing a strong technical workforce and providing high-quality PV components,” says Sriram. “Also, participants must ensure on-time delivery of products and provide superior value-added maintenance services to outpace competition.”

Global Solar Technology – May 2010 – 19


Industry News Interview

Interview

Interview­—Matt Holzmann, Christopher Associates How does the solar industry compare with other, more mature industries that you are involved in?

Christopher Associates is a well-established distributor of equipment and materials for the printed circuit fabrication and assembly industries. Two years ago, they formed a solar division that is expanding rapidly in the United States. President and CEO Matt Holzmann talks to Global Solar Technology’s editorin-chief, Trevor Galbraith, about the unusual approach he took to the solar market and his views on the opportunities ahead.

20 – Global Solar Technology – May 2010

While new in some ways, it is also an industry that has a history going back 30 years. Polycrystalline technology has been around since the 70’s, but what is different is the scale today. The production requirements are massive. A 25 Mw plant, which is small in today’s world, produces approximately 3,000 modules per week. In technology, photovoltaic borrows many ideas from the semiconductor side and a number of ideas and materials solutions from the assembly side. A number of significant suppliers, and now solutions providers, from the electronics side have established market positions in photovoltaic manufacturing based on core competencies. From that starting point, it then morphs into an industrial scale mass production business with its own characteristics. The complexity of the photovoltaic manufacturing process does not compare to that of chips, packaging or the interconnect. In electronics, the target often changes every day. But the fundamental science, especially in thin film, is breakthrough materials technology. 2. What opportunities do you see for supplying solar equipment and materials in the United States? The North American market is, despite the best hopes of many, still in its infancy. Start-ups are still struggling, and many companies have production in the pipeline but need approvals such as UL, which can take some time. Then comes the capital issue. While agreements are being signed, they are slow in being funded. Until the money spigot is turned on and orders flow, we will see the North American industry grow in fits and starts. The industry has grown most rapidly first in Europe, and then China. In those

regions, production scales have ramped up massively and the supply chain has grown with the industry. Technology improvement and cost reduction were driven in these markets first. As we are third wave adopters, North America can take the best from the world and then improve upon it. As a supplier, we have seen solutions providers overseas, especially in Asia, committing the resources to become best in class. The economies of scale, especially in China, are driving costs down as well. The combination is formidable. Christopher Associates’ materials and equipment teams are unique as well. Our engineers complement each other and give us unique ability to do training, production line support and process troubleshooting. Maintaining the highest efficiency is critical to our customer’s profitability, and our job is to be there whenever they need us, however they need us. We are not just selling a product. We are solutions providers. 3. You referred to the solar industry as “The Wild West.” What did you mean by that? The level of expansion in this industry is explosive. We are going from 0-60 in seconds flat. There is something of a boom or bust mentality as well, as we are being challenged by external economic factors as well as our own industry dynamics. The scale of investment required and need to integrate photovoltaic into the grid are stabilizing factors, but nevertheless it reminds me of the early 1980’s in electronics when many of the great brands of today launched. A paper at the recent Shanghai show pointed out that when looking at the world’s sunbelt, the most logical market for photovoltaic energy, the surface has not even been scratched. Especially in less developed countries, PV is an optimum

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Interview

solution. When one considers the current level of market penetration of PV in China, North America, or even Southeast Asia, the market potential is daunting. 4. Do you think China will become the principal source for cell production? Perhaps, but remember, cells are fragile. A 2-3% breakage rate goes directly to the bottom line. The cell manufacturing process is also the most highly automated, so labor costs are a less significant factor, making local manufacturing more attractive. However, as we saw with the electronics packaging industry, first much of the chip business and then the substrate business migrated to countries that had a holistic infrastructure. China has a significant advantage on the module production side. Except for a few processes, Chinese module manufacturers do not use the automation levels seen in Europe, and thus have lower operating costs. But when the cells makes up 90+% of the value of a module, does this matter? Government involvement also plays a major role. Some are demanding local content. This will also play into the equation. 5. Virtually all of the equipment lines and materials you offer are sourced in Asia. Why? China is rapidly becoming the world’s largest market in photovoltaic, and Taiwan is a major center of competency in cell manufacturing. We have seen tremendous innovation and research in certain areas, and many Asian suppliers are very well funded. The combination is hard to beat. Cost is critical in the competitive equation, and Asian suppliers are rapidly becoming some of the largest in the industry due to economies of scale and the above referenced factors. 6. If solar manufacturing in the United States is going to be limited to principally module production, is there much scope for innovation at a local level? I am not quite going to buy into that just yet. It is trending that way at present, but once we see the large scale projects come on line, I think some of the factors discussed above may prompt the capital markets to fund cell manufacturing as well. On the module side, though, while there is some innovation, it is primarily a screwdriver assembly business: high

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volume, industrial-level manufacturing. North America is in a unique position to look at best practices and then adapt and innovate. The scale of manufacturing will also be critical. Smaller projects do not necessarily warrant high levels of automation. Return on investment becomes the name of the game. 7. You recently visited a large module production plant in China. How does it compare to its western counterpart? The Chinese model is very different from that of Europe. Automation is very limited, both because of the cost of labor and the advantages offered by manual and semi-automatic processes. Capital costs for a 50 Mw module plant with a high level of automation can run $12- $15 million. Running it semi automatically would have a price tag in the $3-$5 million range. There are also some interesting debates going on about yields. According to one Chinese plant manager, they felt that manual processing in some stages allowed for better alignment and attachment quality. Visual inspection in the lay up process, they felt, was a critical factor in quality control. 8. Do you think the future of the solar industry will be determined by materials science? Yes. It’s all about cost per watt and storage. Electricity is highly perishable and currently photovoltaic will do a good job at peak demand, but is limited to a percentage of the total grid capacity because of its economics and instability. By finding new processes and materials to reduce generation costs, and then align supply with demand across more hours of the day, we may be able to see photovoltaic more integrated into the grid and transcend current limitations. 9. Prices have already dropped substantially in the last recession and due to the oversupply in Spain. Do you think there will be a further drop after the German feed-in tariffs reduce in July? At present, our sources tell us that cells, backing film and EVA are in short supply in Asia and that factories are running at very high operating rates to meet the German deadline for installation. This will change in July as suppliers will have to seek new markets. However, if the American economic recovery is sustained, then we may see demand in this market begin to surge.

Other emerging markets may also pick up the slack. Short term, there are going to be peaks and valleys, but long term we should see sustained growth for a number of years. 10. You recently wrote a paper promoting the idea of a “Module Registry.” Can you explain why you think this is important? Modules are valuable commodities, and the lifetime is expected to be 25+ years. They are also electrical devices generating high current densities, with all this entails from a regulatory and safety perspective. On the manufacturing side, traceability is critical for quality control and aftermarket support. From a government perspective, building codes are affected, safety must be considered, and theft has been an issue in some areas. Insurance and replacement as the years go by must allow for traceability as well. The industry is still in its early stages, and by involving all stakeholders, a simple and inexpensive capability for an industry wide database is achievable. The technology and models are already in place. Such a matrix will contribute to product safety and the long-term interest of the industry and its customers. 11. You are holding a meeting at Flextronics, Milpitas, on June 10th to discuss the formation of a new trade association representing manufacturing professionals. Why do you think this is necessary? There are a number of trade associations that do an excellent job already, but there are few ground-level resources for the manufacturing professionals in the trenches. Continuing education, professional development, technology benchmarking, quality improvement and other issues we face on an everyday basis can be better addressed by some form of organization that is member driven on a local basis. By bringing in speakers or holding low cost seminars, we can cover core issues, take these lessons back to our companies, and become a more valuable resource. The industry is evolving rapidly and education is critical to success. Matt, thank you very much for talking to us today. Trevor Galbraith.

Global Solar Technology – May 2010 – 21


Power with a purpose

Power with a purpose Dr Keith Bowen, Circadian Solar

There’s more to solar energy than rooftop panels and solar farms. Dr Keith Bowen of Circadian Solar looks at how a combination of concentrated photovoltaics and micro-generation could provide clean, fresh water to places where it is needed most.

In Andhra Pradesh in south central India, more than 80 per cent of hospital admissions are the result of water-borne illnesses. There’s nothing particularly special about Andhra Pradesh. More than a billion people in the world today lack access to clean drinking water, and there are more people in the world’s hospitals today suffering from water-borne diseases than any other ailment. As glaciers shrink, droughts increase and salt-water intrusion spreads, the world’s current fresh water shortage is set to worsen. The Stockholm Environment Institute says that, using only a moderate projection for climate change, 63 per cent of the global population will live in countries of significant water stress by 2025. But treating water is a power-intensive and hence expensive business. It’s also one that can only become more costly as the price of fossil-fuelled electricity in social, political, environmental and economic terms becomes apparent. The world needs to find ways of cleaning, desalinating and distributing water to its citizens. And it is an area for which the use of renewable energy seems particularly apt. There is, after all, an inherent contradiction in building more carbon-emitting conventional power generation specifically to counter an issue that is dramatically worsened by climate change.

22 – Global Solar Technology – May 2010

On a more practical level, the lack of clean water is often correlated with an absence of or degradation of existing electricity infrastructure. If new power generation plant is to be built, or a serious refit programme is to be undertaken, then there is an opportunity to incorporate significant levels of renewable generation into the mix. However, to talk of renewable generation as a single entity is misleading. Wind and solar power—the most likely candidates for water treatment in noncoastal areas—are very different beasts. Even within the category of solar power

there are a myriad technologies. And each one has distinct properties that affect where and how it can best be deployed. Naturally, the prevailing weather conditions will be the major factor. There is no point in erecting wind turbines in an area where the wind is but an occasional occurrence. The reality is that the areas where availability of clean water is currently the most pressing issue, and the countries where it is most likely to become one, are best suited to solar power. In particular, concentrated photovoltaics (CPV), may prove to be the likeliest candidate for water treatment. Like other solar technologies, CPV converts the power of the sunlight into usable energy. But the advanced design of its solar cells delivers far higher energy yields than standard photovoltaics. CPV units also have an optics system that magnifies the power of the sun even further, and a sun-tracker unit so that the cells follow the path of the sun and are able to ‘harvest’ a larger fraction of the sun’s rays. The result is a system that is incredibly efficient and capable of delivering far greater levels of power from a single unit than other forms of solar electricity generation. The net result is a system that has the potential to be much more costeffective. The high levels of efficiency of CPV

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Power with a purpose

also makes it suitable for micro-generation. In the developed world, micro-generation is often seen as a well-intentioned whimsy on the part of wealthy but committed environmentalists. But in the developing world, where significant proportions of the population live in off grid rural areas or in over-crowded, unplanned urban sprawl, micro-generation has immediate and obvious benefits. Like micro-finance before it, thinking small can help solve big problems. For example, a basic micro-desalination unit—the size of an average washing machine—requires 800 watts of electricity to produce 1,000 litres a day. That’s enough for a family’s daily needs. A single CPV unit could power four of five of these machines—thus providing a cost-efficient, space-efficient and energy-efficient power source. In another example, an individual hospital might need 100-200 kw to power its own water treatment facility. In the right climate that can prove to be a more robust and more reliable source of essential clean water than an inadequate water or even electricity grid. But there are other considerations when it comes to choosing energy

sources, not least of which is support and maintenance. Systems designed for a long lifecycle and minimal maintenance are ideal. The more moving parts, the more complex its underlying engineering and the more maintenance it is likely to require. That may make it inappropriate for certain countries that could otherwise benefit. But, if you can fix a car you can fix a CPV system. So for places like India—where most small towns and many villages have a mechanic enjoying a lively trade in the repair and refurbishment of Ambassador cars and auto-rickshaws—it could be the argument that seals the deal. The deployment of renewable energy in general and CPV in particular can also support nascent tourist industries by powering the water treatment required by hotels, swimming pools and even golf courses. The water consumed by these enterprises has long been an area of concern in many areas, particularly where resources are already limited. There is a greater awareness that providing luxuries should not have an unacceptable social and environmental cost, and balancing the need to attract tourist dollars to boost the local economy and ensuring the population has its basic needs met

has not always been successful. But using renewable micro-generation to power water treatment can assist in this area. But perhaps the biggest advantage of linking technologies like CPV to very specific functions such as water treatment and desalination plant is that they make perfect demonstration projects in which the benefits of renewables can be immediately seen. In an industry that needs to boost its profile, demonstrate effectiveness and encourage greater investment, this is exactly the kind of venture that developers like. It creates something of a virtuous circle where greater investment leads to greater penetration, which in turn leads to lower costs, which encourages further deployment. There is no one easy answer to the world’s water problems. And certainly CPV does not provide the complete solution. But it does tick a lot of immediate boxes, and could play a significant role in ensuring that clean, healthy water doesn’t become the preserve of the wealthy few. But more than that, it opens the door to a whole host of other renewable energy alternatives.

The Ircon®/Raytek® Solar Advantage Customized solutions for your unique process From silicon and wafer production to photovoltaic cell and module manufacturing, we have the products you need at every step of your online process monitoring – even in hazardous and potentially explosive environments. Ircon and Raytek infrared noncontact thermometers and thermal imaging systems are designed for use in the solar industry, where monitoring and controlling temperature is critical to productivity and product quality. With a network of qualified distributors worldwide, we guarantee local support, fast service and individual application assistance. Our solutions can improve your process.

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Major Applications

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Global Solar Technology – May 2010 – 23


Flextronics ramps up solar capabilities

SNEC PV— The Shanghai Show

Mattew Holzman, Christopher Associates

The Shanghai New International Expo Center in Pudong is one of the biggest convention centers in the world and getting bigger. The construction is continuous. The 4th occasion of the SNEC-PV show covered over 900,000 square feet. The show increased in size by almost 50% from 2009 with seven temporary structures to handle the overflow from five huge halls. Over 65,000 attendees visited over 1,200 exhibitors from all over the world. SNEC-PV covered the entire range of the photovoltaic process from growing silicon to post installation services. The equipment exhibited ranged from massive polysilicon reactors to furnaces to sheet glass cleaners to module laminators to massive utility scale arrays. The scale of the Chinese industry has been underestimated. With new installations in all process steps from silicon to modules to thin film, it is by far the fastest growing market from a manufacturing perspective. There are now over 1,300 module manufacturers, some of them the largest in the world, others with one or two lines. Discussions with a number of suppliers and manufacturers indicate that business in 2010 is up by 30-40%, and that there are now shortages of wafers as well as backsheet and EVA films. While module prices decreased because of a glut in 2009, it seems that prices are firming and companies are expanding production capacity at a rapid rate, primarily for export markets. There has been a trend towards outsourcing by a number of Western module suppliers which has benefitted the Chinese industry. At the same time, domestic consumption is growing rapidly. The combination of factors will lead to explosive growth in this market over the next few years. China is based primarily around mono and polycrystalline cell technology. Thin film is still in its infancy. One interesting concept on the thin film side was that

24 – Global Solar Technology – May 2010

of a Chinese-American company called General Solar Power, who developed their technology in North America and the equipment set in China. They advertised an installed cost of equipment at US$

0.80/watt. All of the major turn key suppliers had large presences as well and were very optimistic about the growth of utility level and building integrated (BIPV) photovoltaic applications in China which will require large scale thin film factories over the next several years. The advances in cell manufacturing exhibited at the show were incremental. Higher productivity and higher yields were the key takeaways. Not much was heard of thinner cells, but there was significant emphasis placed on larger and more efficient reactors, superior dicing technology, and higher processing speeds. Several companies advertised nanopastes to improve transfer efficiency and electrical transmittance. The Chinese module manufacturing industry still relies upon the West for much of its manufacturing technology, but not for much longer. Localization is a theme that runs through the entire Chinese industry. The Chinese manufacturing model combines manual and semi-automatic processing even in Gw scale factories. Factories are arranged around “units” each operating semiautonomously to achieve 25-50 Mw/year capacity. Almost all of these factories are operated using manual or semi-automatic processes using the assembly line model common in other industries. This offers a significant capital cost advantage that must be scrutinized carefully when analyzing cost per watt of finished product. The technical conference was held at the Shanghai International Convention Center, several kilometers from the exhibition. After welcome speeches from Mr. Yi Ren Jiang, member of the Standing Committee of the CPPCC and from the Shanghai Science & technology Commission, keynote speeches were presented by industry experts from around the world. One theme noted by several speakers was the political nature of the photovoltaic

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Giving your metallization process the “OK”

industry in the European Union. It seems there is a concerted effort to raise the costs of competitive technologies to make photovoltaic energy more attractive. This is in conflict with the reduction of feed in tariffs in Germany, Spain and elsewhere occurring this year. Dr. Murray Cameron of Phoenix Solar noted that globally, the industry will achieve maximum efficiency with 5-6 Gw of annual capacity distributed globally. Sr. Ernesto Macias of the Alliance for Rural Electrification emphasized the requirements for and significant advantages of photovoltaic energy in the global sun belt, where penetration of the industry is almost nonexistent. While containing a significant proportion of the world’s population, many of those countries are the best candidates for large scale photovoltaic electrification because of the lack of existing infrastructure and need for distributed power generation over large areas. Prof. Martin Green of the University of New South Wales summarized developments in thin film technology. He began by pointing out that with time, $1.00/watt for poly/monocrystalline modules is a realistic goal. He then outlined the progress in CdTe, amorphous silicon, CigS, and CSG technologies, as well as some of the challenges, especially on the environmental side. He was optimistic that research into printed cells, plastic cells, dye sensitized cells, and

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quantum dot cells will drive technology to higher efficiencies and lower costs in coming years. Dr. Mark Pinto discussed the impact of power plant level photovoltaic on the Chinese grid with a discussion of peak demand grid loading and management. The potential for large scale efficiencies and reduced cost per installed watt was said to offer an effective solution as energy requirements continue their steep rise. Part of the rise in demand for photovoltaic on Europe, as Dr. Henning Wicht of iSuppli noted, is the phase out of German subsidies expected this summer. His report on the global market estimates a

50% growth rate for 2010 but with a high level of volatility constrained by the lack of installation infrastructure. He noted that spot prices for modules are rising and expected a 10% rise in 2011. There was significant interest in the presentation by Chris O’Brien of the U.S. SEIA on the potential for the North American market. With approximately 430 Mw installed in 2009, he predicted significant growth in 2010 with a surge in 2011. At present, capacity within the North American manufacturing base cannot meet demand. He noted 6.5Gw in utility scale projects in process as well. Separate tracks for CEO, CTO, materials, and grid connection were discussed in break out sessions in the afternoon. Topics discussed on the second day focused on thin film, cross Straights business, cell manufacture and test, and module manufacturing. The photovoltaic industry is rapidly evolving and the only constant is change. China is rapidly becoming the largest market in the world through both domestic and export consumption. Attendance by Western visitors was limited to a small percentage of the total. With the explosive growth of the Chinese photovoltaic infrastructure, next year’s show, in February, should be interesting indeed.

Global Solar Technology – May 2010 – 25


New Products Title

New products

Christopher Associates introduces new cut sheet laminator Christopher Associates Inc. introduces the CSL-A25T Cut Sheet Laminator from C Sun Manufacturing Company. C Sun, Asia’s largest manufacturer of imaging, curing, and photo resist lamination systems, developed the CSL-A25T for flexible and thin core substrates. With the capability to laminate substrates up to 25” wide and from 0.05 mm-3.5 mm thick, the CSL-A25T offers the flexibility necessary for today’s manufacturing environment. www.christopherweb.com OK International launches enhanced PV tabbing and bussing soldering systems OK International has launched a new soldering system for PV tabbing and bussing applications proven to reduce micro cracking. The PS900 with specially designed hoof tip geometry optimizes the power delivered to the solder joint while its temperature-sensitive heater ensures low temperature soldering, thus minimizing thermally induced stresses on cell surfaces.

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The PS 900 incorporates OK International’s patented SmartHeat® Technology that will produce and maintain a specific, self-regulated temperature with a heater that requires no calibration and responds directly to thermal loads. There are two suitable solder alloys utilized for solar cell soldering application; Sn96Ag4 with a melting point of 221˚C, or bismuth containing Bi58Sn42 with a melting point of 138˚C. Proper soldering will result in an intermetallic layer that is 1-2μm, which demands precise time and temperature control during the solder joint formation. “The ability to solder at low, controlled temperatures within a short time widow reduces the stresses on the cells and the likelihood of micro cracking,” explains Hoa Nguyen, VP of Technology. “Connection temperatures must be maintained below 300˚C.” Micro cracking of delicate solar cell substrates is a common defect that can occur during PV tabbing and bussing soldering processes. Reducing the soldering temperature to a minimum prevents the cells being subjected to mechanical or thermal stresses. During the soldering operation, differential thermal expansion of the copper and the silicon elements can occur at temperatures greater than 300˚C. This differential can result in the formation of micro-cracks that may not be detected during the manufacturing process and result in reduced field lifespan. The OK International SmartHeat PS-900 soldering system with specially designed STVDRH40 hoof tip geometry optimizes the power delivered to the solder joint, thus providing high performance efficiency with increased tip life. www.okinternational.com

free Copper C10100 (OFE / CDA-101) at 99.99% purity, the base copper, ribbon can be can be ‘half hard’ for greater tensile strength or ‘dead soft annealed’ for enhanced flexibility and elongation under tension. For customers requiring a lead containing, fused alloy coating there are tin/lead and tin/lead/silver combinations but, akin to the electronics assembly industry, many panel assemblers are already using or considering lead-free options. Currently, the most popular lead free coating is tin/silver but Cookson’s proprietary lead-free tin/silver/copper alloy (SACX® 0807) is fast becoming an acceptable alternative. Designed to deliver maximum value and processability, SACX® 0807 maintains solder joint reliability while delivering real savings thanks to its lower silver content. Compatible with standard tabber/ stringer assembly soldering systems, ALPHA® PV RIBBON™ is available in a variety of widths: 1.5mm, 2.0mm, 2.5mm and 4.0mm, with other sizes made to order, on both 4kg and 5kg reels. www.alphapv.cooksonelectronics.com

Cookson Electronics launches ALPHA PV Ribbon™ for solar module assembly Cookson Electronics Solar Materials’ new range of solder coated copper ALPHA PV RIBBON™ for solar panel assembly has been shown to provide excellent, repeatable pull strength due to the close control specification of the base copper and the exceptional uniformity of the even, high solderability coatings. Available in Electrolytic Tough Pitch Copper (ETP 110) 99.9% pure and Oxygen

Creative Materials introducing electrically conductive epoxy family of adhesives Creative Materials, Inc., introduces superior two-component conductive epoxy adhesives that are easy to use and offer excellent conductivity and bond strength. The new family of electrically conductive epoxy adhesives includes 118-15, 123-39, 124-08 and 125-18. These products are 100% solids silver-filled epoxy systems, designed for attachment of electronic components. Applications include

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New Products

mounting of LEDs, chip attachment, solar cell assembly, metal to glass bonding, attachment of leads, and lid attachment. With excellent rheological properties, these products are dispensible via syringe or using high-speed jet dispensing systems, allowing dispensing in dots or lines as narrow as 1 to 3 mils. The products in this epoxy family share many of the same characteristics, each featuring some key advantages. All are available as twocomponent (A/B) systems or as singlecomponent precatalyzed (C) products. www.creativematerials.com Multipurpose bondtester tests ribbon interconnects, conductis peel tests Nordson DAGE, a subsidiary of Nordson Corporation, is leading the way in solar cell and panel testing to assure the mechanical integrity and guarantee performance. The Nordson DAGE multiple purpose bondtester uses standard accessories to test both the ribbon interconnects on the photovoltaic cells as well as conduct peel tests on whole sections of panel. The large working envelope of the Nordson DAGE bondtester is ideal for testing large sections of solar panel, with its specialized fixtures designed to handle the large area arrays without damaging them. “Our solutions for solar testing cater for the specific test requirements,” said Phil Vere, managing director bond testers for Nordson DAGE, “and offer unrivaled accuracy and repeatability of data, providing complete confidence in results.” www.nordsondage.com BioSolar expands line of BioBacksheets for PV module manufacturing in various grades BioSolar, Inc., developer of a breakthrough technology to produce bio-based materials from renewable plant sources that reduce the cost of photovoltaic solar modules, announced plans for an extended line of BioBacksheets to protect PV modules compatible with conventional c-Si PV modules. Conventional c-Si photovoltaic (PV) module manufacturers will soon have two different types of BioBacksheets to choose from depending on their durability and cost requirements: 1) a multilayer BioBacksheet-C for conventional applications and 2) a new mono-layer BioBacksheet product line for premium applications. These products were developed to meet the existing and future direct needs of potential customers.

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The announcement represents the latest addition to a broad and growing portfolio of bio-based backsheet materials made from renewable plant sources that reduce the cost of solar modules and eliminate the need for dangerous toxins found in petroleum-based backsheets currently in use. www.biosolar.com V-M.O.L.E.® solar profiling kit ECD announced its formal entry into the solar market with the introduction of the V-M.O.L.E.® solar profiling kit. This kit, designed for the metallization process of photovoltaic solar cells, is currently in use at research institutes, oven OEMs and live production areas.

Solar device efficiencies are a result of the metallization process and are driven by process parameters of hold time (dry time), firing cycle ramp rate, peak temperature, and cool-down rate. Designed for ease and speed of use, the V-M.O.L.E. solar profiling kit combines patented and proven elements of legacy profilers with adaptations for metallization’s special requirements. It comes with the V-M.O.L.E. thermal profiler, the special solar thermal barrier, which is only 0.7” (18 mm) in height, MAP software, and special thermocouples, all of which are necessary for measuring and assuring that the key profile parameters are being met. The patented OK Button allows for faster results from the profiling process. www.ecd.com Charcoal Protekt Backsheets by Madico – The ideal solution for building integrated photovoltaics Charcoal Protekt is a high performing PV backsheet with aesthetically pleasing characteristics, boasting a dark, discrete appearance that makes it an ideal solution for the building integrated photovoltaic

(BIPV) sector. The industry-first charcoal coating for PV backsheets blends into the module and integrates seamlessly in virtually any home or building. Charcoal Protekt is available in Protekt HD and Protekt TFB HD. Charcoal Protekt HD uses a high performance film coating in a special process that when applied to the base dielectric bonding layers of PET/ EVA, resulting in a laminate with excellent stability characteristics for vacuum laminating processes and outdoor use. The Charcoal Protekt TFB HD uses a layer of aluminum foil, which provides optimal barrier properties, making the product ideal for thin film technologies. The “HD” version uses thicker PET and meets IEC 60664 standard for 1,000 VDC. www.madicopv.com High-speed spatial atomic layer deposition (ALD) Dutch research organization TNO has developed a novel disruptive concept in atomic layer deposition (ALD), with breakthrough ultrafast deposition rates of 1 nm/s for Al2O3. Using spatial ALD, instead of temporal (i.e. time-switched) ALD, TNO researchers deposit 30 nm of Al2O3 in 30 seconds. Compared to 20 minutes in an R&D single-wafer reactor, this opens up a wide range of industrial-scale applications with high industrial throughput and cost-effective manufacturing. One new application is to improve solar cell efficiency by depositing Al2O3 as a backside passivation, or as an encapsulation layer. Other applications are as barrier layers for OLED, buffer layers in LED technology, and more. TNO is currently working on the development of an in-line industrial ALD tool for high-volume production. The spatial ALD tool for passivating Si solar cells is designed to produce up to 3,000 wafers per hour. This mass production possibility opens up a diversity of applications, and will generate more business for organizations in many different markets. www.tno.nl Precision Process Equipment introduces FSP cleaning system To compliment Precision Process’s Flexible Substrate Plating (FSP) line of products, the company is introducing the FSP Reel-to-Reel Cleaning System. This continuous coil-to-coil cleaning system can be configured to handle strip widths from 25 mm to two meters wide at speed up to 100 meters/min. It is available for stamped strips, wire, and tubing applications as

Global Solar Technology – May 2010 – 27


New Products

well. Precision Process’s inline continuous strip cleaning system accommodates the use of environmentally safe, aqueous cleaning solutions for cleaning operations that need to remove chips, oils, and coolants from rolled strip material. The modular designed cleaning system is easily configured to your requirements. Along with standard wash, rinse, and dry options, supplementary stations can be added for specialized features including but not limited to: ultrasonic cleaning, high pressure spray wash, and spot-free drying. www.precisionprocess.com 1366 Technologies teams with RENA to unveil high-efficiency cell process 1366 Technologies has partnered with RENA to incorporate 1366’s Self-Aligned Cell technology into a complete cell production process. The new highefficiency silicon cell process will integrate 1366’s proprietary structured patterning technology with RENA’s wet processing technology. “Integrating 1366 Technologies into our existing process clusters will provide customers with higher-performing cells,” said Hartmut Nussbaumer, managing director of RENA. RENA’s current product line includes the market-leading InTex wet processing system for texturing wafers. The addition of 1366’s proprietary honeycomb-structured texture to the cell production process will yield a significant improvement in absolute cell efficiency. The texture can be used on both mono-crystalline and multi-crystalline wafers, giving cell manufacturers previously unattainable flexibility. www.rena.com, www.1366tech.com Schmid Group tastes success with new the selective emitter technology

One of the main sources of potential loss in the case of solar cells industrially manufactured on the basis of crystalline silicon is due to the high rate of phosphor doping on the sun-facing side, the emitter. With its innovative, wet-chemical etching technology, Schmid has created a selective emitter structure in which the recombination currents could be

28 – Global Solar Technology – May 2010

significantly lowered and the efficiency of the solar cells greatly increased. Numerous trials carried out at their own technology centre together with additional tests and reports published by their research partner, the University of Constance, prove that the efficiency of multi-crystalline wafers has been increased by 0.4 % and that of monocrystalline wafers by 0.8%. Up till now, two high-temperature processes were usually necessary for the manufacture of a selective emitter. This put a thermal strain on the wafers, impairing both the mechanical and electrical quality of many substrates. With this newly developed technology it is now possible to produce a selective emitter using a simple printing method on an Inkjet printer DoD ProSeries (Schmid’s own development) and a subsequent simple etching technique in a Schmid Inline system, without the wafers being subjected to increased thermal strain. With this digital Inkjet printing technology and the use of optical characterisation techniques it is possible to guarantee outstanding precision and process stability. This new wet chemical etching technology makes it possible to etch the surface of the wafer at an accuracy of just ten atomic layers and thus guarantee a very homogenous quality of the n-conducting layer. This method is by far the most simple technology for manufacturing a selective emitter structure. It caters for great stability in production and can be retrofitted in existing production systems with very little effort. www.schmid-group.com Bluestar Silicones launches a new range of products for solar applications Bluestar Silicones is launching a new range of solar application products, including a new high performance adhesive, CAF(R) 530, that optimises the longevity performance of solar modules. Bluestar Silicones is also launching a new range of silicone products that will increase the efficiency and longevity of solar modules by extending their resistance to weather erosion under conditions where

performance must be constant for at least 25 years. This new range includes mono and bi-component silicone elastomers (RTV 1 & 2) designed for sticking and sealing the frame and junction box as well as bi-component products designed for the encapsulation of components in the junction box and of photovoltaic cells. The range, specifically adapted to the assembly of solar modules, includes high performance products, such as high performance adhesives on multiple substrates used by the profession, encapsulation agents with dielectric and exceptional fire resistance characteristics and transparent encapsulation agents for photovoltaic cells with very high levels of optical transmittance. www.bluestarsilicones.com AMETEK’s TerraSAS solar array simulator enhances micro-inverter testing The Elgar brand TerraSAS Solar Array Simulator from AMETEK Programmable Power offers a fully integrated solution for the design, development and production testing of inverters and micro-inverters for domestic and industrial solar energy systems. The TerraSAS simulates photovoltaic (PV) dynamic solar irradiance and temperature characteristics over a range of weather conditions from clear to cloudy and over a specified time interval to produce the current / voltage (IV) characteristics for the specified PV array for those conditions. For ease of use, the system’s simulation engine is able to download data from the National Renewable Energy Laboratory (NREL) Solar Advisor Model database defining key parameters so that the IV curve can be calculated according to a standard solar cell model for virtually any fill factor or solar material. Other PV panel IV curves can be entered manually. Systems with multiple panels with different characteristics resulting in “multiple hump” IV curves also can be simulated. In addition, the TerraSAS is capable of simultaneously simulating up to 24 parallel channels for use with micro-inverters. www.programmablepower.com Atlas adds coastal/marine option to the Atlas 25PLUS™ pv module durability test program In response to customer feedback on evaluating the effects of salt corrosion on photovoltaic modules used in seaside installations and marine applications, Atlas Material Testing Technology has added a

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New Products

coastal/marine test option to the Atlas 25PLUS PV module durability testing program. This new option may be added to either the standard “Global Composite” or “Tropical/ SubTropical” climate tracks of the test program. The coastal/marine option adds an additional PV module to the standard test program and extends the total test time from twelve to thirteen months. The additional module is exposed at the Atlas sub-tropical, South Florida test site where standardized synthetic seawater is applied via spray five days a week to the front and back of a nearhorizontal module. Furthermore, the laboratory accelerated aged module from the standard 25PLUS program undergoes an additional final month of salt fog and condensing humidity chamber exposure. These added stresses provide data on the effects of saltwater exposure on both new and severely weather-aged modules for data comparison to the non-saltwater exposed performance. www.atlas-mts.com ECM rolls out new Sol-Ag product line of electrically conductive interconnect adhesives Sol-Ag Series interconnect adhesives were developed to exhibit “rubber-like” flexibility, that reduces stress in the interconnect bond line, imparts resistance to thermal cycling and increases overall peel strength of the assembly. In addition to flexibility, Sol-Ag Series excel in accelerated damp heat conditions when tested to IEC standards. Sol-Ag Series also has demonstrated unchanged electrical performance after 1000 hours at 85C/85RH on tin-silver and copper surfaces. By providing stable contact resistance to non-noble metals with “rubber-like” flexibility the SolAg Series interconnect adhesives will satisfy the rigorous performance and reliability requirements for the thin film and potentially c-Si industries in the years to come. www.emsadhesives.com DEK Solar reveals range of enabling technologies for specialist PV applications DEK Solar has revealed a range of technologies designed to provide advanced support for specialist photovoltaic applications. One such solution is the 248 semi-automatic screen printing platform, equipped with a range of advanced features to enhance solar cell production including programmable machine parameters, castings and precision machine-tool bearings for high levels of accuracy and repeatability. Other DEK Solar technologies for specialist PV applications include Reel-to-Reel (R2R), an advanced handling solution for continuous, flexible solar substrates. R2R uses proven precision alignment, clamping and tooling technologies to handle the demands of large, flexible substrates. Featuring inbuilt accurate positional indexing and tension management mechanisms, R2R prints onto substrates typically up to 150 metres in length and 500mm wide. Minimising stress and preserving the condition of the substrate, R2R’s robust motion control and substrate clamping techniques enable step-and-repeat sequences for maximum control and minimum waste. www.dek.com

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joint World Conference of:

Global Solar Technology – May 2010 – 29


Increasing solar panel production efficiencies with acrylic foam tape

Increasing solar panel production efficiencies with acrylic foam tape Rick Traver and Brent Ekiss, Fabrico, Kennesaw, Georgia, USA

Solar manufacturers are always working toward grid parity. With grid parity, the cost of generating a kilowatt of energy from solar will be equal to the cost of generating a kilowatt of energy from fossil fuels. With fossil fuels at approximately $0.04/kWh and solar averaging around $0.50/kWh, there’s still considerable ground to be made up.

Solar manufacturers are always looking at ways to make solar technology more efficient while reducing manufacturing costs and increasing the working life of solar panels. Implementing automation and reducing materials costs are critical goals. A key part of the process is selecting materials that can meet manufacturing process needs and lifecycle requirements. In the areas of edge sealing, frame bonding, and junction box mounting, manufacturers now have the ability to

increase productivity, improve quality and increase the effective lifecycle of solar panels by using high strength, acrylic foam tapes. Edge, frame and junction box Whether working with crystalline or thin film solar technology, manufacturers need to address edge, frame (for rigid panels) and junction box attachment and sealing. For rigid, crystalline solar panels, a frame provides protection, stability, and a

Keywords: Edge Sealing, Frame Bonding, Junction Box Mounting, Acrylic Foam Tape

Figure 1. Rigid silicon.

30 – Global Solar Technology – May 2010

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Increasing solar panel production efficiencies with acrylic foam tape

structure for installation. Thin film panels don’t use an actual frame but typically use a back pane of glass and a backrail as a carrier system. Both technologies require an edge seal to protect against moisture and the effects of heat and wind. Junction boxes are mounted on the back or top of the panels and provide the connection to capture the energy from the panel. Obviously, it is critical that the electrical contacts within the junction box be protected from water. Traditional metal joining technologies have proven to be costly, time-consuming, and not completely effective for the solar industry. Mechanical fasteners, such as rivets and spot welds, have been replaced by adhesive technology in many areas within solar manufacturing. There are several advantages to using adhesives in solar panel manufacturing: • Uniform distribution of stress eliminates stress concentration • Weight reduction of bonded parts • Ability to bond dissimilar materials • Compensation for different expansion and contraction rates • Improved resistance to shock and vibration • Improved resistance to peel forces • Excellent sealant characteristics against environmental conditions In solar panel manufacturing, bonding, joining and sealing technology must be able to withstand extreme environmental conditions while providing an expected 25 to 30 years of service life. Expectations for any adhesive materials used in these applications include the following capabilities: • Provide an effective moisture barrier to protect the solar panels and electrical connections • Are non-conductive in order to avoid shorts • Provide UV stability • Resist changes in heat and cold In addition, manufacturers are also concerned with how fast any adhesive cures. Curing time can have a direct effect on the production process. For many years, solar manufacturers have turned to adhesive tape as sealants for solar panels. Polyethylene and polyurethane tapes have been popular in the solar market for more than 20 years. Now these tapes are joined by acrylic foam tapes as possible solutions for solar application challenges. In addition to tapes, manufacturers are also looking at silicone adhesives, like

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Figure 2. Thin film.

epoxies, for use in these applications. Silicone adhesives Silicone adhesives certainly meet the requirements for strength, durability, lasting bonds and resistance to moisture. Silicone adhesives are popular materials in solar applications. They provide: • UV stability and moisture resistance • Durability and solar radiation resistance • Excellent electrical insulating properties • Operation across a wide temperature range from -40˚C to 150˚C • Excellent adhesion to glass and photovoltaic substrates

The use of these adhesives often requires an investment in dispensing technology, as well as careful balancing of strength versus curing time. For example, most manufacturers might have a panel coming off a production line at the rate of one per minute. The next step would be to dip and leak test the panel. This might occur within three to four minutes. The curing time for any adhesive used would ideally be within this very short time frame, in order to keep production moving. If it were necessary to wait a period of

time for curing to be completed, panels would pile up before testing. In addition to slowing down production, the effects of discovering a problem during delayed testing might mean hundreds of panels could be rejected and scrapped. Polyethylene and polyurethane foam tapes Polyethylene (PE) and polyurethane foam tapes have long been used by solar manufacturers for edge and frame sealing and for attaching junction boxes. These tapes are made in different grades and thicknesses. Typical thicknesses are 0.8 mm, 1 mm and 1.55 mm, with a thickness on tolerance of +/- 20%, normal for a blown foam. PE foam tapes are coated on both sides with adhesive using a transfer lamination process. The foam is corona treated so the adhesives will key into the foam. The transfer lamination process gives a variance as to the performance of the tape. The quality and consistency of the corona treatment of the foam and the control on the lamination process can affect tape performance. Delamination of the adhesive can occur when these processes are not controlled properly. PE foams are available in tape form

Global Solar Technology – May 2010 – 31


Increasing solar panel production efficiencies with acrylic foam tape

in densities from 33 kg/m3 to 200 kg/m2. The normal density for tapes of 0.8 mm to 1.5 mm thickness is 67 kg/m3. PE tape is very useful in applications where gap filling is required and the bond is not subjected to a lot of stress. PE tapes are easily applied and can fit well into the typical solar panel manufacturing process. They are also cost-effective materials. The compressive strengths of the foams, however, are low. Cell rupture can occur with very little force and foam cells do not recover well from compression. The internal cohesive strength of the foam is poor and tears can occur. Flex strength during elongation and maximum static load are also low. When subjected to repeated expansion and contraction due to high and low temperatures, and used with different materials like glass, aluminum, and plastic, the foam will degrade and breakdown over time leading to leakage and water absorption. There have been issues with PE foam tapes in solar applications where the foams fail after eight to nine years of service life. Selecting the appropriate materials is a critical decision for solar manufacturers whose products are expected to last longer than 25 years. Acrylic foam tape High strength acrylic foam tape provides an attractive alternative for solar applications. Acrylic foam tape has been around for more than 20 years, although it is only now being applied to a broader range of applications. For example, acrylic foam tape is used for sound dampening and application of graphic materials in commercial vehicles, bonding and sealing in electronics, strong and durable bonds

for exterior signage, and bonding of architectural panels in construction. The acrylic looks and feels like foam but is acrylic with air bubbles and glass beads injected into it. It also gives the tape a viscoelastic effect which will stretch and retract to its original shape without breaking the bond. This provides the excellent expansion/contraction capabilities necessary for solar use without any adhesion loss. The tapes have excellent load bearing characteristics with conformability, high tensile strength, high shear and peel adhesion, resistance to plasticizer migration and UL 746C recognition. Acrylic foam tapes also have excellent durability as well as solvent and moisture resistance. Relative shear strength is very high, adhesive strength tensile N/cm2 is 110, with an adhesive strength 90˚ peel N/10 mm of 35.0. Standard slitting tolerance is +/- 1/32 inch (0.8 mm) with precision slitting tolerances of +/- 1/64 inch (0.44 mm). The tape can be die-cut in limitless shapes and sizes. They can resist very high wind forces and snow loads. In addition, they are more than capable of withstanding very high UV exposure for long periods without degrading or discoloring. Unlike PE foam tapes, they withstand temperature extremes—minus 40˚C to plus 160˚C. In addition to their environmental capabilities, acrylic foam tapes deliver moisture, dust, and air sealing for frame bonding, edge sealing and junction box mounting. The tape can be precision die-cut for use as a gasket for a wide range of junction box sizes and shapes. It bonds well to polycarbonates, PPE and other

thermo-plastics. For frame bonding and edge sealing, acrylic foam tape has strong bonding characteristics with aluminum, glass, and backing films. The tape adheres to both high surface energy (HSE) and low surface energy (LSE) substrates. LSE surfaces— typically plastics—are essentially “non-stick” plastics, like Teflon, that don’t adhere well to other materials. Some acrylic foam tapes adhere to LSE surfaces without surface treatments or primers, resulting in faster production and assembly. In thin film production, the acrylic foam tape is used with reinforcing backing rails to support the modules and make module mounting easy. Eliminated curing time allows manufacturers to keep the production line moving—there’s no need to wait for liquid adhesives to cure. Dip tank Hi-pot testing can be performed immediately. Other cost advantages include: • Faster assembly process • Reduced re-working • Lower labor costs • Cost-effective tape Finally, unlike PE foam which is a solvent-based adhesive, the acrylic foam tape is environmentally friendly. A fact that will become increasing important as pressure increases to make solar panel manufacturing greener. The selection of the appropriate edge, frame, and junction box sealant technology will always depend on the specific manufacturing process. Acrylic foam tapes offer new possibilities for protection and moisture resistance that can also increase manufacturing productivity.

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Volume 3 Number 5 May 2010

Southeast Asia

News for the Solar Manufacturing Industry

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

Matt Holzmann Interview inside

A prActicAl guide for improving crystAlline solAr cell efficiencies through firing process optimizAtion

NEW PRODUCTS

smArt pAckAges for cpv cell devices

INDUSTRY NEWS INTERNATIONAL DIARY

increAsing solAr pAnel production efficiencies with Acrylic foAm tApe

32 – Global Solar Technology – May 2010

We’re growing

Spring 2010

May 2070

Global Solar Technology magazine

Achieving thermAl uniformity in photovoltAic ApplicAtions

Gloabl Solar Technology Southeast Asia Volume 1 Number 1

Gloabl Solar Technology Volume 3 Number 5

www.globalsolartechnology.com

News for the Solar Manufacturing Industry

Transfer Transfer prinTing: prinTing: an an emerging emerging Technology Technology for for massively massively parallel parallel assembly assembly

China South East Asia The World

converTing converTing consideraTions consideraTions for for flexible flexible maTerials maTerials maTerials maTerials and and The The growTh growTh of of pv pv Technology Technology

K Subramanya Column Inside NEW PRODUCTS INDUSTRY NEWS INTERNATIONAL DIARY

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28–30 July Hyderabad International Convention Centre, Hyderabad, India

India’s Largest Solar Focused Exhibition & Conference SOLARCON® India is the original solar-focused event (exhibition/conference) in India and the conference program features the world’s leading experts in solar technology, manufacturing, markets, applications, finance and policy. Expands on the success of SOLARCON India 2009 Supported by Key Indian Solar Industry Leaders Advances the goals of the Jawaharlal Nehru National Solar Mission Meet, learn, interact, and network with leading solar experts, innovators, industry leaders and policy makers from India and around the world

Presentations from the World’s Leading Solar Experts • Dr. Winifred Hoffman, Applied Materials & European Photovoltaic Industry Association (EPIA) • Paula Mints, Navigant Consulting • Dr. Chandra Khattak, GT Solar • Dr. Jurg Henz, Oerlikon Solar • Dr. Simone Arizzi, Photovoltaic Solutions and many more… SOLARCON India—run by the solar industry in India for the industry in India.

Plan now to attend SOLARCON India 2010! www.solarconindia.org


Title

Maintenance-Free Dispensing The TS5000DMP valve provides accurate and repeatable dispensing for various manufacturing processes:

• Dispense silver epoxy for stringing cells • Dispense solder paste in tabbing process • Linking terminal bus bars of multiple cells Techcon Systems offers a complete line of precision fluid dispensing equipment for the renewable energy industry. Contact: www.techconsystems.com 1-714-230-2398

Fluid Dispensing Valves 34 – Global Solar Technology – May 2010

Valve Controllers

Dispensing Syringes

Dispensing Tips

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Global Solar Technology #3.5 - May 2010