Global Solar Technology July/August 2010 (3.7)

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The Global Journal for Solar and PV Manufacturing Professionals

Volume 3 Number 7 July/August 2010

Turning CIGS thin film into actual solar collectors—a critical step The effect of the firing process ON the energy conversion efficiency of solar cells Novel thin-film crystalline Si solar cell approaches Performance chemicals in cell manufacturing

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Contents

Volume 3, Number 7 July/August 2010

2 Editorial

Alan Rae

6

Technology Focus

6

Turning CIGS thin film into actual solar collectors —a critical step Colin Weightman, Comco Inc.

10 The effect of the firing process on the energy conversion efficiency of solar cells

Ben Sun, Heraeus Materials Technology Shanghai LTD, and Crystal Han, Topsola, Shanghai 12 Novel thin-film crystalline Si solar cell approaches

Mieke Van Bavel, Ivan Gordon, and Valérie Depauw, Researcher, imec, Leuven, Belgium

10

16 Performance chemicals in cell manufacturing

Johan Hoogboom, Suzanne Kuiper, Paul Thomassen, Mallinckrodt Baker BV

14

Special Features

17 18 20 34

Mallinckrodt Baker interview Innovation from wafer handling to panel installation Interview—Hansjoerg Lerchenmüeller, Concentrix Solar Higher efficiency in solar technology

Regular Features

4 22 24 26 40

Industry News Technological Developments Analyst Buzz New Products Events Calendar

16

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

Equipment supplier Oerlikon Solar is the main sponsor of the Oerlikon Solar Racing Team participating in the Zero Emissions Race with its Zerotracer electric vehicle. (p. 2)

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Global Solar Technology – July/August 2010 – 1

Editorial

Dr. Alan Rae

Editorial Offices

Europe Global Solar Technology Trafalgar Publications Ltd Unit 18, 2 Lansdowne Crescent Bournemouth Dorset, BH1 1SA 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: +1 (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) 245-9264 x101 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 x106 subscriptions@globalsolartechnology.com

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Technical Editor, Global Solar Technology

Intersolar San Francisco has come and gone. Three floors of enthusiasm at Moscone West, and traffic seemed significantly up from last year. We saw lots of process companies, some clever product innovations (I particularly liked the combination of solar and thermal panels to raise overall energy capture efficiency) and a strong representation from the growing solar industry in China. What I didn’t see were any real breakthroughs— silicon continues to dominate for most applications (although CIGS and CdTe are proving to have real legs). Further evidence of this domination came after the show with the announcement by Applied Materials that they would discontinue sales of their integrated lines for manufacturing thin-film solar panels.

Vendors to the industry and proactive solar system companies are not standing still, however, as we wring every performance and cost advantage we can out of the processes. I had a chance to talk in detail with several companies who exhibited at Intersolar and at Semicon West. In performance chemicals, Mallinckrodt-Baker discussed their formulated performance chemicals for texturing and emitter optimization, which can make significant improvements in cell performance. Edwards High Vacuum reviewed the systems necessary for producing reliable high vacuums when pumping air or other gases containing corrosive or particulate contamination.

Bosch Rexroth showed clever automated handling systems designed to lower production costs while protecting fragile cells. And Concentrix Solar announced the opening of their North American subsidiary and reviewed their highperformance CPV modules. CPV has

some really interesting economics for hot and arid areas and the Concentrix Solar products have some unique benefits.

It will be interesting to see how the show evolves as the US market evolves.

At the risk of oversimplification, the US market is heavily biased towards the utility/municipal and industrial markets without the level of consumer activity seen in Germany or Canada. This means the market has a very different dynamic and timescale (but may have many similarities to the evolving China market?) When we get an energy bill in the USA (and it looks highly unlikely this will happen before the November elections) it will be really interesting to see how this emphasis shifts.

At the local level, states and utilities (both of whom who have an interest in increasing their renewable portfolio) are working to stimulate activity .In the Buffalo area (which is actually at about the same latitude as Spain or Italy) I’ll be talking at the “Business of Energy” workshop “Photovoltaics and Beyond” arranged by the Directed Energy program in Amherst, NY, on Wednesday, September 15th (www. nydirectedenergy.org) . This program is funded by NYSERDA, the New York State Energy Research and Development Authority. We saw how important networking and information sharing could be in the “Solar America Cities” article recently, and it’s great to see local events like this springing up.

So enjoy the peak solar days, those of you in the Northern Hemisphere, and enjoy this information-packed issue!

—Alan Rae, PhD

From the cover: Oerlikon Solar is the main sponsor of the Oerlikon Solar Racing Team, participating in the Zero Emissions Race with its Zerotracer electric vehicle. The Zero Emissions Race is the brainchild of Louis Palmer, the first person to circle the globe in a solar-powered vehicle. Palmer’s aim with the Zero Emissions Race, which is being held under the auspices of the United Nations Environmental Program (UNEP), is to present emissions-free mobility solutions. The Zerotracer, sponsored by Oerlikon Solar under the auspices of Cleantech Switzerland, is one of these solutions. The Zero Emissions Race will start on August 16, 2010 at the United Nations office in Geneva and will continue for 80 days, heading eastward through 16 countries and passing through more than 150 cities before concluding on January 22, 2011 in Geneva. For more information about the Zerotracer, visit www.zerotracer.com. For more information about the race, visit www.zero-race.com.

2 – Global Solar Technology – July/August 2010

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Industry news

Industry news QuantaSol restructures in gear-up to volume manufacture QuantaSol Ltd has undergone significant restructuring as it readies for volume manufacture of its single-junction device that was shown to achieve a recordbreaking 28.3% efficiency. Ivor Thomas joined the company as chief financial officer, bringing extensive experience from within several UK listed technology companies. Dr Gianluca Bacchin joined as VP of engineering. His previous positions include product development director at Intense Ltd and senior researcher/engineer at Corning OTI. And Dr Tom Tibbits has become director of product marketing in a move from his previous role at QuantaSol as product engineering director. www.quantasol.com BTU International receives $16 million order for in-line diffusion equipment BTU International, Inc., received a $16 million order for solar cell processing equipment. Revenue recognition for this order is projected to start in the fourth quarter of 2010 and continue through the first half of 2011. “Our vision—shared by certain key customers—of using in-line thermal processing for the diffusion step in the production of silicon solar cells has now been validated after several years of development,” said Paul van der Wansem, chairman and CEO of BTU International. “In particular, BTU’s knowhow in precision temperature uniformity and atmosphere control for high-volume processing has been a major enabler to achieving the process and cost goals set by our customer. In-line diffusion can significantly reduce the cost per watt while delivering equivalent cell efficiency compared to traditional batch equipment.” www.btu.com Petra Solar inks supplier agreement with Flextronics to facilitate expansion into global market Electronics manufacturing services provider Flextronics will build Petra Solar’s SunWave™ smart energy modules for deployment around the world. The partnership will enhance Petra Solar’s ability to supply its SunWave pole-mounted solar energy systems to international

customers, giving the company the flexibility and scalability to quickly meet the growing demands for its SunWave product and expand into new global markets. This is in keeping with its commitment to create jobs local to its customers, through the manufacturing services provided by Flextronics. www.petrasolar.com, www.flextronics.com Atlas® receives SRCC solar thermal accreditation Atlas Material Testing Technology has received accreditation for the solar collector testing program at its Arizona test facility, DSET Laboratories, by the Solar Rating and Certification Corporation (SRCC).

Atlas successfully passed an onsite audit to SRCC Standard 100 “Test Methods and Minimum Standards for Certifying Solar Collectors”. SRCC Standard 100, along with ISO 9806-1, 2 and 3 standards“Test Methods for Solar Collectors” has been added to the current ISO 17025 accreditation scope. The solar thermal industry has experienced a significant backlog in certification testing due to the lack of SRCC certified testing laboratories and an increase in solar thermal business globally. Atlas made the decision to invest resources to fill this need, re-entering the solar thermal testing market where it once played a major role during the last global solar initiative. www.solardurability.com GT Solar commences installation of new systems at GCL-Solar’s new wafer manufacturing facility GT Solar International, Inc., has begun installation of its new DSS450HP™ crystalline growth systems at GCL’s new wafer manufacturing facility. The new high performance crystalline growth systems are part of a large GCL purchase agreement reflected in the company’s FY2010 year-ending backlog. “GCL is a significantly important customer for us as we are working with both their polysilicon production and PV manufacturing businesses,” said Tom Gutierrez, president and chief executive officer of GT Solar.

“We are pleased that GCL has selected our new high performance DSS450HP crystalline growth system for their new wafer production line. We have put together an aggressive installation schedule

4 – Global Solar Technology – July/August 2010

and have allocated the necessary resources to meet GCL’s timeline for bringing all the units on line demonstrating that we have the experience and depth of resources capable of handling a project of this magnitude and in meeting GCL’s installation timeframe.” www.gtsolar.com Nordson ASYMTEK white paper on conformal coating for solar inverters now available Nordson ASYMTEK has developed new methods of selective conformal coating and process control that can be applied to protect the electronics in solar inverters from harsh environmental factors. Selective coating results in improved reliability and longer inverter life for photovoltaic systems. An explanation of new coating technologies and how they can be applied to the solar inverter manufacturing process is detailed in the white paper, Conformal Coating Improves the Reliability and Life of Solar Inverters. The paper can be accessed at the Nordson ASYMTEK website using this shortened URL: http:// bit.ly/cC7t1b. www.nordsonasymtek.com Suniva increases manufacturing capacity to 170 megawatts Suniva, Inc., has expanded its manufacturing capacity to 170 MW from 96 MW by adding a third cell line at its metro-Atlanta plant. The new solar cell manufacturing line is now in production and will help the company meet continually increasing worldwide demand for its product. Suniva has also expanded its workforce recently, creating more clean energy jobs in the U.S. Suniva completed its first 32 MW manufacturing line in November 2008 and simultaneously announced an additional 64 MW line that was completed in 2009. www.suniva.com New photovoltaic engineering & management association formation meeting a success On Thursday, June 10, 30 engineers and photovoltaic manufacturing professionals met at Flextronics Inc.’s campus in Milpitas, California, to discuss the formation of a new professional association to advance the photovoltaic engineering and related manufacturing professions.

Such an association would address

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Industry news

research, education, industry standards, and training. The meeting began with a welcome by Dr. Dongkai Shangguan, vice president of Flextronics, who discussed the solar industry in general and the need to lower the cost per watt as an industry imperative. Matt Holzmann, president of Christopher Associates, then presented an overview of why an association would be beneficial to the industry and the participants. He placed strong emphasis on a member driven model dedicated to engineering, management, and other related professional activities. There was widespread agreement that such an association would have significant benefits both to participants and the industry at large.

Afterwards, Holzmann stated “This was a great first step. We must now focus on defining the scope and activities of the organization. Member involvement is critical to achieving success.” Committees are now being formed to execute the necessary key activities to establish a legal entity and its functions. Contact Matthew Holzmann (matt.holzmann@ christopherweb.com), Jasbir Bath (Jasbir@ christopherweb.com) or Dennis Willie (dennis.willie@flextronics.com) for additional information or to get involved.

The committee invites all photovoltaic industry professionals to participate in this endeavor.

KYOCERA commences U.S. manufacturing of solar modules Kyocera has begun manufacturing solar modules in San Diego, Calif., to serve the U.S. market’s growing demand for clean, sustainable solar electric generating systems. The U.S. module production line will support a new milestone for Kyocera’s solar energy business—global production volume 1 gigawatt of solar cells per year by March 2013. The new solar manufacturing line has an initial production target of 30 megawatts per year. It leverages Kyocera’s world-class U.S. manufacturing capabilities to produce the company’s most powerful and efficient solar power products. Initial production includes solar modules ranging from 210 watts to the company’s latest flagship 235-watt modules. www.kyocerasolar.com JA Solar acquires Shanghai Jinglong Solar Technology Co., Ltd. JA Solar Holdings Co., Ltd., has entered into an agreement to acquire 100 percent of the shares of Shanghai Jinglong Solar Technology Co., Ltd. from

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Ningjin Jinglong PV Investment Co., Ltd., a company controlled by JA Solar’s chairman, Mr. Baofang Jin. Located in the Minhang Export Processing Zone within the Fengxian district of Shanghai, Shanghai Jinglong Solar Technology Co., Ltd. owns the land, building and facility currently being leased by JA Solar for its module production operation in Fengxian, Shanghai. Through the acquisition, JA Solar would acquire approximately 206,590 square meters of land, 58,706 square meters of buildings and related facilities. Under the terms of the agreement, JA Solar will acquire Shanghai Jinglong Solar Technology Co., Ltd. for a cash consideration of RMB 198.96 million (US $29.3 million), representing the fair value of the company based on an independent third party valuation. www.jasolar.com Bloo Solar selects CVD Equipment Corporation to design and manufacture equipment for TCO coatings Bloo Solar selected CVD Equipment Corporation (CVD) to develop and manufacture the equipment for its unique 3rd generation three dimensional architecture, thin film, solar module.

Bloo Solar, has started its Solar Brush wafer development production run, which it plans to bring to market with initial commercial modules in 2012. Bloo Solar’s Solar Brush is a 3rd generation technology that has many fundamental advantages over existing PV technologies that rely on traditional planar solar cells. The three dimensional single junction architecture provides more surface area, superior light trapping and minimum recombination to provide higher efficiency and a total power output up to 1.5 to 3 times higher than current technologies. www.bloosolar.com Odersun opens first factory for design solar modules Innovation goes into production as Odersun inaugurates its second solar factory, SunTwo. At the opening ceremony, Economics Minister of the State of Brandenburg Ralf Christoffers received a new type of solar module as an example for the possibilities of individual solar design. The company had already started ramping-up the production at its SunTwo facility in Fürstenwalde (Spree), Germany, when it achieved the IEC 61646 certification in January this year. Based on Odersun’s proprietary CISCuT-technology both standard as well as customized thinfilm solar modules are produced in volume

at the facility. By now 111 employees of Odersun AG work in four shifts in the fully integrated manufacturing of thin-film solar cells and modules in Fürstenwalde (Spree). At the end of this year the workforce will have increased up to 150 people. Initially the factory has a capacity of about 20 MW, which can be expanded to 30 MW by installing two additional production lines in the factory. www.odersun.de Stion kicks off 100 MW expansion and partnership with TSMC Stion announced a production partnership with TSMC of Taiwan. Stion will commence a 100 MW expansion of its San Jose, Calif., facility following the close of its $70 million Series D financing.

Stion had previously raised $44.6 million in equity financing. Stion’s panels are specifically designed for use in all major applications, including commercial/ government, residential, utility and off-grid. The panels are produced using monolithically integrated circuits and offer a number of advantages over competing products, including high efficiency, a convenient form factor (2 ft. x 5 ft), improved performance in partial shading, and superb aesthetics. As part of the expansion, Stion expects to bring more than 500 direct and indirect jobs to the region in 2010 and 2011. www.stion.com MEMC completes acquisition of Solaicx MEMC Electronic Materials, Inc., completed the acquisition of privately held Solaicx. At closing, MEMC paid the initial merger consideration of $66 million in cash, plus an additional amount in cash of approximately $10 million that is equal to amounts that have recently been invested in Solaicx by its existing security holders.

The acquisition is expected to be accretive to earnings per share in 2011. Solaicx, headquartered in Santa Clara, California, has approximately 80 employees and a large-scale production facility in Portland, Oregon. As a result of the acquisition, MEMC now has proprietary continuous crystal growth manufacturing technology that yields low-cost, high-efficiency monocrystalline silicon wafers for the photovoltaic solar industry. MEMC also has low-cost polysilicon and crystal operations in North America, with support offices around the world that provide customers with industry-leading customer service. www.memc.com, www.solaicx.com Continued on page 37

Global Solar Technology – July/August 2010 – 5

Turning CIGS thin film into actual solar collectors—a critical step

Turning CIGS thin film into actual solar collectors— a critical step Colin Weightman, Comco Inc.

Microabrasive blasting is coming to the forefront as an economical technology that effectively and safely handles these final-step processes for a growing volume of thin-film manufactures. This paper offers an overview of microblasting technology and its integration into automated copper indium gallium (de) selenide (CIGS) thin film photovoltaic (PV) cell production lines.

Keywords: Thin Film, CIGS, Microabrasitve Blasting, Edge Deletion, Selective Layer Removal

Overview of CIGS technology CIGS process (copper indium gallium (di)selenide) is the fastest growing area of thin film PV (photovoltaic) technology today. As is well known, CIGS uses basic semiconductor technology to deposit the various material layers onto a substrate, all designed to catch, absorb and contain solar power and then release it back as useable electrical energy. It is being developed in many forms and on many types of material substrates, from highly flexible to rigid.

While not completely competitive to the more mature technology of silicon (Si) as far as total power output efficiency, the technology is gaining ground because of lower production cost, lower cost per watt efficiency and the flexibility to be used in areas where crystalline panels simply do not offer the design options, such as BIPV (building integrated photovoltaics).

Unlike silicon, the structure of a CIGS cell is more complex. It is even more complex than its thin film siblings, cadmium telluride (CdTe) and amorphous silicon (a-Si). Though CIGS solar cells are not as efficient as crystalline solar

cells, they were substantially lower in cost to produce until the recent drop in the cost of silicon. Despite this unfavorable change in the cost ratio between the two technologies, thin film in all its varieties is making steady gains on Si in some utility farm markets where actual land space is not at a premium. Being a direct bandgap material, CIGS has very strong light absorption qualities that make it very attractive for use in hot, arid geographies where silicon is adversely affected by the climate. Also, unlike Si, CIGS TFPV can be flexible which makes it very attractive for the BIPV market.

This flexibility lies in the fact that the active layer (CIGS) can be deposited in a polycrystalline form directly onto molybdenum coated glass sheets or steel bands or even on metallic ribbon structures. For BIPV, flexibility allows CIGS solar cells to conform to the structural design of the building, rather than forcing the building to adjust to allotting regimented space to flat, silicon panels and racks.

Edge deletion in progress

Figure 1. The unique properties of high-energy abrasive particles make microblasting ideal for CIGS solar cell applications. It cuts without heat or vibration and can selectively remove layers without damaging underlying layers or surfaces.

6 – Global Solar Technology – July/August 2010

Figure 2. Testing nozzles, angles, pressures and distance between the solar cell and the blast can be done manually and the data used to create fixturing for the automated system.

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Turning CIGS thin film into actual solar collectors—a critical step

While CIGS films can be manufactured by several different methods, including vacuum-based processes, sputtering, co-evaporation and even electroplating, the end result is the same: a receptacle that gathers in sunlight and transforms it into usable energy. While this statement is quite overly simplified, that is the desired end result.

One aspect of final CIGS cell production still must be met to complete the picture-the power must actually get out of the cell. Electrical contact must reach through the deposited layers. This can involve final processing in one or both of two areas: edge deletion and selective layer removal.

Edge deletion and selective layer removal In the edge deletion process, the solar cell manufacturer needs to get down completely to the substrate layer. On a glass panel, for example, all of the layers down to and including a small amount of the glass may need to be removed to ensure that there is no conductivity between the solar layer and the edge of the glass.

This allows the cell to be isolated in its mounting fixture and is governed by the UL requirements.

The layers need to be removed below a certain conductivity range. One of the processes commonly used is laser. The challenge faced with this method, however, lies in the ability to circumscribe the cell and remove all the layers without melting into the glass or other substrate.

As an alternative, microblasting technology allows the user to affect the surface finish and remove all of the layers at the edge away right down to the glass without heat or damage to the glass or other substrate. Once all the layers are removed of course, conductivity drops to zero.

For edge deletion applications the most common abrasive is alumina. This crystalline material quickly cuts through all of the thin film layers, down to the glass substrate. In the normal thin film deposition process the bottom layers are partially melted into the glass creating a transition boundary that must be removed to completely block conductivity.

Microabrasive blasting is able to etch into the glass surface without creating microfractures.

Microabrasive blasting is seen as a common alternative to the use of lasers and grinding wheels. The blasting process can be seen as a middle ground between the other two processes. The process uses

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a non-contact approach that removes material at a consistent rate and is less dependent on the layer composition.

Selective layer removal is generally needed for new multi-layer thin film technology cells such as CIGS. Since these cells have multiple conductive layers, the manufacturer must locally remove the top layers without damaging the molybdenum (Mo) conductive layer coating the glass, metal or other substrate. Once the layers have been removed, a connector can be mounted, allowing the electricity to be harvested.

The challenge in this application is the need to remove a relatively thick layer of CIGS (1.5 to 2.5 microns), without damaging the much thinner layer of Mo behind it (0.3 to 0.4 microns). Through proper selection of the abrasive media and air pressure (PSI) the microabrasive blasting process can be made much more effective on the CIGS layer than the Mo. Consistent abrasive feed is critical in this application to completely remove the CIGS layer without damaging the Mo. These are small and yet highly critical steps in the final cell production process and several methods have been used, with varying success, including lasers, machine cutting tools and grinding.

Microblasting technology overview Microabrasive blasting projects a blast of clean, dry air mixed with highly pure, micron size abrasive media, delivered through a nozzle selected to suit the application. This must be performed in a vacuum activated chamber to remove the dust created by the process.

For most processes, microblasting remains a manual art that is performed by an operator within a clean workstation.

The psi, media mixture and safety measures are automatic; an operator controls the direction of the blast.

To eliminate operator variance, more automated systems are being developed by end users and as custom systems by microabrasive blasting equipment manufacturers.

Microabrasive blasting technology itself is well known in many industries ranging from electronics and machining to medical device finishing and aerospace. Because of its effective use in the semiconductor area, it was a natural choice for many thin film developers, who have a background in semiconductor technology. Since CICS is an advanced version of the same processing as seen in the semiconductor industry, microabrasive blasting is a natural fit for CIGS finishing applications.

Figure 3. A wide variety of abrasive media allows a selection to suit any application from precision cutting to gentle surface finishing.

Figure 4. Nozzles for microblasting are available in a range of materials, sizes and shapes to fit the specific applications. Openings run from .015 in. up to .125 in.

Recent advances in microblasting technology enable the equipment to flow very small abrasives at highly consistent rates. The growth of automated systems that can accurately position both single and multiple abrasive nozzles and nozzles and monitor process variables like media flow rates also offers expanded options for thin film processing.

The unique properties of high-energy abrasive particles make microblasting ideal for CIGS solar cell applications. It cuts without heat or vibration and can selectively remove layers without damaging underlying layers or surfaces. The ability of microabrasive blasting to do this without causing dimensional changes to the surrounding cell layers make it ideal for finishing applications. Propelling a very fine, dry-abrasive powder mixed with clean, compressed air through nozzles with openings as small as 0.018 to 0.060

Global Solar Technology – July/August 2010 – 7

Turning CIGS thin film into actual solar collectors—a critical step

Figure 5. An example of an automated in-line microblasting lathe in action.

inches, the pinpointed abrasive blast can be as tight or as broad as the application requires.

The affect can be altered significantly by changing the pressure or abrasive media.

The two most common abrasive media used in the solar industry are glass bead, which has a gentle affect on a surface and aluminum oxide, which is highly effective at cutting through almost all materials.

Integration into automated CIGS thin film cell production lines As noted above, most applications for microabrasive blasting are still conducted in a manual workstation. However, within solar applications and particularly within thin film area, the microabrasive blasting process is always integrated into an automated production line.

CIGS thin film production is an automated process, very similar to that seen in the semiconductor industry. The development of the PV material runs on an automated line, with the final product handled and indexed through this line.

Because how each CIGS manufacturer sets up a line tends to be highly proprietary, in most cases,

the manufacturer will buy a high-end microabrasive blasting system and then integrate this into their own line.

This can be done easily because there is a protocol in the semiconductor industry, a certain form factor and a specific handling process that is required. The most common scenario is where the CIGS manufacturer has a system integrator either set up the full automated line or, at minimal, integrate the automated microabrasive blasting system into an existing line.

The microabrasive blasting equipment manufacturer acts as a consultant.

Typically, the CIGS manufacturer needs to learn about the microblasting process, and the equipment supplier works with them to make sure the process is smooth and working efficiently. Again, cell finishing tends to be somewhat proprietary, and depending on the actual substrate or any specific technology used, the microabrasive blasting integration set up tends to be slightly different at each installation.

Selecting a microabrasive blasting system that has been carefully engineered to operate in an automated environment

8 – Global Solar Technology – July/August 2010

is critical. But even after installation, some customization is commonly needed for the application.

Depending on the rate of use, throughput, and so forth, options such as different abrasive hose materials may need to be considered. These can range from standard polyurethane to stainless steel.

However using stainless does limit all the lines to fixed positions. The trade off is that stainless lines last 10 times longer than polyurethane.

Other blasting variables such as nozzle location (i.e. the distance from the tip of the nozzle to the surface of the cell) must be determined. As the nozzle is moved away from the part, the spray diameter will increase. The nozzle must be placed so that the media is focused on the exact area that needs to be removed.

Nozzle shape also affects the spray pattern of the nozzle. Microabrasive blasting nozzles are available in many different sizes and shapes, from small round to large rectangular. Rectangular nozzles offer the ability to increase spray width in one direction without increasing the overall blast diameter.

These variables combined with pressure, abrasive flow rate and blast duration, create the proper profile for each type of material removal. Integrating machinery from different vendors to create unique automated systems is something that takes full understanding of each process. But, through the integration of all the various manufacturing operations, the end result is a product that is more cost effective, less operator dependent, and uniform in quality.

The system integrator needs to carefully study the current process, looking for variables that might affect the microabrasive blasting process. Simple tasks are often much more complex than they appear. The skill of the operators must be taken into consideration and duplicated as much as possible with an automated system. Testing nozzles, angles, pressures and distance between the solar cell and the blast can be done manually and the data used to create fixturing for the automated system.

Materials and techniques Glass bead or aluminum oxide are the abrasive media typically used for these two applications. They create very different results in the actual material removal process, so it depends on what is being removed and where, and if only selective layers are being removed, or all of the layers are.

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Turning CIGS thin film into actual solar collectors—a critical step

Conclusion Microabrasive blasting is coming to the forefront as an economical technology that effectively and safely handles these final-step processes for a growing volume of thin-film manufactures.

Looking at a basic analysis of cost saving in overall usable end product vs. other removal technologies, microabrasive blasting offers a higher level of precision than most mechanical methods for performing these processes and is typically less expensive than lasers. Microblasting offers reliable and consistent results without environmental issues associated with chemical processes.

The level of control afforded using the microabrasive blasting process ensures more quality connections without damage to the infrastructure of CIGS solar cells, helping to enhance the growth in product reliability for CIGS thin film in the growing solar market.

Figure 6. A wide range of microblasting formats are available for integration into customized automation production lines, depending on the end result desired.

If trying to cut through a layer to isolate it, aluminum oxide has fast cutting properties. If the objective is to remove a lot of the thin film layers down to the conductive Mo layer, glass bead is more effective. Because the Mo layer has a certain amount of elasticity it’s going to take the energy of the particle and absorb it and then give it back off again. It allows the glass beads to bounce, unlike some of the harder thin film layers, which crack or fracture when hit. In this case the goal is not necessarily trying to clean-cut off the material as much as trying to break it

up and then the follow up with a vacuum process that will lift away the debris after shattering the layers above the Mo. Using a high energy, energy sharp, harsh abrasive like aluminum oxide will cut away all layers, but it will also cut into the Mo layer.

Depending on the substrate—glass, metal, flexible ribbons or rolls—all would still be applicable for this glass bead type of process. But certainly, depending on the exact substrate the manufacturer would need to experiment with the abrasive media to determine the best selection.

Colin Weightman is the director of technology at Comco Inc. During his tenure at Comco, he designed a new line of nozzles for abrasive blasting that provide a tighter focus and longer life than conventional nozzles. He also developed Comco’s Applications Lab which provides sample parts testing to prove the microblasting process. Following a stint as technical sales manager Mr. Weightman has returned to a more research-based role. He works directly with clients to find ways in which microabrasive blasting can solve problems faced in the manufacture of new technologies such as those found in the emerging solar industry.

Vacuum Solutions for the Solar Industry Busch designs and builds vacuum systems that Vacuum Systems are individually by suited to meet the Busch application needs and requirements of our customers.

Skilled engineers work together, under the direction of a project manager, to design the plans for the system, which qualified personnel then build at our facility. Expect the best when you specify Busch.

1-800-USA-PUMP www.buschusa.com

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Global Solar Technology – July/August 2010 – 9

The effect of the firing process on the energy conversion efficiency of solar cells

The effect of the firing process on the energy conversion efficiency of solar cells

Ben Sun, Heraeus Materials Technology Shanghai LTD, and Crystal Han, Topsola, Shanghai Over the last few years, solar cell manufacturers have strived to improve energy conversion efficiency at a lower cost.

Optimizing the metal electrodes firing process in furnaces is a common way to achieve this goal. This was overlooked in the past. Most of the time, such thermal process work was done mainly by experienced engineers without much indepth engineering study and development. This article will introduce a method of profiling and optimizing furnace setpoints in the crystalline silicon solar cell manufacturing process using SunKIC in order to achieve optimal results for a stable and high solar energy conversion at Topsola’s factory in Suzhou, China.

Keywords: Thermal Profiling, Furnace Setpoins, Crystalling Silicon Solar Cells

Principle of experiment After selecting the initial furnace setpoints, the actual profile on the surface of the crystalline silicon solar cell was measured and recorded using KIC’s SunKIC profiler.

By methodically selecting new furnace setpoints and analyzing the resulting profile characteristics and their respective energy conversion efficiency, the process window and optimal profile can be determined using the profiler software. The energy conversion efficiency of each cell will be calculated.

Material and equipment list Silicon solar cell: 125 x 125 mm Aluminum paste: All sample use the same type of aluminum paste Silver paste: Front side Heraeus CL80-9235HL; Rear side Heraeus SOL230S Printer: ASYS Furnace: Despatch CF7210 Profiler: KIC SunKIC

No

Avg. conversion efficiency %

1 2

Experiment A reference or base profile was selected to fire 30 pieces of solar cells. The average efficiencies were then computed. The final heating zone of the furnace was varied manually to develop different profiles. For each unique profile, 30 cells were fired. Table 1 shows the results of six different profiles. The seventh profile was determined by KIC’s Spectrum optimization software. Figure 1 depicts the average cell efficiency for each set of 30 cells fired at the listed furnace setpoints.

The actual peak measured temperature also is displayed.

Analysis and discussion The box chart shown in Figure 2 depicts the results of the average energy conversion efficiency of solar cells fired at different profiles. We can see that result using profile 3, 4, 5 and 7 had a higher efficiency and less variation. From Table 1, we can see that the average peak temperatures were 842˚-865˚C. This is the peak temperature process window for firing such paste.

Furnace Setting ˚

Actual peak temp ˚C

1

2

3

4

5

6

17.1276

400

500

610

700

800

895

820

17.1875

400

500

610

700

800

905

829

3

17.2766

400

500

610

700

800

920

842

4

17.2787

400

500

610

700

800

930

851

5

17.2778

400

500

610

700

800

945

865

6

17.1283

400

500

610

700

800

955

871

7*

17.2753

400

500

610

700

844

923

851

* Profile by KIC optimization software Table 1. Average energy conversion efficiency of various profiles.

10 – Global Solar Technology – July/August 2010

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The effect of the firing process on the energy conversion efficiency of solar cells

The optimized profile 7 in Figure 3 has a 0.15 percent higher efficiency than the initial profiles. It also has better stability as compared to profiles 3, 4, 5 and 6. This reduces the number of lower efficiency cell produced, hence improving the productivity and cost at Topsola’s factory in Suzhou China.

Conclusion In summary, the accurate measurement of the cell profiles and optimization of the furnace’s temperature settings during production play an important role in process control. Frequent tracking on the furnace’s temperature, collecting and analyzing measurement data can help optimize the firing process and find a suitable process window. The end result is the production of higher efficiency cells, stable production quality and reduced production cost.

Figure 1. Spectrum optimizing software interface.

Figure 2. Average energy conversion efficiency for various profiles.

Figure 3. Distribution chart of energy conversion efficiency for various profiles.

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“Accurate measurement of cell profiles and optimization of furnace temperature settings during production play an important role in process control.”

Global Solar Technology – July/August 2010 – 11

Novel thin-film crystalline Si solar cell approaches

Novel thin-film crystalline Si solar cell approaches Mieke Van Bavel, Ivan Gordon, and Valérie Depauw, Researcher, imec, Leuven, Belgium

The most pressing challenge in Si solar cell technology is to make solar cells cheaper. One route to achieve this goal is by using less Si, which today is being done by using ever thinner Si wafers for the solar modules. On a longer term, the Si consumption can be further reduced by using crystalline-Si thin films as the active solar cell material and low-cost substrates as a carrier. In this paper, we propose two innovative thinfilm monocrystalline-Si solar cell concepts and discuss their potential. A first approach relies on the creation of a thin crystalline-Si seed layer, followed by epitaxial thickening of the seed layer. Solar cells processed from the resulting monocrystalline-Si layers reach efficiencies of up to 7.5% and certainly leave room for improvement. A second approach focuses on avoiding the expensive epitaxial deposition step, by directly transferring a thin absorber layer of monocrystallineSi to a foreign low-cost substrate such as glass. This transfer is enabled by the reorganization of macroporous Si at high temperatures. Although the efficiencies are as yet relatively low, the real breakthrough is in providing a material with good quality without resorting to epitaxy.

Keywords: Thin Film, Seed Layer, Thin Absorber Layer

Towards thin-film Si solar cells: an introduction The manufacturing of photovoltaic (PV) systems is one of the fastest growing energy-related sectors in the world. For the past 10 years, the number of solar cells that is being produced yearly (in terms of Watts produced by these solar cells under a standardized spectrum) has been growing consistently. In 2008, this trend continued with a total production level near 8 GWp, representing a total turn-over of the sector near 30 billion euro.

For years, the PV industry has been dominated by crystalline Si solar cells, with a market share of about 85% of the total world solar cell production in 2008.

Crystalline Si is still the only material that enables solar cell installations to function more than 20 years. Yet, if we want PV energy generation to be a relevant part of the total electrical energy generation, the cost of such a PV system, presently around 3.5-5 euro/watt, must be reduced by at least a factor of four. Cutting down the costs is to be done by economies of scale (larger plants), but it also requires technological breakthroughs to reduce the cost of materials to manufacture cells and modules, to reduce the energy input to realize these components and to increase

Figure 1. Schematic drawing of the simple solar cell test structure used in this work.

12 – Global Solar Technology – July/August 2010

the energy conversion efficiency.

When analyzing the costs of present Si PV modules, it turns out that almost half of the price is currently due to the expensive electronic-grade Si in the solar cell. Hence, the main road that is being followed today is to reduce the thickness of the Si wafers that are used to produce the solar cells. Whereas in 2004, the standard wafer thickness in industry was still near 300 µm, it was 200 µm in 2008, and 180 µm is now becoming generally used. The Si content can be even further reduced to levels far below 1 g/Wp by going to thinfilm crystalline Si approaches where a thin film of Si (less than 20 µm) is deposited on a low-cost substrate. Promising results have been obtained with epitaxial solar cell concepts, where a low-cost highly doped crystalline Si substrate is being used on top of which an epitaxial Si layer is deposited.

With such a technique, thin-film solar cells that compete with Si-wafer based cells can be provided.

In this article, we present alternative thin-film Si solar cell approaches. They have in common the use of a low-cost foreign substrate and hence a further cost reduction potential. In a first approach, the technology is based on the creation of a thin crystalline-Si seed layer followed by epitaxial thickening of this seed layer. A second approach allows the development of epitaxy-free thin-film solar cells that allow an even larger price reduction.

Innovative seed layer approach One way to create a crystalline-Si thin film on a non-Si substrate for solar cell applications is by using a seed layer approach: a thin crystalline-Si seed layer is first created, followed by epitaxial thickening of the layer. This is preferred over direct deposition of Si on the nonSi substrate, since this would result in amorphous or small-grained material.

With the seed layer approach, promising thin-film polycrystalline solar cells with relatively large grain sizes (between 1 µm and 1 mm) have already been fabricated.

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Novel thin-film crystalline Si solar cell approaches

Such cells could be of interest, since they combine the low-cost potential of a thin-film technology (like amorphous Si) with the material quality potential of a crystalline material. At imec, we made polycrystalline seed layers by using aluminum-induced crystallization (AIC) of amorphous Si and thermal chemical vapor deposition (CVD, at temperatures above 1000˚C) for the epitaxial thickening. Both alumina and glass-ceramic materials were used as a substrate. However, the problem with these polycrystalline layers is the high density of electrically active intragrain defects. These defects today limit the performance of the cells to 8%. Improving these cells requires better AIC seed layer quality.

The use of monocrystalline-Si seed layers could be beneficial, since it would enable simpler device processes, a higher process yield and a single-crystal-like efficiency because of an intrinsic higher material quality. To explore this idea, we have made 10 µm-thick monocrystallineSi layers on transparent glass-ceramic substrates1. This was done by using monocrystalline-silicon seed layers on glass-ceramic substrates made by Corning.

These seed layers are made by transferring 300 nm thin (001)-oriented Si single-crystal layers to a glass-ceramic substrate using Corning’s proprietary process that is based on anodic bonding and implant-induced separation2. A barrier layer, formed between the glass-ceramic substrate and the Si layer, prevents the Si layer from being contaminated by the glass-ceramic components. Subsequently, epitaxial thickening of the seed layers was realized in an atmospheric-pressure chemical vapor deposition (APCVD) system.

From a crystallographic point of view, the monocrystalline layers have a much better quality than their polycrystalline counterparts obtained with the AIC approach in the same APCVD systems.

These layers typically show an intragrain defect density of around 108-109 cm-2. The monocrystalline layers have overall defect densities as low as 105 cm-2.

From these epitaxial layers, simple solar cell structures were made which did not integrate any light trapping features. Si solar cells on glass-ceramic reached efficiencies up to 7.5%. For the short circuit current Jsc, which is due to the generation and collection of the light-generated carriers, a value of 23.4 mA/cm2 is reported. The open-circuit voltage Voc, which reflects the amount of recombination in the device, is 514 mV. However, efficiencies above 9% should

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be realizable by using a more advanced contacting structure. In addition, we believe that the efficiency potential of these single-crystal Si thin films on glass-ceramics can compete with wafer-based Si solar cells.

But this will require an optimized minority carrier diffusion length and an integrated efficient light-trapping scheme.

Epitaxy-free layer-transfer approach The use of thin, high-quality layers of Si as the active solar cell material on low-cost carriers is an effective way to decrease the cost of photovoltaic electricity. High cell efficiencies have been demonstrated by layer-transfer processes, where thin layers of epitaxial Si are transferred to cheaper substrates3. Unfortunately, epitaxy is a very expensive processing step that seriously limits the intended cost reduction. Finding a way to by-pass epitaxy and still make highquality thin films of Si would represent a real breakthrough.

At imec, we have developed an innovative, cost-effective process that meets this expectation: we produced monocrystalline µm-thick films by annealing of macroporous Si and demonstrated the potential of this concept for large-area PV applications4,5. In fact, the technique is taken from the field of Si-onnothing structures: it was found that upon annealing of specific arrays of macroporous

Figure 2. Transmission electron microscopy picture of the mono-Si layer on glass-ceramic after epitaxial thickening (cross-section).

Si at high temperatures, the macropores reorganise into one single void and leave a thin overlayer on top. The overlayer was reported to be monocrystalline and defectfree, suitable for MOSFET applications6.

Its employment in PV applications is however not obvious: firstly, much larger areas (cm scale) have to be produced, and, secondly, the film has to be detached and bonded to a foreign substrate.

By using a 4-step approach, we successfully tuned this process to PV applications. In a first step, a very regular array of pores is etched in the Si wafer. To prepare the macroporous structure, we use deep-UV lithography and plasma etching, allowing a perfect control of pore ordering and size. In a second step, the wafers are annealed at 1150˚C in an argon

Figure 3. Epitaxy-free thin-film Si solar cells (1 cm2) on glass. The thin film was obtained by reorganization of plasma-etched macropores in Si.

Global Solar Technology – July/August 2010 – 13

Novel thin-film crystalline Si solar cell approaches

such as achieving a good passivation of the rear-side and incorporating specific lighttrapping schemes will allow a significant increase of the cells performance.

Acknowledgements The authors thank Corning Inc. for providing the seed layers on glass-ceramics used in this work.

Figure 4. Schematic cross-section of two simple epitaxy-free thin-film Si solar cells on glass with heterojunction emitter.

or a hydrogen atmosphere, resulting in a 1 µm-thick film, as large as 5 x 5 cm2.

In a third step, the film, still attached to its parent wafer, is bonded to a thick substrate for handling. We have used anodic bonding to glass, because this bond is direct, permanent and resistant to different chemicals and vacuum as well as heating. Besides, it is compatible with other materials that may be needed for a solar-cell process. After bonding, the thin film attached to glass can be easily pulled apart from its parent Si wafer and is ready for solar-cell processing. The parent wafer can be reused to provide new films. In a fourth and final step, a specific solar cell process is applied using temperatures not higher than 250˚C. The 1 x 1 cm2 solar cells have an amorphous Si/crystalline Si heterojunction emitter, with a full aluminum rear contact.

With this recipe, we made a first proof-of-concept solar cell with an energy conversion efficiency of 2.6%. This result demonstrates the feasibility of the technique for making solar cells without resorting to epitaxy. The experiments also revealed some necessary precautions for material preparation, handling and solar-cell processing. E.g., as long as the film is attached to its parent Si wafer, the film requires to be protected from any electrostatic force, abrupt gas flows and vacuum pumping, in order to avoid early and undesired lift-off. Another necessary precaution is a perfect surface clean before annealing in order to minimize surface and structural defects during argon anneal.

At this stage, the cell performance is rather low but leaves room for optimization. The low open circuit voltage Voc of 341 mV can be explained by the absence of rear-surface passivation and the high material resistivity. In addition, the short-circuit current Jsc, being 14 mA/ cm2, is limited by the very thin absorber layer and by the absence in the cell design of schemes to absorb and trap more light in the material. And finally, the low fill factor of the cell is most likely limited by

the presence of holes in the film, formed during transfer. Hence, optimization of the cell implies an increased film thickness (2-3 µm), improved bonding (to avoid formation of holes), passivation of the rear-side and the addition of light-trapping schemes and surface texturing. Also, deep-UV lithography, used to prepare the macroporous structure, is a rather expensive technique and should eventually be replaced by a low-cost pore-patterning technique, like nanoimprint lithography.

With these improvements, we believe that the epifree cells can reach comparable conversion efficiencies as their epi-based counterparts, without the cost-related bottleneck that epitaxy represents.

Conclusion In an effort to bring down the Si content in solar cells, we have presented two novel thin-film crystalline Si solar cell concepts that make use of cheap non-Si substrates.

A first approach is based on the creation of a thin crystalline-Si seed layer followed by epitaxial thickening of this seed layer. This has resulted in µm-thick monocrystalline-Si solar cells on glass-ceramic substrates with efficiencies up to 7.5%. By implementing a more advanced contacting structure, by optimizing the minority carrier diffusion length and by integrating an efficient light trapping scheme, efficiencies comparable to wafer-based Si solar cells should become feasible. Although this is a very promising technique for making good-quality thin-film Si solar cells, the expensive epitaxial step could limit its cost-reduction potential. In a second approach, we propose to by-pass epitaxy by directly transferring a thin absorber layer of high-quality monocrystalline Si to a foreign low-cost substrate. The transfer is enabled by the reorganization of macroporous Si at high temperatures.

Proof-of-concept solar cells have shown the feasibility of the technique to make good-quality solar cells without falling back on epitaxy. Conversion efficiencies are so far limited to 2.6%, but improvements

14 – Global Solar Technology – July/August 2010

References 1. I. Gordon, S. Vallon, A. Mayolet, G. Beaucarne, and J. Poortmans, ‘Thinfilm monocrystalline-silicon solar cells on transparent high-temperature glass-ceramic substrates’, Solar Energy Materials and Solar Cells 94 (2010) 381-385.

2. R.G. Manley, G.L. Fenger, P.M. Meller, K.D. Hirschman, C.A. Kosik Williams,D.F. Dawson-Elli, J.G. Couillard, J.S. Cites, ‘Development of integrated electronics on siliconon-glass (SiOG) substrate’, ECS Transactions 16 (9) (2008) 371–380.

3. M. Reuter et al., ‘50 µm thin solar cells with 17.0% efficiency’, Sol. Energy Mater. Sol. Cells 93 (2009) 704-706.

4. V. Depauw, I. Gordon, G. Beaucarne, J. Poortmans, R. Mertens and J.-P. Celis, ‘Proof of concept of an epitaxyfree layer-transfer process for silicon solar cells based on the reorganisation of macropores upon annealing’, Materials Science and Engineering, B 159-160 (2009) 286-290.

5. V. Depauw, I. Gordon, G. Beaucarne, J. Poortmans, R. Mertens and J.-P. Celis, ‘Innovative lift-off solar cell made of monocrystalline-silicon thin film by annealing of ordered macropores’, Phys. Status Solidi C 6, No. 7 (2009) 1750-1753.

6. T. Sato, et al., ‘Fabrication of Siliconon-nothing structure by sustrate engineering using the empty-space-insilicon formation technique’, Jpn. J. Appl. Phys. 43 (2004) 12-18.

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Title

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Global Solar Technology – July/August 2010 – 15

Performance chemicals in cell manufacturing

Performance chemicals in cell manufacturing Johan Hoogboom, Suzanne Kuiper, Paul Thomassen, Mallinckrodt Baker BV

Whether it’s monocrystalline, multicrystalline, batch or inline, every solar cell manufacturing process contains several key steps that rely on wet chemical modification. Until a few years ago, the chemistry involved was no more than simple acidic or alkaline dips using commodity chemicals. With cell efficiencies continuously on the rise and new cell concepts slowly being introduced into high volume manufacturing, attaining even an incremental increase in conversion efficiency or process yield can make a huge difference in company revenue.

Instead of using commodity chemicals, realizing increases in cell efficiency or production yield today requires the use of high-performance chemicals, which are capable of optimizing multiple process steps, such as tuning emitters. As a result, cell manufacturers increasingly turn to performance chemicals to adjust their standard processes.

In standard cell manufacturing, most wet chemistry is used in wafer sawing/ cleaning, texturing, emitter deposition, phosphosilicate glass (PSG) removal, emitter optimization, electrode formation and edge isolation. For emerging higherefficiency concepts, selective etching and increasing surface passivation are key.

Example—emitter optimization In a p-type silicon solar cell, charge separation is enabled by the emitter, which is formed by the thermal diffusion of phosphorous into a boron-doped silicon wafer.

This leaves a highly doped top layer, which is a major source of charge recombination.

This top layer is comprised of two zones.

The top zone consists of PSG leftover from the emitter source material (phosphoric acid or POCl3), which is partially dissolved in a standard manufacturing process by a simple HF dip. The second zone is the so-called dead layer, which consists of non-electrically active phosphorous. This layer cannot be substantially removed by a simple HF dip. Removing the PSG layer and etching part of the dead layer reduces

the amount of surface recombination of charge carriers, substantially increasing short-circuit current and thereby the efficiency of the cell.

After PSG removal by an HF dip, substantial amounts of PSG remain on the surface. Traditionally, cleans like RCA clean are used for additional surface cleaning. Unfortunately, these cleans involve a two-step process (excluding rinsing) at very high temperatures, which makes this industrially unattractive. In 2006, Mallinckrodt Baker and the Energy research Centre of the Netherlands (ECN) developed a one-step alternative, which was presented as the ECN-Clean process, containing Mallinckrodt Baker’s J.T.Baker® PV-160 solar cell surface modifier.

Laboratory experiments have shown that improvements in efficiency resulting from the ECN-Clean step were due to an increase in voltage and current (both by almost 1%), while the loss in fill factor was small. This increase was found to be irrespective of wafer position in the ingot.

In contrast, applying a standard RCA clean resulted in a dramatic loss of fill factor of several percent, drastically reducing final cell efficiency.

Opportunities Texturing and emitter optimization show that the use of performance chemistry can increase both cell efficiency and production yield, while simultaneously lowering cost of ownership. There are, however, many more opportunities for the applica-

16 – Global Solar Technology – July/August 2010

tion of performance chemistry in solar cell manufacturing. In standard cell production, wafer sawing and cleaning will be one of the future focal points for wet performance chemical applications. Removal of organics and silicon carbide from the sawing slurry, as well as dissolution of ingot glue is currently done in multi-step processes, which have reached the limits of their performance. Consolidation into fewer steps, and improving on performance will ensure increased ease-of-use for wafer producers and cell manufacturers alike. Additionally, the introduction of new pastes, capable of contacting ever higher ohmic emitters, and the use of new printing techniques such as stencil printing will also continue to increase cell efficiencies.

Reducing surface recombination will become crucial, as normal production processes use ever thinner wafers, and with high-efficiency cell concepts slowly coming to market. Increasing surface passivation with wet chemistry, or ensuring that the surface is clean and homogeneous prior to deposition of passivation layers, will be key for attaining ever higher cell efficiencies.

As interfaces become more and more important in increasing cell efficiency, solutions that can control surface properties and homogeneity will surely be incorporated into industrial production schemes. This entails that the development and application of cuttingedge performance chemistries will surely be a focal point for technologically innovative chemical companies for some time to come.

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Millinckrodt Baker interview

Mallinckrodt Baker interview At Intersolar, I got an opportunity to talk to John Bubel, director of marketing for microelectronics at Mallinckrodt Baker, and Theo Trommelen, business manager for microelectronics Europe. Mallinckrodt Baker produces the J.T.Baker® brand of high purity chemicals for solar cell surface prep and cleaning.

Q: How would you describe your solar business?

A:We produce formulated performance chemicals to improve cell and manufacturing efficiency. We have many years of experience in the semiconductor industry and we are applying this to the photovoltaic systems. It is a materials rich but very price sensitive market and we are in a good position to meet the industry’s needs.

Q: What types of chemical systems do you offer?

A: We have a particular interest in water-based systems to modify surfaces—for example after the diffusion process. Surface residues in particular can really affect efficiency. As wafers get thinner we need to do everything possible to reduce recombination and other loss mechanisms.

Q: How do you support customers worldwide?

A: Our solar research lab is in Deventer, The Netherlands, and we have other application labs in the U.S. and Korea with one on the way in Taiwan.

Q: Where do you see the business developing?

A: We’re developing innovative process solutions for the solar energy industry rather than providing products. We feel this is the best way forward to improve performance and yields.

Q: On May 26 Covidien announced an agreement to sell Mallinckrodt Baker to New Mountain Capital.

The deal is expected to close in the fall. How will that affect you?

A: Operations are expected to continue as usual with no impact or process changes anticipated for our customers. The transaction will create an exciting opportunity for us to pursue new growth initiatives in technology driven markets, including solar.

joint World Conference of:

—Alan Rae

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Global Solar Technology – July/August 2010 – 17

Innovation from wafer handling to panel installation

Innovation from wafer handling to panel installation Alan Rae

Bosch Rexroth has a unique integrated process approach to the PV market. Vertical integration means that a solution from the aluminum extrusions up and from the software down is available to companies looking to improve their materials handling at the wafer level and the module level. Their partnership with Bosch Solar has also led to novel product offerings at the module level. Image courtesy Intersolar Europe Danielle Collins (application engineering manager) of Bosch Rexroth showed me round the Intersolar booth which showcased many of their products. There was a lot to see, and so I have highlighted two areas of particular interest to readers looking to lower costs, improve yields and improve flexibility.

The first item covers their innovative slide-in panel mounting system, the second covers automated handling of wafers.

18 – Global Solar Technology – July/August 2010

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Innovation from wafer handling to panel installation

Slide-in system for installing frameless thin-film solar modules Bosch Rexroth showcased an innovative slide-in system for installing frameless thinfilm solar modules made by Bosch Solar Energy AG. The combination of support and photovoltaic module enables solar modules to be installed twice as fast as they would with conventional mounting systems.

Speed is assured due to the reliable, easy-to-use slide-in technology, which relies on tracks instead of the usual clamps. The photovoltaic modules are simply inserted into the guide pieces and fastened instantly.

The system cuts installation time in half to 15 seconds per module, meaning around twice as many modules can be installed using Rexroth slide-in technology as they would using a conventional, four-point clamping system in the same amount of time. As installation brackets and clamps are no longer required, material costs are also reduced by about 40 percent.

“Together with Bosch Solar Energy’s micromorph thin-film solar modules, we are able to provide a competitive system consisting of a substructure and a photovoltaic module which combines the lowest system costs, the lowest number of individual components and the shortest installation time,” explains Jörg Walther, head of assembly technology in the linear motion and assembly technologies business area at Bosch Rexroth.

The system is built on a base frame that features variable table lengths, bracket spacing and insert depth. Together with the slide-in track, the frame forms a complete unit that securely encloses solar modules on a permanent basis. The module structure is also perfectly matched to the system.

With their hardened front glass, Bosch Solar Energy’s micromorph thin-film solar modules can withstand mechanical loads up to 2,400 pascals in this mounting system.

This corresponds to 350 kilograms of weight acting on the module.

Bosch Rexroth and Bosch Solar Energy are now exploring a further development of this unique integrated system. In the near future, it should also be available for framed modules and, consequently, for crystalline applications, smaller rooftop systems and special uses, such as systems in coastal areas.

The system has already been used to install around 75,000 Bosch modules.

Wafer handling systems Bosch Rexroth develops custom automation solutions in cooperation with the manufacturers of production systems for photovoltaic modules. Rapid growth leads to a process of continuous change, which makes the planning of production facilities more difficult. To keep costs down, it is

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Bosch Rexroth installation at Heckert Solar, Chemnitz Germany, with the TSsolar Conveyor, one of the products on display at the company’s Intersolar booth.

necessary to automate processes as much as possible, which in turn carries its own risks when technical development is taken into account. Systems can rarely be used for many years without upgrade or innovation.

The transport and handling systems employed must therefore be flexible enough that work stations can be added or replaced without compromising the fast and delicate handling of the cells and panels.

In the semiconductor and the solar industry, tools need a reliable mechanism to transport wafers into, within and out of chambers for various processes like deposition or etching. Rexroth’s Linear Motion System has a proven track record as a high-precision drive solution in PECVD (plasma enhanced chemical vapor deposition) applications under vacuum conditions on photovoltaic cell production lines. A coil mounted outside the process chamber drives the carrier with a magnet track mounted on it. Hall sensors ensure excellent repeatability. The solution is highly modular and scalable: by simply adding more coils, the carriers can be driven over longer distances. The Rexroth NYCe 4000 integrated drive & control platform used in the Linear Motion System can handle a wide power range. The carriers are driven independently and can have different motion profiles, providing a solution which can handle complex motion operations.

The linear drive system delivers reliable operation under any of the

process conditions which are needed to manufacture displays, optical components, photovoltaic cells and semiconductors including vacuum, inert gas or temperatures up to 110°C. The innovative technology greatly simplifies the design of highly complex production lines and eliminates the need for failure-prone seals on motors, mechanical subassemblies and supply lines.

The Rexroth NYCe 4000, which has been optimized for semiconductor and solar applications, controls high-precision positioning and motion profiles which are gentle on the process material. Every node in the distributed network controls up to 10 linear drive coils and communicates via a bus system with the control software which is loaded in a PC. High-end motion control featuring open software architecture provides an extremely flexible automation solution for modules and complex machines, and it offers OEMs excellent know-how protection.

Programming using the flexible C-interface shortens the development cycle. Users have comprehensive motion functionality at their fingertips which enables them to meet demanding speed and precision requirements. Up to 120 digital and analog I/Os are available to connect sensors and handle very complex process steps. The modular system design is ideally suited for large machine engineering projects.

Global Solar Technology – July/August 2010 – 19

The economic manufacturing of semi-transparent BIPV modules Interview

Interview

A new lens on low-cost, green, efficient and reliable CPV coefficient of CPV and the consistent energy production over the whole day really makes a difference to our customers.

Tell us about the units and how they perform?

Our current units are 6 kW panels mounted on ground-based trackers. They have a 25% efficiency, which we are very proud of. That efficiency is not cell efficiency, but is the actual AC system efficiency after the inverter and under full operating temperature. We are still increasing efficiency at about 1% per year and output does not degrade with time.

How do you get the performance and reliability?

The Concentrix booth at Intersolar was mobbed by visitors (a good sign!), so Alan Rae talked offline to Hansjoerg Lerchenmüeller, Concentrix Solar’s CEO, after he had returned to his office in Freiburg, Germany.

How was the show?

Very busy! We actually see that the market in the US is really taking off.

Tell me about the Concentrix CPV units…where is the sweet spot for your product?

Our installations are aimed at the utility size market, typically 10-20 MW, but we can handle up to 100 MW. We do projects that are large enough to be significant, but not too large to be unmanageable. And we are targeting very sunny locations where cost of electricity already today can be as low as $0.13-$0.15 per kWh generated. In these sunny regions the favorable temperature

20 – Global Solar Technology – July/August 2010

The heart of the module is the triple junction solar cell, which delivers efficiencies of up to 40% already today.

The III-V cells have now made major inroads into satellite panel applications because of their output and reliability. In order to get to high module efficiencies we position the solar cell with 25 micron accuracy to make sure that it is exactly in the focus of the Fresnel lens. In our module design, we are using bare dies and this means no potential degradation of encapsulation materials. Then we mount the die to a copper heat sink which spreads the heat and allows a cell temperature of no more than 90˚C, allowing us to operate even in hot arid areas just with passive cooling, so no cooling water required. In fact we believe this is the perfect system for high desert locations.

Any particular challenges?

It was quite a challenge to design the module in a way that it can be produced with inexpensive materials and at the same time to have high accuracy in manufacturing. We also had to develop special tracker control algorithms to maximize output.

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Interview

How “green” is this technology?

As I mentioned earlier, we don’t need water cooling. Secondly, the energy payback time—the energy used in manufacturing the units divided by the energy production—is nine months compared to silicon-based systems, which range from 18 to 30 months.

And you have a new US subsidiary?

Yes, we opened it as the American Southwest is a perfect environment for our units—lots of sunshine, hot and dry.

We already are working on the Chevron installation in New Mexico—when it was announced in February this year, it was the largest CPV power plant in the USA. Quoting from the July 12 press release: Concentrix Solar, Inc. is based in San Diego, where Concentrix Solar installed a CPV demonstration system in July 2009 to test its solar modules under California’s climate conditions. Since its installation,

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the 6-kilowatt system has proven exceptional performance, achieving 25 percent efficiency in generating electricity.

After evaluating the market potential for Concentrix Solar’s CPV technology, the company decided to open this first U.S. office, which will be led by new general manager of business development, Clark Crawford. Previously, Crawford led sales and marketing efforts at CPV systems supplier Amonix, Inc. He has a successful track record of securing large-scale commercial orders of CPV systems, and brings his extensive experience in the solar energy market to Concentrix Solar.

As Concentrix Solar expands its presence in the U.S., the company’s multi-junction CPV module has achieved a listing with the California Energy Commission (CEC). This listing is vital to doing business in California and a key step in financing commercial projects with customer companies and state energy

utilities. Concentrix Solar’s CX-75 module has now been listed by the CEC after testing at TÜV Rheinland Photovoltaic Testing Laboratory LLC in Tempe, AZ. Concentrix has an intriguing product—lowcost, green, efficient and reliable—aimed at a target market with perfect climatic conditions for its product.

We thank Herr Lerchenmüeller for his time.

Alan Rae

Global Solar Technology – July/August 2010 – 21

Technological Show Preview:developments Intersolar North America

Technological developments Imec significantly reduces cost of germanium-based thermophotovoltaic cells Imec presents an improved processing technique for germanium-based thermophotovoltaic (TPV) cells resulting in significant reduction of cell cost, an essential step to develop a market for thermophotovoltaic applications. Imec’s

newly developed TPV cells are fabricated on germanium substrates with an optimized surface, specifically designed and manufactured for this application.

Thermophotovoltaic cells convert radiation from heat sources with a temperature lower than the sun’s temperature. TPV cells are ideally suited to be used in an industrial context, for example to generate electricity from waste heat released during steel or glass production. Alternatively, TPV cells can be added to domestic heating systems to co-generate electricity besides hot water. TPV cells may

therefore reduce the waste and hence increase the efficiency of domestic heating systems.

However, due to the overall complexity of a full TPV system and the relatively high cost of existing suitable cells, TPV systems are yet to find entrance to industrial and consumer applications.

Imec’s newly developed fabrication process is an important first step in opening up the market potential for this very promising technology.

The emission peak of selective emitters typically used in TPV systems is close to the bandgap of germanium.

Therefore, germanium photovoltaic devices are well suited as receivers for this type of systems. Germaniumbased TPV cells were up to now fabricated on epi-ready substrates marketed for the epitaxial growth of III-V layers.

However, Imec’s processing method does not involve any epitaxial deposition steps, as the emitter is formed by diffusion and passivation obtained by using amorphous Si. During a research program,

RoseStreet Lab scientists announce breakthrough multiband solar cell technology RoseStreet Labs Energy, Inc. announced a breakthrough laboratory demonstration of the first known multiband photovoltaic device featuring three distinct light absorption regions integrated into a single layer thin film device. This breakthrough is based on RSLE’s IBand™ technology and is the first known intermediate band solar cell reduced to practice in a laboratory demonstration. This technology illustrates

specifically designed Ge substrates for this application were manufactured and tested. Spectral response measurements comparing the traditional TPV cells starting from epi-ready substrates with TPV cells defined on specifically engineered Ge substrates show that the latter have a remarkably better quantum efficiency.

This directly translates into a higher waste heat to electricity conversion efficiency.

Jef Poortmans, Director Photovoltaics at imec: “Imec’s

great promise for high efficiency thin film solar efficiencies above 35% by potentially capturing the full spectrum of the sun’s spectrum.

Efficient solar cells require optimized utilization of the whole solar spectrum.

Currently this is achieved in a complex and expensive technology in which several solar cells with different band gaps are connected in series. A much simpler approach in which a single semiconductor has several different gaps sensitive to different parts of the solar spectrum has

22 – Global Solar Technology – July/August 2010

research into photovoltaics aims at finding techniques to fabricate cost efficient and more efficient solar cells. We have built up a strong expertise in silicon solar cells of more than 25 years. We successfully used this knowledge for our TPV research. We applied imec’s proprietary surface passivation techniques, novel contacting technologies and material knowledge to improve the quantum efficiency of our TPV cells, resulting in higher cell performance and cost reduction.” www.imec.be

been proposed but never realized. The intermediate band solar cell developed

by RSLE, is a thin film technology based on the discovery of highly mismatched alloys. The simple and elegant three bandgaps, one junction device has the potential of significantly improved solar light absorption and higher power output than the III-V triple junction compound semiconductor devices that presently hold the world record for solar efficiency.

RSLE’s demonstration device was fabricated on high volume CVD

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Technological developments

technology thereby validating the potential for high volume commercialization.

“Although we are three to four years away from high volume production with the IBand product,” said Bob Forcier, CEO, of RSLE, “this development opens up a new class of semiconductor devices for photovoltaic conversion and other advanced semiconductor applications.

It fits seamlessly with our Hybrid PV commercialization.”

Wladek Walukiewicz, CTO, of RSLE, added, “This demonstration is a major breakthrough in our photovoltaic semiconductor roadmap which will allow us to go to the next step in our PV research at an accelerated pace. The IBand™ technology is synergistic with our thin film Nitride Hybrid product development and will allow upside potential for higher solar conversion efficiencies compared to conventional technologies.”

RoseStreet Labs Energy, Inc. (RSLE) is a privately held firm headquartered in Phoenix, Arizona. RSLE is commercializing full spectrum photovoltaic devices for high performance applications.

RoseStreet Labs LLC, the parent company of RSLE, is a privately held supplier of products and services for the renewable energy, semiconductor and life science markets. www.rosestreetlabs.com, www.RSLEnergy.com 17.6% record efficiency flexible CIGS solar cell on plastic developed at EMPA in Switzerland Flexible thin film solar cells on polymer film with a new record efficiency of 17.6% have been developed by the scientists at the Swiss Federal Laboratories for Material Science and Technology (EMPA). The 17.6% photovoltaic conversion efficiency of the flexible solar cells has been independently certified by the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg, Germany.

Scientists under the leadership of Dr. Ayodhya N. Tiwari at the Laboratory of Thin Film and Photovoltaics, EMPA, Dübendorf, Switzerland have been developing thin film solar cells based on Cu(In,Ga)Se2 (known as CIGS) semiconductor material, and the research group while earlier working at ETH Zurich had developed 14.1% record efficiency flexible CIGS solar cells on polymer film in 2005. Now in a major breakthrough the research group at EMPA working in close collaboration with FLISOM Company (www.flisom.ch) has developed a process that resulted in a remarkably high 17.6% efficiency solar cell which is an

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independently certified highest efficiency record for any type of flexible solar cell on polymer film reported up to now.

Development of high efficiency solar cells on plastic film is challenging because most of the polymer films used as substrate lack thermal stability for growth of high electronic and structural quality CIGS solar cell layers at high temperatures. High thermal expansion coefficient of polymer causes a large stress in the layers deposited at high substrate temperature resulting in cracks and delamination of the solar cells from the substrate. Adrian Chirila, doctoral student and other colleagues, working under the supervision of Dr. Tiwari have been developing a vacuum evaporation process for growth of high quality CIGS absorber layers at sufficiently low temperature of about 450˚C that is suitable for polyimide film as a flexible substrate for roll-to-roll manufacturing.

A large improvement in the efficiency of flexible cell, from a previous record value of 14.1% to a new record of 17.6% was achieved by reducing the optical and electronic losses in the CIGS solar cell structure. The most important factor was the optimisation of the composition gradient of Ga across the CIGS layer thickness and an appropriate incorporation of Na for doping during the final stage of the growth process.

Consequently, an optimum band gap grading and larger grain size in CIGS layer resulted in a substantial increase in the efficiency of flexible solar cells. The photovoltaic measurements performed under the standard test condition at ISE Friburg confirmed 17.6% efficiency with Voc = 688 mV, Isc = 34.8 mA/cm2, FF = 73.6%.

Preliminary results of the flexible CIGS solar cell development were presented at the recent IEEE Photovoltaic Specialist Conference, 21-25 June 2010, Honolulu, Hawaii where Adrian Chirila also received a Student Award for the development of high efficiency flexible CIGS solar cells and monolithically connected solar modules developed in collaboration with FLISOM Company.

The low temperature process for CIGS deposition offers a unique advantage that the same process and equipment can be used for polymer as well as metal foils. Flexible CIGS solar cells on metal foils with highest efficiency of ca 17.5% are generally grown at high temperatures above 550˚C, while lower efficiencies were obtained on polymer films because of lower deposition temperature. The successful development of 17.6% efficiency

flexible CIGS solar cell on polymer with a low temperature process has closed the efficiency gap between the solar cells on polymer and metal foils. This solar cell processing can be adapted for roll-toroll manufacturing of monolithically connected solar modules on polymer films. Lower thermal budget and roll-to-roll manufacturing of high efficiency flexible CIGS solar cells will pave the way for substantial reduction in production cost of next generation of solar modules produced on large industrial scale in future. Learn more about EMPA at www.empa.ch/tfpv.

EVSO applauds new breakthrough increases solar cell conversion efficiency to 66% Researchers from the University of Texas in Austin and the University of Minnesota in Minneapolis have discovered a process that can be used to increase the conversion efficiency of solar cells up to 66%. The process transfers hot electrons from quantum dots to an electron acceptor.

In typical semiconductor solar cells, photons with energies above the semiconductor’s bandgap generate hot electrons, and much of the energy from the hot electrons is lost through heat before it can be captured and used for electricity. This new process uses quantum dots to slow down the cooling process of hot electrons and then captures and transfers them. This allows the addition of energy that is currently lost as heat in conventional solar cells.

“This is a dramatic leap forward in making solar power more cost efficient,” sai Robert Hines, president of Evolution Solar. “This has the potential to double solar power output and cut solar payback times in half.”

Evolution Solar is currently building a solar demonstration site in partnership with Texas Southern University, to be located at the University’s Houston Campus. Evolution Solar is also developing a solar demonstration project with the City of Brookshire, Texas. These projects should help Evolution Solar acquire new business in a sector that is growing to compete in the energy industry, which includes BP, Xcel Energy Inc., Penn West Energy Trust and the Encana Corporation. www.evolutionsolar.com.

Global Solar Technology – July/August 2010 – 23

Anayst buzz

Analyst buzz Solar energy market will grow 43% Y-o-Y in 2010, but oversupply is likely The solar energy industry experienced the proverbial “perfect storm” of marketchanging events in 2009 that redefined the rules of the game and therefore altered the competitive landscape as well.

Starting in late 2008, the solar market shifted from supply-constricted to demanddriven within a few quarters due to the plunging price of crystalline silicon cells and modules spurred by falling polysilicon cost, constrained availability of credit, Spain’s dramatic demand decline, and the growth of thin film supply and market share. According to a new white paper from Pike Research, while solar demand will experience strong growth this year, these events have had a strong influence on which companies will lead the industry in 2010 and beyond and which will face low profit margins and possible consolidation.

“The solar market is now faced with a gross oversupply of modules,” says senior analyst Dave Cavanaugh. “The industry is currently supplied by more than 190 cell and module manufacturers, making consolidation of weaker competitors an inevitable outcome.” Cavanaugh adds that,

in the meantime, overcapacity and intense competition will create downward pressure for module average selling prices (ASPs), which will accelerate grid parity for the cost of solar-produced power to the 2013 timeframe in many markets.

A few of Pike Research’s other key forecasts and findings about the new solar market include the following: • Pike Research forecasts that worldwide solar demand, driven by lower costs and greater availability of credit, will increase to 10.1 gigawatts (GW) in 2010, a year-over-year increase of almost 43%.

• The cleantech market intelligence firm also anticipates that solar market demand will exceed 19 GW by 2013, a 25% compound annual growth rate (CAGR) from 2010; this growth will be driven by demand from the United States, Italy, and China, in addition to steady demand from Germany and demand growth in a number of smaller countries.

• Excess module supply could easily reach 8.3 GW in 2010, even account-

ing for reasonable utilization rates and moderate capacity growth.

• In 2010 and beyond, the most important competitive differentiators for successful solar companies will be: (1) low cost per watt, (2) module efficiency, and (3) moving down the supply chain to provide “one-stop shopping.”

Pike Research’s paper, “The New Solar Market”, examines the new competitive differentiators that will determine success for solar companies following the market upheaval of the past two years. The report analyzes the market dynamics and implications for key companies associated with module oversupply and a large number of competitors, and provides insights on the importance of cost per watt, module efficiency, supply chain integration, and other key factors. This study also includes detailed quantitative analysis and forecasts of solar market demand and module manufacturing capacity. A full copy of the white paper is available for free download on the firm’s website www.pikeresearch.com.

German PV market could double, despite feed-in tariff cuts Despite rumors of a slow-down, the German PV market could have another banner year in 2010, setting yet another record for the world’s largest solar market.

Henning Wicht, senior director and principal analyst at iSuppli, a leading technology market research firm, predicts up to seven gigawatts will be installed in Germany in 2010. “The experiences from Spain in 2008 and Germany in the second half of 2009 indicate that the German market in 2010 can grow by 100 percent,” Wicht said. “Also, after the feed-in tariff cuts in 2010, we will still see attractive investment rates for all roof-top installations and selfconsumption. Everyday, we are anxiously awaiting new data on the monthly installation report published by the Bundesnet-

zagentur (German Grid Agency). But the exciting time is now.”

Italy may overtake Germany as the leading market, with the US, France, Japan and China soon to follow, Wicht said. “We expect numerous countries offering solar incentives which are not yet visible today.

Indeed we expect markets to shift, however, Europe will still attract approximately 60 percent of all installations.” www. thesolarfuture.com

PV during the same period, according to iSuppli Corp.

Solar thermal, or concentrated solar power (CSP), is undergoing a boom as newly installed capacity explodes. Annual global CSP installations are projected to reach 10.8 gigawatts (GW) in 2014, up from just 0.29 GW in 2009. In contrast, PV installations will amount to 45.2 GW in 2014, up from 7.0 GW in 2009.

Solar thermal: The other solar energy While most of the focus in the solar world is on photovoltaic (PV) power, the fastestgrowing segment of the solar market is actually the solar thermal market, which will expand by a factor of 37 from 2009 to 2014, compared to just a sixfold rise for

24 – Global Solar Technology – July/August 2010

Collecting the sun PV employs arrays of cells that convert the sun’s radiation into direct current electricity. On the other hand, solar thermal uses mirrors to reflect the sun’s heat energy onto collectors filled with fluids or gases.

This energy is then used to heat water and, in turn, drive a steam turbine to generate electricity. One type, the dish system,

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Analyst buzz

doesn’t use steam turbine but rather a Stirling engine that creates mechanical motion to operate an electrical generator. The most popular type is a parabolic trough version that heats a tube of synthetic oil, which is pumped through a heat exchanger to create water steam that drives a turbine electricity generator. Other types include a tower configuration with flat mirrors that reflect to a central tower collector as well as versions that use a Fresnel lens to amplify the sun’s effect. Another type, called a chimney, doesn’t use water or fluids but employs convection air currents to suck air in through turbine fans at the bottom of a tower surrounded by a greenhouselike apron of glass. CSP plants also are beginning to store the sun’s heat energy for release to steam generators at night. Forms of molten salt and graphite lead the list of storage alternatives for slowly releasing heat.

The CSP market vs. tower and dish technology “The market for CSP is currently limited, with two countries—the United States and Spain—dominating project deployments so far,” said Greg Sheppard, chief development officer at iSuppli. “About 10 projects are online at present, but by the end of 2011 the number of projects will grow to 40 with another 100 in the planning phase from 30 vendors. North Africa, China, and Australia are the next high-growth regions.

“CSP stakeholders also believe 2010 is the year when the technology could really gain traction in the market, even though companies are looking at land rights acquisitions—which progress on a much slower scale than technology evolution—while also examining water use, wildlife impact and power transmission issues that could prove to be bottlenecks for some countries, including the United States.”

Parabolic CSP might be the dominant approach at the moment, but iSuppli believes tower and dish technology will catch up in the next few years.

Solar One An example of the CSP model is The Nevada Solar One facility, which is majority owned and operated by Acciona, responsible for generating enough electricity to power 14,000 homes in the Las Vegas area. The plant, the biggest solar facility in the world when it opened in 2007, can produce up to 75 megawatts (MW). It is built on 400 acres and employs 182,000 mirrors that heat oil-based liquid to more than 750 degrees Fahrenheit. The liquid’s

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heat is then transferred to steam and drives a turbine system, which is supplied by Siemens. If more of these facilities crop up, and should the timetable for CSP be on target, another technology in the move to green energy may be at hand—one that could reduce the market’s dependency on traditional methods of generating electricity.

and China. The analysis will include definitions, current product offerings and market detail on the following segments: • Photovoltaic cells and modules • Vacuum tube and flat-panel solar thermal modules • Balance of system components including inverters, frames, batteries and charge controllers

U.S. solar panel market will reach $34.5 billion by 2014 After its best year ever in 2008, the world solar market struggled to survive a tumultuous 2009. What looked like a yawning drop for the photovoltaic (PV) market in the first half of the year turned into a solid gain in total amount of systems installed on the strength of strong German sales in the fourth quarter. But despite annual worldwide PV installations rising from 5.8 GW in 2008 to 6.6 GW in 2009, the PV market value dropped by 15.8% to $17.0 billion due to crashing PV cell and module prices.

The U.S. fared better than most countries, with the PV market up an estimated 6.0% in 2009 to $3.5 billion and PV installations rising to 469 MW. An extension of the solar tax credit and new recovery act funding helped to keep the U.S. PV market on a continuing upward trend. The U.S. represented only 1% of a world solar thermal collector market dominated by China in 2009, shipping 1.0 GW of collectors worth $79.6 million.

While still currently focused on low temperature pool heating systems that represented 82% of the U.S. market (by megawatts of collectors shipped) in 2009, SBI Energy anticipates much stronger growth in residential hot water systems heading to 2014. Worldwide, the U.S. still has the greatest potential to increase its position in the solar market.

SBI Energy foresees 900 MW of PV installations in 2010, rising to 7,600 MW of PV installations in 2014 building on renewed interest in solar from utilities and the extension of the solar tax credit. While the ST market will show only moderate growth in the U.S., the PV market segment will continue to shine in the U.S. and the concentrated solar power (CSP) market is set to explode. SBI Energy estimates the U.S. solar panel market will reach $34.5 billion in 2014. U.S. Solar Energy Market World Data, 2nd Edition by SBI Energy analyzes the manufacturing and sales of the U.S. solar photovoltaic and solar thermal markets within the context of other key solar countries such as the Germany, Spain, Japan

Solarbuzz raises global photovoltaic 2010 market forecast to 15.2 GW Global photovoltaic demand continues to soar in 2010 and is currently projected to double over the rate of installations last year, according to Solarbuzz®, an international solar energy market research and consulting company.

In the latest edition of the Solarbuzz® QUARTERLY Report, Solarbuzz has raised its 2010 market size to 15.2 GW, which compares with a revised 7.5 GW in 2009.

Specifically, the last three quarters of 2010 are projected to generate 12.7 GW, driven by strong growth across Europe, but also in the United States, Japan, China and a range of smaller start-up markets. German market demand incorporates substantial volatility in Q/Q performance during 2010. This takes into account the uncertainty of policy adjustments in Germany that are planned for July 2010 and also January 2011. A 2010 market size of 8 GW in Germany is now in prospect, even taking account of a drop off in demand in Q3’10.

“Despite much uncertainty over policy outcomes, a challenging economic environment and inverter supply, the PV industry is once again demonstrating that consumers respond to supportive government policies,” said Craig Stevens, president of Solarbuzz. “The growth in demand is a response to major cuts in price levels afforded by lower manufacturing costs. As a result, module and inverter supply is just barely keeping up with demand.”

Preliminary data on global industry revenues shows a drop of 40% to just over $12 billion in Q1’10, which was nearly four times the level one year earlier.

Selected price rises late in Q2’10 have been seen from some Chinese manufacturers supplying to Europe. These moves helped to partially offset the decline in the euro over Q2’10.

Within the PV chain, wafer prices have tightened in both euro and US dollar terms, while cell prices have tightened in euro terms only over the past six months.

Global Solar Technology – July/August 2010 – 25

Title New Products

New products Indium Corporation introduces tabbing and bus ribbon kits Indium Corporation’s newly designed tabbing and bus ribbon kits, which contain common sized tabbing and bus ribbon as well as fluxes, are available in three versions, including one with a uniquely designed Pb-free, bismuth-containing, lowtemperature coating.

“The kits are a valuable tool for scientists and engineers to efficiently experiment with different coatings and fluxes at both traditional and low temperatures in an easy-to-handle, low-cost kit system,” said Bill Jackson, director of solar products. “The fluxes are designed to work in both manual and automated assembly processes.”

The three versions of the kit include tin/silver, bismuth/tin and tin/lead/silver and can be ordered through Indium’s easy online ordering system.

The fluxes were developed by Indium Corporation’s award-winning research & development team. This team, led by Dr. Ning-Cheng Lee, has been designing fluxes for high reliability and longevity, including the solar, medical, aerospace, automotive, and communication industries for over 25 years. www.indium.com Raytek MI3 series noncontact infrared temperature sensors Measuring the temperature distribution of the film deposition and the substrate of the solar panel is critical in this process. A high resolution thermal image of the entire panel surface allows proper tuning of the ovens used in the deposition process (sputtering, printing).

Non-uniform temperature profiles or improper process temperatures can lead to voids and poor PV module performance and failure. Raytek’s new MI3 Series of infrared temperature measurement sensors represents a new generation of performance and innovation in noncontact temperature monitoring. The Raytek MI3 sensors deliver industry-leading performance and flexibility at the lowest installed cost per measurement point.

Combining a rugged IP65 (NEMA 4) stainless steel sensing head with a separate communication module, the MI3 is designed to meet virtually any noncontact temperature measurement requirement.

According to Bill Kolbeck, Raytek

New conductive adhesive for PV cures fast at low temperature Delivering a robust alternative to high-temperature solder processes, Henkel has developed Hysol ECCOBOND CA3556HF, a silver-filled electrically conductive adhesive designed to offer fast cure at low temperature. The material is ideal for high-throughput production processes and applications that dictate high peel strength, such as the assembly of photovoltaic (PV) modules, automotive sensors and membrane switches that incorporate temperature-sensitive substrates.

While solder is arguably the most common electrical interconnect material, its high temperature requirements make it impractical for certain applications. Fragile, thin, temperature-sensitive substrates are often subject to damage not only from the requisite soldering temperatures, but also from screen and stencil printing processes themselves. Hysol ECCOBOND CA3556HF resolves these issues with fast, low temperature curing.

“This material is not just a superior replacement for solder in certain applications,” said Vito Buffa, Henkel global product manager for pastes and inks. “Hysol ECCOBOND CA3556HF also has advantages over other electrically conductive adhesives that burden users with long cure times and limited flexibility.

This material’s cure speed and versatility are unmatched.”

Initially designed to address the unique requirements of the photovoltaic module assembly market, Hysol ECCOBOND CA3556HF has been proven for other processes, too. It’s flexibility for the photovoltaic sector is well-documented, as it is suitable for both crystalline-silicon (c-Si) and thin film manufacturing. For c-Si cell production, Hysol ECCOBOND CA3556HF delivers an excellent bond between the Ag and SnPbAg coated tabs and the c-Si cells. Thin film module manufacturers seeking a low-stress, fast cure electrical interconnection of cells with ribbons have also incorporated the material into their processes with great success. www.henkel.com/ electronics

product manager—point sensor products, infrared thermometers, such as the MI3, are the fastest, safest and most cost-effective way to measure critical temperatures

26 – Global Solar Technology – July/August 2010

necessary for process control and automation. “Energy costs are typically one of the top three operating expenses in any manufacturing facility, and process heating

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New Products

Advanced automation for solar, LED and chip packaging factories The new Applied SmartFactory MES software from Applied Materials is an affordable, out-of-the-box factory automation solution to track and streamline the flow of materials throughout a manufacturing facility.

Designed to help accelerate the production ramp of emerging technologies in the solar, LED and chip packaging industries, SmartFactory can be deployed in less than 60 days to improve product quality, boost productivity and cut operational costs.

SmartFactory is also the first MES available with integrated advanced process control (APC) capability, enabling customers to achieve higher and more consistent factory output.

“The SmartFactory system is designed to help factory operations in rapidlygrowing industries achieve the high yields and economies of scale that can lower manufacturing cost—key to the widespread adoption of these important new technologies,” said Charlie Pappis, vice president and general manager of Applied Global Services. “With the SmartFactory system, customers can realize the benefits of Applied’s proven manufacturing automation technology with a ready-to-use

is the largest portion of this expense,” optically isolated relay allows for local said Kolbeck. “The Raytek MI3 reduces alarm capability, eliminating the need for energy costs by allowing tighter process separate limit switches or alarms. Other control and more efficient process heating. standard MI3 features include: adjustable Improved control performance usually emissivity, transmissivity, peak hold, results in less product variation, higher valley hold and signal averaging, and product quality and increased throughput.” configurable inputs for emissivity control, Kolbeck indicated the new MI3 sensor ambient background compensation and provides all the functionality of the proven trigger/hold input. www.raytek.com Raytek MI Series with significant new features. These include a broad choice of sensing head temperature ranges and spectral responses, a standard USB 2.0 Atlas SEPAP 12/24 now available worldwide digital interface for easy sensor set-up Atlas’ SEPAP 12/24, a medium pressure mercury arc testing instrument, is now and configuration, a fully programmable available worldwide. This affordable, accelerated photoaging device examines electronics platform, and response times photodegradation mechanisms of polymeric formulations in laboratory conditions. as fast as 20 mSec. The thermometer’s Primarily sold in France previously, Atlas is now launching the device globally due to innovative multiple sensing head increased demand in other markets. interface supports up to eight individually Designed as an analytical tool to understand the degradation mechanisms of addressable heads per communication box. naturally aging polymers at the molecular level, the SEPAP 12/24 unit replicates the The Raytek MI3 Series sensors offer a chemical changes in accelerated, controlled lab conditions that are achieved through choice of scalable 0/4 to 20 mA and 0 to long-term, natural weathering conditions, from which similar changes in macroscopic 5/10 VDC analog outputs, or Type J, K, R properties (mechanical, aesthetical, etc.) can be expected. Use of the SEPAP 12/24 or S thermocouple outputs, as well as an unit is largely accepted by standards committees and by industrial companies in fields optional RS485 network interface – thus, where long-term quality control is highly stringent such as: enabling seamless integration into existing • Automotive control equipment or OEM systems.

• Sport equipment Standard USB 2.0 communication • Plasticulture equipment facilitates sensor configuration and is • Electrical valuable for troubleshooting when the • Building device is installed in hostile or remote • Industrial Packaging locations. Additionally, this capability SEPAP 12/24’s design relies on fundamental concepts of macromolecular saves maintenance time and minimizes photochemistry. The units are built as parallelepiped chambers with four medium technician exposure to hazardous pressure mercury arc lamps in borosilicate envelops that emit discrete radiation at environments. Robust field calibration 290, 313, 365, 405, 436, 547, and 579 nm. The light source is not used to simulate software also allows on-site calibration of daylight, but to induce the same photochemical processes as daylight. Samples are sensors, which further reduces service time homogeneously exposed on a rotating support in the center of the chamber. The and expense. surface temperature of the samples is accurately controlled and maintained between The MI3’s user-programmable, isolated 50 and 80°C ±1°C through a thermocouple placed behind a reference film with same alarm output is an easy way to achieve color and chemical composition as the exposed samples. www.atlas-mts.com alarm and control redundancy or provide DuPont™ PV5223 thin white reflective encapsulent sheets. simple on/off control capabilities.

Its

www.globalsolartechnology.com

Global Solar Technology – July/August 2010 – 27

New Products

solution that can be expanded as their businesses and industries grow without disrupting ongoing production.”

Based on Applied’s leading FAB300® MES technology, the SmartFactory system features pre-built, technology-specific scenarios to monitor every machine and all work-in-progress material movements, manage production sequencing, create an audit trail, and deliver instructions to shop floor workers via a consistent, task-focused graphical user interface. The SmartFactory system’s optional APC module uses Applied E3™ technology to interface directly with production equipment, enabling real-time, run-to-run (R2R) process tuning and fault detection and classification (FDC) to increase process capability and reduce unplanned down time. Applied’s common framework approach allows the SmartFactory system to be expanded with plug-in components from Applied’s leading portfolio of factory automation software, proven in over 500 manufacturing facilities worldwide. Statistical process control, equipment performance tracking, advanced dispatching and RFID wireless management capabilities can be rapidly added to further raise manufacturing efficiency. www.appliedmaterials.com BioSolar begins sales of commercial grade BioBacksheet BioSolar, Inc., officially commenced high volume commercial production and sales of its unique bio-based backsheet for solar materials. The BioBacksheet™ is a protective backing for photovoltaic (PV) solar modules that replaces current expensive and environmentally hazardous petroleum-based backsheets.

“This day has been four years in the making,” said Dr. David Lee, CEO of BioSolar. “We have finally completed the development of the world’s first commercial grade green backsheet and are ramping up production and are able to accept and fulfill orders. Over the past month, we have been demonstrating the BioBacksheet™ to major solar panel manufacturers. They are all excited about the BioBacksheet™ due to its high durability and improved performance over other backsheets on the market, and have requested large quantities for full scale integration trials into their solar panel production lines.”

The primary material for the commercial grade BioBacksheet™ is a durable polyamide resin made from castor beans, which is then compounded with a secondary non-petroleum material during

New high efficiency Solamet photovoltaic metallization pastes DuPont Microcircuit Materials (MCM) has introduced its newest generation of frontside metallization pastes for crystalline silicon solar cells—DuPont™ Solamet® PV16x series photovoltaic metallizations. This advanced series outperforms previous generation products by delivering up to 0.4 percent greater conversion efficiency for solar cells. PV16x series photovoltaic metallizations are also suitable for a wide range of printing line widths and processes, which help to meet a variety of photovoltaic market needs.

“DuPont™ Solamet® has consistently raised the bar for efficiency, setting increasingly higher standards by enabling customers to reduce costs and enhance the competitiveness of their products,” said Walt Cheng, global business director.

“For over 20 years, DuPont research scientists have been advancing photovoltaic cell efficiency, helping our customers in the industry reach grid parity.”

DuPont™ Solamet® PV16x series photovoltaic metallization pastes can provide up to 0.4 percent greater efficiency, and features low-contact resistance. They are available in a range of options suitable for various printing requirements, including fine lines (less than 80µm) with high aspect ratio patterning, improving line conductance. They are capable of contacting shallow emitters of up to 85 ohms/sq and deep emitters as well.

Solamet® PV16x photovoltaic metallization pastes have undergone extensive customer testing. DuPont first featured new Solamet® PV16x series metallization pastes as part of its broad and growing portfolio of photovoltaic solutions at the 2010 SNEC 4th International Photovoltaic (PV) Power Generation Conference & Exhibition in Shanghai, China, and is now introducing the series in the Americas, Europe and Japan. DuPont Microcircuit Materials was recently awarded the United Kingdom’s prestigious Queen’s Award of Enterprise in the Innovation category for its continuous development of DuPont™ Solamet® photovoltaic metallization pastes as a key component in increasing the energy efficiency of solar cells, and for increasing the effectiveness of photovoltaic solar cell technology. photovoltaics.dupont.com

28 – Global Solar Technology – July/August 2010

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New Products

the extrusion process to form a unique and highly durable PV backsheet film which, in addition to being “green,” has several additional advantages over other commercial backsheet films.

“BioBacksheet’s monolithic (single layer) construction does not exhibit interlayer de-lamination, a common problem in conventional laminated backsheets,” said Dr. Stanley B. Levy, chief technology officer. “Therefore, it is more reliable than backsheets on the market today and we have received raving reviews from PV manufacturers about this feature. In addition to the use of renewable biobased materials, BioBacksheet’s durability characteristics are equal to or better than those of multi-layer conventional petroleum based backsheets. Most importantly, it is more cost effective when compared with similar grades of conventional petroleum-based backsheets.” www.biosolar.com New vacuum pump for solar panel manufacturing Edwards introduced a new GXS dry pump designed to support pumping requirements for silicon ingot manufacturing and laminator applications in the solar industry. The GXS provides the optimized thermal control and dust handling capability needed to meet the pumping challenges encountered in these processes.

The high atmospheric pumping speed capability of the GXS also enables faster chamber pump down, reducing cycle times and improving throughput.

“This new GXS dry pump has been optimized to meet the specific pumping process requirements for solar laminator and crystal pulling applications,” said Dr. Allister Watson, solar and flat panel display dry pump product manager at Edwards. “Its closed-loop thermal management system ensures the pump remains at the optimal temperature to prevent pump seize-ups, due to either glue condensation in laminator applications or overheating when pumping high concentrations of argon during crystal pulling applications. At the same time, its fast pump down time, low utility consumption and reduced maintenance all contribute to a low cost of ownership.”

The new GXS uses a tapered variable pitch screw profile (patent pending) that allows for tight clearances without the need for rotor coatings. It also enables compression variations along the rotor axis for improved thermal stability and better thermal control, making it an optimal pump to handle the high flows of argon

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gas used in crystal pulling applications, as well as the dust generated during the manufacturing process.

The GXS dry pump can operate on as little as 3.9 kW of input power (depending on the pump version) and uses 57 percent less energy than competing piston pumps. The high efficiency motors are inverter driven and enable reduced energy by running in idle mode, allowing further cost of ownership savings. Inert, non oxidizing oil is used to lubricate the gears and bearings of the pump with no maintenance required between major services (unlike grease packed bearings). No oil within the pumping mechanism means no need for frequent and costly oil changes, unlike oil sealed rotary vane pumps. A small footprint (approx. 0.4m W x 1.1m L x 0.8m H), less than 50 percent of competing pumps, saves valuable production space, while the low noise (<64 db(A)) eliminates the need for silencers and allows pumps to be located close to customers’ chambers, if required. The GXS pump is compatible with Edwards Fabworks data monitoring system, so that pump parameters can be monitored and trended in real-time via a central computer. www.edwardsvacuum.com Christopher Associates to distribute new photovoltaic module backing films Jolywood (Suzhou) Solar Materials Technology Co. Ltd. of China, in cooperation with Hangzhou University, has developed an exciting new range of FFC/PET/FFC photovoltaic backing films that offer superior performance at a lower long-term cost than most materials on the market today. A number of leading manufacturers have already adopted these materials into their module manufacturing operations. The Jolywood films are UL, TüV and SGS listed and are available in North and Central America through Christopher Associates. www.jolywood.cn, www.christopherweb.com

Electrolube powers ahead with photovoltaic products Electrolube resins such as ER2074 (thermally conductive epoxy), HTCX (thermally conductive paste) and UR5528 (tough polyurethane with excellent adhesion to a variety of substrates) are ideal for the protection of photovoltaic systems. Additionally, Electrolube produce a range of clear encapsulation resins and conformal coatings, such as UR5562 and the new toluene free acrylic, TFA, which too are ideal for the protection of environmental ingress.

Electrolube will continue to offer products to assist in the development of renewable energy technologies and will ensure the development of innovative environmentally and user-friendly chemical products for the electronics industry. www.electrolube.com

Global Solar Technology – July/August 2010 – 29

New Products

Super acceleration UV weathering chamber EYE Lighting International of North America, a subsidiary of Iwasaki Electric Co. Ltd., introduced a new super acceleration UV durability/weathering system that provides the fastest acceleration rate in the industry. UV and weather durability testing is a necessity for any product that must endure the harsh treatment of Mother Nature.

UV rays are the greatest cause of product deterioration. With solar module useful life expectancy now reaching beyond 30 years, laminate materials and components must be tested to verify durability under extended outdoor exposure. Faster accelerated life testing allows manufacturers to make product adjustments sooner in the development process.

EYE’s SUV-W151 super acceleration UV chamber provides acceleration factors more than 10 times typical Xenon chambers. With the capability to deliver more than 30 times natural sunlight UV energy, this system can simulate three years of outdoor exposure in only nine days of testing. Correlated acceleration factors up to 100 times natural solar UV irradiation provide proven, extended outdoor exposure evaluation testing. Custom spectral filtering cuts UV irradiation below 295 nm to replicate natural sunlight and an electronic feedback system ensures constant energy to target material.

The system includes a built in data-logger for data storage and simple transfer to common programs such as MS-Excel. All weathering parameters and cycle functions are fully programmable including temperature, humidity, rainfall, UV power, rest (night time), and cycle/ duration timing. Regardless of the product, this system can dramatically reduce testing time, improving quality and profitability. www.eyelighting.com Despatch Industries VOC Thermal Oxidizer exceeds performance expectations Despatch Industries announces that it has sold over 100 VOC Thermal Oxidizer units. Customer feedback confirms that installed tools are exceeding performance expectations by completely eliminating VOC-related maintenance. The patented VOC Thermal Oxidizer is designed and engineered to destroy over 99% of VOCs from gasses exhausted during the drying of photovoltaic metallization pastes in solar cell manufacturing. The tool was developed as a direct replacement for

SABIC’s unique resins give PV customers cost-productivity and global regulatory compliance SABIC Innovative Plastics’ Noryl and Lexan EXL resins offer customers exceptional ease in solar panel use and greater cost-efficiency, and meet stringent global regulatory standards. Applications for SABIC Innovative Plastics’ materials range from PV frames to junction boxes to connectors, and the company continues to focus R&D efforts on new back sheet solutions.

Noryl resin provides low density, dimensional stability over a wide temperature range (-40˚C to 140˚C), low warpage, excellent long-term weathering, damp heat performance with exceptional stability of up to 2,000 hours, and outstanding electrical and thermal performance. These properties make it suitable for use in PV junction boxes. Noryl resin also meets the industry’s critical need for a long-lasting, outdoor-resistant material. Internal tests show that glass-filled and unfilled Noryl resins can already withstand 12,000 hours of UV exposure (which translates to approximately 10 years of outdoor weathering in Florida) with virtually no change in properties. Further testing is ongoing.

Lexan EXL resin demonstrates excellent low-temperature ductility (-60˚C to 140˚C) combined with long-term weathering and thermal performance, making it an outstanding choice for use in PV connectors. The long-term high-temperature performance of both Noryl and Lexan EXL resins is evident by their UL Relative Thermal Index (RTI) ratings of 105˚C to 115˚C. Complete UL Yellow cards are available for both products, demonstrating compliance with requirements such as UL94 V-0, CTI class, f1 and 5V-A ratings. During processing Noryl and Lexan EXL resins demonstrate stability and high productivity when compared to metal or semicrystalline plastics, and achieve cycle time reductions up to 20 percent.

Ultem resins and LNP specialty compounds are also being used for internal junction box parts and special connectors. Temperatures in these applications may go up to 180C or beyond and dimensional stability requirements are even more stringent. Commercial grades of Ultem resin and LNP compounds have been implemented successfully in PV applications from key industry players. www.sabic-ip.com

current ineffective abatement and VOC condenser options.

The Oxidizer mounts directly to the furnace to eliminate any risk of solvent condensation. Oxidizers are located at the entrance and exit of the dryer section to achieve more effective abatement with faster belt speeds. This solution also meets

30 – Global Solar Technology – July/August 2010

legal and environmental requirements regarding the capture and destruction of organic materials.

The VOC Thermal Oxidizer is included on new UltraFlexä and is an available option on CF Series firing furnaces. Despatch Industries designs and engineers market-leading tools and

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New Products Solar_Photon_AD_Mar2010:Show2 8/3/10 11:24 AM Page 1

technology for the solar cell manufacturing industry. www.despatch.com Krayden, Inc. introduces Dow Corning Solar Solutions’ PV cell and module coating Krayden, Inc., recently introduced the 1-2577 low VOC coating manufactured

by Dow Corning Solar Solutions. Dow Corning 1-2577 is a silicone solvent-based moisture cure that can be accelerated with mild heat to provide faster curing times. Additionally, it is ideal for use as a photovoltaic (PV) cell and module coating because of its resistance to humidity and other harsh environments. This solar panel coating also offers excellent abrasion resistance and has good dielectric properties. The clear Dow Corning 1-2577 cures with a hard slick surface, and is mil spec and UL approved. The one-part RTV also contains a UV indicator and adheres to metal, aluminum, ceramic and plastic.

For flexibility and ease of use, the product is available in bottles, pails and drums.

Krayden, Inc. is an authorized distributor for the Dow Corning Solar Solutions’ PVbased silicone materials. www.krayden.com Yamaichi Hermetic Sealed connector TÜV and UL tested Photovoltaic connectors connect up photovoltaic modules. They play a decisive role in the efficient running of photovoltaic systems. And they need to be both reliable and cost effective. Reduced overall costs and no compromises in safety and functionality are the goal of the systems operators. Yamaichi Electronics has developed its Hermetic Sealed technology especially to meet these requirements.

The secret lies in the IP68 leak-proof overmold of cable and contact in one working process. Contrary to traditional connectors no single parts or fittings are required. The installer receives the finished assembled and tested cable from Yamaichi, tailored to his application. Costly on-site crimping or cable cutting is not needed.

Yamaichi connectors are used worldwide in photovoltaic systems. They are tested by the TÜV Rhineland and UL and carry the appropriate photovoltaic testing label. www.yamaichi.eu New generation of grindingmachines for brick production The Arnold Gruppe introduced a new generation of surface and chamfering grinding machines. With extensive improvements in the area of material and construction, the process reliability of this new generation of machines has

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been improved even further, to significantly reduce production costs whilst increasing quality. Furthermore the product portfolio has been broadened by a combined surface and chamfering grinding machine.

Arnold supports photovoltaic New Temperature Profiling Systems manufacturers, for Photovoltaic Cell and Module reducing their Manufacturers production costs Datapaq® SolarPaq systems with Insight™ considerably, Software provide complete, easy-to-use solutions enabling them to for profiling your solar process: achieve the goal • Cell anti-reflection coating of international • Contact firing competitiveness via • Module laminating grid parity.

To learn more about how our systems can The new surface save you time and money, visit us at and chamfering Glasstec, Booth #12E13 in Dusseldorf grinding machine September 28th thru October 1st. type 72/865 is specifically designed DATAPAQ, Inc. for low and Tel: 978 988 9000 E-mail: sales@datapaq.com middle range brick www.datapaq.com production capacities and complements The Worldwide Leader in Temperature Profiling the proven single machines for mechanical analysis and storage of the process data surface and chamfer processing perfectly. provided by the combined machine, is The considerably more solid machine optionally available. www.arnold-gruppe.de construction—the process element of the machine is filled with mineral STMicroelectronics innovation cast—provides a by a factor of ten recovers power lost due to solarimproved machine rigidity and increased panel variability attenuation.

STMicroelectronics unveiled the industry’s A new coolant supply with a pressure first IC to combine important powerof up to 25bar additionally provides optimization and power-conversion optimal process cooling and at the same functions for solar generators. ST’s time reduces the water consumption by innovation will allow multi-panel arrays, approx. a third. This way optimum process ranging from domestic rooftop-type reliability, shorter processing times and equipment to larger installations, to deliver more precise brick production can be more energy at a lower cost per watt. ST’s guaranteed. The database-based and webnew SPV1020 chip allows maximum browser-controllable software tool ARPAT, power-point tracking (MPPT) to be developed by Arnold for the acquisition, applied individually for each panel. MPPT automatically adjusts a solar generator’s output circuitry to compensate for power fluctuations resulting from varying solar intensity, shadowing, temperature change, panel mismatch, or ageing.

Without MPPT, the power from a solar panel can fall by 10 to 20 percent if even a small percentage of its surface is in shadow.

This disproportionate decrease may restrict the choice of site or force the use of a

Global Solar Technology – July/August 2010 – 31

New Products

smaller array to avoid shadows. In some cases, it can challenge the viability of the project. The SPV1020 enables Distributed MPPT (DMPPT), which compensates each panel individually, in contrast to a centralized MPPT scheme that applies a ‘best-fit’ compensation to all the panels in the array. DMPPT is the most promising technique to improve the energy productivity of photovoltaic systems because it maximizes the power extracted from each panel regardless of adjacent module performance, even if a module has failed.

Implementing DMPPT usually requires a network of discrete components for each panel in an array. The SPV1020 replaces this network with a single chip and also integrates the DC/DC converter to step-up

the panel’s low-voltage DC output to a larger DC voltage from which line-quality AC power is produced. By integrating MPPT and the DC/DC converter, the SPV1020 dramatically simplifies design and reduces part count, making DMPPT economical for solar generators across a range of power ratings and price points.

ST has integrated all of the required functions in a monolithic chip using its advanced 0.18-micron BCD8 multi-power process technology. BCD8 holds the key to combining power and analog functions for the DC/DC converter on the same chip as the digital logic performing the MPPT algorithm. This technology enables a smaller, more reliable and longer-lasting solution than an alternative built with discrete components. The IC also has an

advanced DC/DC converter architecture that minimizes the size and number of external passive components needed. www.st.com

DKFP extended range of currentcompensated chokes The new DKFP current compensated chokes are highly effective in suppressing common-mode interfere. The chokes may be used in line filter circuits, frequency converters, switch-mode power supplies and solar converters. The rated voltage of the DKFP compensated chokes is 250 VAC, and the chokes, which are available in vertical or horizontal versions, are designed for temperatures of between -40˚C and 125˚C. The chokes are available in vertical or horizontal versions. www.schurter.ch

Fast in-line solar cell inspection with asymmetric homogeneous diode laser illumination Illumination systems for analyzing surface properties are often located perpendicular to the inspected surface. Therefore, the solar cell has to be illuminated under a certain angle to improve the signal. LIMO has developed a diode laser that generates photoluminescence and thermographic signals by asymmetric homogeneous illumination of the solar cell. The 120 W fiber-coupled industrial laser system LIMO120-F400-SL808-103 is combined with the processing head IOS00019x-series.

This device generates a homogeneously illuminated field under 35° angle of incident that fits to solar cell sizes up to 210 x 210 mm. The center wavelength of 790…808 nm is essential for the separation of excitation source and signal light. In addition, small bandwidth versions (< 1 nm) are available as an option. Solar cell inspection tools based on the LIMO laser source operate with a single light source compared to other inspection tools using two light sources. That makes the tools more compact and reduces materials as well as assembly costs.

A special advantage of an in-line inspection tool: The quality inspection of the solar cells occurs at the full production speed without interrupting the production.

Those advantages guarantee high productivity and low cost per tested unit.

Homogeneously illuminated fields create value in metrology applications in a variety of industries, including medicine or chemical analysis. www.limo.de

32 – Global Solar Technology – July/August 2010

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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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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

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

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

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SOLAR INTEGRATION TAKES A PAGE FROM THE SEMI WAFER CSP PLAYBOOK

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Higher efficiency in solar technology

Higher efficiency in solar technology A special report from solarpeq The efficiency of photovoltaic modules is far from being exhausted. Companies are fighting on many fronts to gain percentage points. In addition to the cells themselves and the production process, the focus is also on modular glass.

The latest developments in glass technology offer additional efficiency improvements, and there are many as yet unexploited possibilities.

Californian solar producer Sunpower defends its position as innovation driver in the photovoltaics (PV) sector. In an industry-oriented production process, the company has developed a solar cell that converts sunlight into power with an efficiency level of 24.2 percent. Thus the Americans have improved the efficiency of their cells by four percentage points over the past five years and are now closing in on the world record set by the University of New South Wales in Sydney. By the late nineties, Australian researchers had already developed a silicon cell with an efficiency level of 24.7 percent. Sunpower’s key to high efficiency is the back-contact concept. “We banish all power connections of our monocrystalline silicon solar cells to the backside,” explains technologist Bill Mulligan. Therefore the front of the cells, which is facing the light, is not shaded by metal tracks, and more light is available for energy production. Due to its excellent performance, this technology is highly sought after. Backside collectors manufactured in serial production achieve an efficiency level of just under 23 percent—and a level of 19.5 percent relating to the module. Common silicon panels achieve an average of 13 to 16 percent.

More than any other factor, the efficiency level affects economic efficiency during the production of cells and modules. As a rule of thumb, each percentage point of increased efficiency lowers the costs by approximately 5 percent, as less material is used per watt.

For Sunpower, however, this cost-reducing effect does not apply because of the expensive monocrystalline semiconductor and the cost-intensive mode of production.

Backside collectors carry both the negative and the positive pole on the backside.

Therefore they must be interlaced in order

Focus on innovation: The search for more efficient semiconductors for solar cells concerns researchers and engineers all over the world (Source: Bosch)

to avoid short circuiting. “This requires additional process steps and lots of know how,” says Jan Schmidt, Institut für Solarenergieforschung (Institute for Solar Energy Research) in Hamelin (ISFH).

Improved efficiency with hi-tech glass Companies are feverishly researching more cost-efficient alternatives. The Japanese company Sanyo, for example, has developed a mono-cell that is surrounded by layers of cost-efficient amorphous silicon.

These layers mainly function as a barrier that prevents the charge that carriers produce inside the crystal from being lost at the surface. This increases the efficiency of the cells to 20.7 percent, and the modules manage and output of 18.2 percent. Alfasolar from Hanover, on the

34 – Global Solar Technology – July/August 2010

other hand, focuses on optimizing the module itself. The company uses multicrystalline cells produced by the Belgian company Photovoltech that offer up to 17 percent efficiency and packages these little powerhouses behind modular glass with pyramid-shaped structures. Thus, exiting rays are reflected on the inside of the glass in such a manner that they again meet the cells and are given a new chance for absorption if they have not been converted into power upon first contact with the silicon.

Using this technology, Alfasolar generates maximum power from the cells. The efficiency of the modules is 15.4 percent.

In the meantime, more and more manufacturers are using anti-reflective glass to improve efficiency, and light traps are only one way to better exploit the photons. For example, Centrosolar

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Higher efficiency in solar technology

exactly with the sun, which increases costs and is almost impossible for roof-mounted systems.

Complex production: The production of solar cells and modules requires extensive process know-how. For this reason, it can take years before new developments can go into serial production. (Source: aleo solar)

Delicate goods: The production of thin-film modules takes place in the clean-room. Even smallest impurities affect the efficiency. (Source: Inventux)

Glas from Fürth adds tiny air-pores to the anti-reflective layers of its glass, which allow for a softer transition of the light.

Structured and coated solar glass offers a further advantage. Its surface is smoother than conventional glass, as it is heavily compressed in a rolling process. For this reason, dirt and water roll off like they would on a lotus flower and do not affect the incidence of light. Glass specialists will show their innovations at the leading international trade fair of the glass industry, glasstec, from 28 September to 01 October 2010, or during the trade fair for solar production technology, solarpeq.

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Both events are held simultaneously in Düsseldorf.

In the case of concentrated PV, the focus is also on clever channelling of the light. The modules contain mirrors or lenses that concentrate the rays onto one tiny cell. The most effective among them achieve efficiencies of up to 40 percent.

“In good locations, concentrator systems can already produce cheaper power than traditional flat modules,” says Andreas Bett, manager of the solar cell department at the Fraunhofer Institute for Solar Energy Systems (ISE) in Freiburg. However, concentrator modules must be aligned

Nano-size solar cells The competition is also very active in the sector of thin-film technology. The highest efficiency potential is attributed to CIS cells. This abbreviation refers to semi conducting compounds of copper, indium, gallium, selenium or sulphur. This way, the National Renewable Energy Laboratory of the USA achieved an efficiency of 20.3 percent. However, industrially produced cells still have a long way to go, and with regards to production costs, they have not yet moved ahead of the crystalline competition. “As far as CIS is concerned, the existing production units are still too small.

Once mass production has started, the costs will decrease,” says EU energy expert Arnulf Jäger-Waldau. Thin-film modules made of cadmium telluride are developed further. The U.S. company First Solar is already producing them for € 0.60 per watt.

Very few manufacturers produce modules for less than one euro per watt.

Nano cells offer another option for PV. Here, tiny plastic or pigment particles convert light into energy. Heliatek from Dresden, for example, has developed a process in which pigment molecules are extensively applied to plastic foils using vacuum evaporation. Since this procedure uses little material and energy, the production costs are falling. The Saxons are aiming at € 0.40 per watt, which would be far below the costs of conventional solar modules. However, one major weakness of the nano cells is that they lose their efficiency quickly since the polymers and pigments used as semiconductors deteriorate rapidly.

Because of the many applications possible, researchers are working on improving the durability. Thanks to their low weight and their flexibility, the slim power generators can easily be integrated into buildings as power-producing glass façades or windows. Experts forecast major growth potential for the market segment of building integration. Nano PV offers a new field of activity to machinery and plant manufacturers. Companies such as Centrotherm, Leybold Optics or Von Ardenne, all of which will show their innovations at solarpeq, are already supplying thin-film producers and manufacturers of organic light emitting diodes (OLED) with coating systems.

These machines will also be requested increasingly by manufacturers of organic or pigment cells. At the special exhibition

Global Solar Technology – July/August 2010 – 35

Higher efficiency in solar technology

Follow the sun: Concentrating systems follow the course of the sun. This tracking adds expenses, but the systems produce more power than simple modules. (Source: Concentrix Solar)

glass technology live, held in conjunction with glasstec, examples of aesthetic façade-integrated photovoltaics or multifunctional façades will be on display.

Silicon continues to dominate Despite the large potential for development of thin-film technology and similar processes, Stefan Glunz, manager of the Department for the Development of Silicon Solar Cells at the ISE, believes in the future of silicon cells. He thinks that their long-term stability is undisputed and their efficiency can be improved with little effort. Efficiency increases of one percent can only be achieved if better anti-reflective layers can make use of more radiation and new, so-called passivation layers can counteract losses in the charge carriers on the surface of the crystals. New methods for the production of cell contacts are also helpful. Nowadays, frontal contacts are produced most often by screen printing using metallic pastes. The wide contact fingers thus produced impede the incidence of light and offer higher resistance. In addition, high forces are produced during printing, and only thicker cells are able to withstand the pressure. Therefore, the ISE is developing metallization processes that do not require screen printing. “We are focusing on the chemical separation of metals or the contactless printing of metal aerosols,” says Glunz.

Further efficiency improvements are promised by “N-type” silicon, a positive conductive absorber enriched with boron.

This special variant of silicon offers particularly good electrical characteristics, however, it is difficult to handle in production because of the highly reactive boron. An optimal passivation of N-type cells cannot be achieved with traditional barrier levels. In cooperation with the Energy Research Centre of the Netherlands (ECN) and US systems producer Amtech Systems, the Chinese PV Group Yingli Solar has recently developed a process suitable for industrial application for the N-type cell. The modules, which Yingli plans to manufacture from the new light collectors starting in autumn 2010, are expected to convert up to 16.5 percent of the light into energy and—with an output of 190 to 315 watts—perform easily as well as the panels offered by western producers.

An alternative could lie in the so-called metallization wrap through cells (MWT).

Here, the power collection tracks required for the interconnection inside the module are moved to the back side of the cells and are connected to the metal contacts on the front through 16 holes drilled into the wafer. This threading of the metallization reduces the creation of shadows. Thus, MWT may be a preliminary step to the backside collectors produced by Sunpower.

It is easier to realize because, in contrast to the Sunpower collectors, the contacts remain on the front. Nevertheless, efficiency can be significantly improved by this “simple” measure. In December 2009, the ECN and the Norwegian PV Group REC achieved an efficiency of 17

36 – Global Solar Technology – July/August 2010

Groundbreaking: Thanks to new solar technologies such as nano-solar-cells, building-integrated PV develops into a major market segment. The central station in Berlin is one of the early, successful projects. (Source: BSW)

percent with modules made of so-called MWT cells of multicrystalline silicon.

This cooperative venture surpassed the efficiency record for MWT cells held by Sandia National Laboratories in the USA by 1.5 percentage points. Even using a standard semiconductor, efficiencies can now be reached that were only possible with expensive high efficiency cells in the past.

No matter which optimization option PV producers use, in the end innovative production methods are the decisive factor when it comes to competitive manufacturing costs. In this connection, the PV sector benefits from the specialized know-how of the companies from the glass industry that have experience with vaporizing, printing, laminating of glass or the development of new specialty glass.

Both business sectors come together for the first time in this manner at glasstec and solarpeq in Düsseldorf—a good basis for higher efficiency in future.

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Industry News

Industry News— continued from page 5 centrotherm photovoltaics concludes successful ramp-up at LG Electronics centrotherm photovoltaics AG concluded the ramp-up of two lines for the manufacturing of crystalline solar cells at its customer LG Electronics. With one line for mono-crystalline and one line for multi-crystalline solar cells, the Korean electronics group is entering the photovoltaic business. “With the first two lines, we have succeeded in entering mass solar cell production within the shortest possible time span,” said Mr. Cho, vice president at LG Electronics. “The aim is to rapidly expand capacity further in order to participate in the sector’s growth, and to develop into one of the leading solar cells suppliers.” LG Electronics is particularly benefiting from the fact that, within the scope of its standardized turnkey lines, centrotherm photovoltaics is also able to adapt process technology to the respective material quality of the wafers utilized by individual customers (silicon substrate for the manufacturing of crystalline solar cells). In this way, the photovoltaic specialists from Blaubeuren are able to optimize production processes, and achieve higher efficiencies and throughput rates.

In the future, centrotherm photovoltaics will manage its customer relationship with LG Electronics from its Korean branch that was established in the autumn of 2009. www.centrotherm-pv.com CRS Reprocessing signs multi-year deal with Bosch CRS Reprocessing Services (CRS) recently signed an exclusive, multi-year contract extension with Bosch Solar Energy, renewing the ongoing relationship between the two companies while increasing CRS’s role in two Bosch locations. The contract runs through 2014 and is eligible for renewal. The terms of the new contract call for CRS to provide service at the Bosch facilities in Arnstadt, Thuringia, Germany, where Bosch manufactures photovoltaic wafers and cells for use in the solar industry. CRS’s solution was customdesigned to meet Bosch’s expansion needs.

In 2011 CRS will be processing more than 1,800 metric tons of slurry each month, and significant additional capacity is in place to support Bosch’s expansion plans.

“Based on our calculations,” said LarsOliver Stock, managing director of Bosch Solar Energy, “Bosch is able to lower our total cost of ownership by having

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CRS handle our reprocessing and their continuous improvement programs are an exceptional value-added proposition for us.” www.crs-reprocessing.com T-Solar deploys BrightView’s InSight-M system BrightView Systems, a provider of in-line metrology based process control and optimization tools for thin film solar cell manufacturing, received technical acceptance and announces deployment of its InSight-M at T-Solar’s thin film solar factory at Ourence, Spain. The tool will be utilized for capturing and analyzing process maps for 100% of the produced panels, a method that will dramatically enhance productivity, drive product improvements enable novel process optimization solutions that improve long term reliability and project bankability. InSight-M will help T-Solar improve the performance of thin-film silicon photovoltaic modules, reduce the production cost per module, and streamline project planning. www.brightview-sys.com, www.tsolar.com Solyndra selects Eyelit’s MES, factory automation, and asset management suite for its new factory Solyndra, Inc., a leading manufacturer of photovoltaic systems, has selected Eyelit’s Manufacturing Software Suite to support PV production at its new automated factory, located in Fremont, California.

Eyelit’s software is successfully deployed in Solyndra’s first factory to track, monitor and provide full visibility throughout the front-end (process) and back-end (assembly) manufacturing processes. Eyelit’s software provides detailed tube-level traceability and is integrated with Solyndra’s Material Control System, to ensure the correct delivery of product to factory tools with the use of automated guided vehicles, conveyors and robots. www.eyelit.com, www.solyndra.com Meyer Burger wins order for over CHF 25 million with a new customer in China Meyer Burger successfully concluded a contract for wire saws and wafer inspection systems worth over CHF 25 million with JA Solar Holdings Co., Ltd. As China’s second biggest manufacturer of solar cells, JA Solar relies on the expansion of its wafer manufacturing facility in Donghai, China, of up to 300 MW in wafering capacity by the end of 2010, on the highly developed slicing- and waferinspection systems from Meyer Burger

Ltd and Hennecke Systems GmbH. The completion of the facility is expected by the end of the year 2010. www.meyerburger.ch WESTPAK Inc. selects ESPEC to develop cutting edge solar simulator A new solar simulator chamber for photovoltaic module testing is currently being developed for WESTPAK, Inc., an independent testing laboratory in San Jose, California. The chamber, manufactured by ESPEC North America, is designed to control the temperature of the solar modules as they are tested for their performance under simulated sun light. WESTPAK has purchased this system in order to help clients assess the performance of their modules at hot or cold temperatures that occur naturally in the field. The new system can simulate winter temperatures as low as -35˚C (-30˚F) and summer temperatures as high as 85˚C (185˚F), extremes, which modules might realistically experience when exposed on a rooftop. To recreate these temperatures, the chamber has a six-foot by nine-foot solar light exposure area, large enough for several PV panels to be tested at a single time, thereby reducing the total testing duration and cost. Six metal halide luminaries will provide simulated solar light exposure, and the chamber will be capable of conducting light simulation as required by the relevant IEC (and similar) module tests. Besides the capacity to operate at different temperatures, the test chamber also features the necessary ability to remove the excess heat generated by its powerful sun simulator lamps. www.westpak.com Oerlikon Leybold Vacuum complements service net in Asia For Oerlikon Leybold Vacuum, being close to customers is an important factor in meeting the increasing demands for faster and more comprehensive after-sales services. Therefore, three new service centers have opened to complement the already existing sales and service network of Leybold Vacuum in Asia. The service center in Hsin Chu, Taiwan, will enhance the performance range with the product lines SCREWLINE and DURADRY, thus offering all the servicing capabilities and options for the full line of fore vacuum, high vacuum and leak detection services, topped with a new decontamination plant.

The newly erected service center in Kulim, Malaysia, opened July 1st. This center will satisfy the locally increasing demand for vacuum technology services,

Global Solar Technology – July/August 2010 – 37

Industry News

especially those from the dynamic markets of photovoltaic production. In Tianjin, China, new after sales services will be offered locally, and the service department will move into a building of its own on the premises of the Tianjin production site as of August this year. In future, the complete product lines of fore vacuum pumps and leak detection will be serviced locally, including the SCREWLINE and DURADRY range of pumps. www.oerlikon.com SOLON Corporation debuts global series of solar proving grounds SOLON Corporation unveiled its state of the art Global Test Site (GTS) Network.

Consisting of three identical outdoor proving grounds located in Tucson, Arizona, San Pietro, Italy, and Berlin, Germany, the GTS Network gives SOLON the unique ability to test and understand regional affects on PV modules and related technologies to optimize module and system design. Regional factors such as temperature, humidity, wind, snow, and dust can significantly affect the performance of solar PV modules. For example, one module type may work well in a warm weather climate like Arizona on a single-axis tracker, whereas, another may perform better in cooler regions, such as Maine, on a fixed-tilt mounting system. At the landmark solar test facilities, SOLON has the ability to study various areas of performance on four platforms: fixed-tilt at 0 degrees, fixed-tilt at latitude, single-axis tracking, and dual-axis tracking. www.SOLON.com 3M joins the Desertec Industrial Initiative 3M has joined the Desertec Industrial Initiative (Dii), based in Germany, as an associate partner. With a diverse portfolio of renewable energy offerings, 3M will contribute in the areas of film, adhesive and coating component technologies to the Desertec initiative. 3M will also contribute its expertise in the area of high-voltage overhead conductors. The company has developed a conductor based on ceramic-fiber reinforced aluminum that can carry twice as much electricity as conventional steel cables, even under the most challenging climatic conditions.

The Desertec Industrial Initiative aims to create the framework generating a sustainable supply of renewable energy climate protective in the deserts of North Africa and the Middle East and to prepare integration with the European power network. The long-term objective is to

satisfy a substantial part of the energy needs of the MENA countries and meet as much as 15% of Europe’s electricity demand. www.3M.com GT Solar announces $70+ million polysilicon equipment contract with a large Asian manufacturer GT Solar International, Inc., has signed contracts with a total value of more than $70 million with a leading Asian polysilicon manufacturer for new CVD equipment and related polysilicon production services. “We are pleased to announce this new order for our polysilicon production equipment to one of Asia’s leading producers,” said Tom Gutierrez, president and chief executive officer of GT Solar. “The polysilicon market is ultimately a commodity market that will eventually be dominated by large, low-cost players. As polysilicon prices continue to decline, our polysilicon reactors, production services and process know-how play a significant role in helping our customers achieve the scale and cost structures they need to remain competitive in a price-sensitive market.” www.gtsolar.com Solar Thin Films, Inc. acquiree BudaSolar Technologies Co., announces US$ 30 million order Solar Thin Films, Inc. announced that its planned subsidiary BudaSolar Technologies Co., Ltd. has signed a contract with Misto Services Co. Ltd. to provide 18MW per year of Tandem Thin Layer Silicon Solar Module Process Line in the Ukraine. The total price to be paid by Misto to Buda is approximately $30,000,000 US. As was announced on April 8, 2010, Solar Thin Films, Inc. is in the final stages of its negotiations to acquire 100% ownership of BudaSolar Technologies Co., Ltd., a Hungarybased technology company that develops thin film solar module manufacturing technologies, including building integrated photovoltaics (BIPV), related equipment, and critical components of turnkey production lines and associated computer software. www.solarthinfilms.com, www.budasolar.hu Ascent Solar commences initial production from its FAB 2 production plant Ascent Solar Technologies, Inc., began initial production of monolithically integrated flexible CIGS modules from its high volume FAB 2 production plant in Thornton, Colorado. “Ascent Solar is the first company to commence regular

38 – Global Solar Technology – July/August 2010

production of monolithically integrated lightweight thin-film CIGS modules using a plastic substrate,” said Farhad Moghadam, president and CEO of Ascent Solar. “This milestone marks the initiation of our regular production capability and our factory ramp up based on market demand. Initial production from FAB 2 is producing 10.5% efficient modules with peak module aperture efficiency as high as 11.9%, which gives Ascent a very competitive product across our target market opportunities.” www.ascentsolar.com First Solar to expand German manufacturing plant First Solar, Inc. announced its intent to expand its German manufacturing plant in Frankfurt an der Oder, doubling local production capacity and creating several hundred new jobs. The company, which already employs more than 600 associates in Frankfurt (Oder) manufacturing First Solar’s trademark thin-film solar modules, is in advanced talks with the German regional and federal authorities to obtain the necessary regulatory permits and financial framework for the expansion.

The expansion would be the first major foreign direct investment in the German green technology sector this year. It would double the annual capacity of the Frankfurt (Oder) manufacturing plant to around 446 megawatts (MW) by the fourth quarter of 2011 from 223 MW today. www.firstsolar.com Circadian Solar named in list of top university spin out businesses in Europe Circadian Solar has been named 16th in a list of the top university spin out businesses, compiled by The Telegraph newspaper. The company’s highlyefficient technology has been developed by top scientists and engineers from the University of Warwick, the semiconductor industry and the automotive industry.

The ranking is based on the company’s YouNoodle Score, which is a quantitative measurement of a startup’s progress and traction based on its traffic, funding, employees and other activity. The score is based on information pulled in from thousands of online sources such as traffic sources, mainstream media and funding sources. Circadian Solar is privately owned, and has received investment from Seven Spires Investments. It employs more than 20 people in the UK, and works with an extended team across Europe. www.circadiansolar.com

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Industry News

LDK Solar succeeds in ramping its 15,000 MT annualized capacity polysilicon production plant LDK Solar Co., Ltd.’s second 5,000 MT train in its 15,000 MT polysilicon plant achieved mechanical completion and will begin ramping production. The first train is now operating at capacity in full closed loop mode and is on track to produce at the annualized capacity of 5,000 MT. “The combined annualized production capacity of 10,000 MT for our first and second trains will provide economies of scale with low power consumption through 48 rod reactors and continue to drive down production cost,” said Xiaofeng Peng, chairman and CEO of LDK Solar. “We look forward to continuing to expand our polysilicon output throughout the year.” www.ldksolar.com Yingli Green Energy Americas expands distribution channel with DC Power Systems partnership Yingli Green Energy Holding Company Limited, which holds the brand Yingli Solar, announced that its U.S. subsidiary, Yingli Green Energy Americas, Inc., has signed a strategic PV module supply agreement with DC Power Systems through the end of 2010. This is one of the largest U.S. agreements for Yingli Green Energy Americas this year and is also the largest contract between the companies to date. Yingli Green Energy Americas’ solar panels have been sold to the residential market through DC Power and other solar distributors. www.yinglisolar.com, www.dcpower-systems.com OPEL International announces management, board of director changes OPEL International Inc. announced changes to its management lineup and its board of directors following the resignation of Robert G. Pico as chief executive officer, president and a member of the board of directors. Leon (Lee) M. Pierhal, president of ODIS Inc., an OPEL Inc. affiliate, has been appointed chief executive officer and president. Lee has been with OPEL since 2001 and is also a member of the board of directors. Lawrence R. Kunkel, who has served several years as a board member and the chair of the Audit Committee, has taken on the position as chairman of the board. Denis Colbourne, the former chairman, remains on the board of directors and continues to serve on the Audit and Compensation Committees of the board. OPEL also expanded Frank Middleton’s role as vice

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president of marketing and chief operating officer of OPEL Solar to include being chief operating officer of all the OPEL companies. www.opelinc.com Most comprehensive database on bureaucracy hampering the installation of PV systems launched The PV Legal consortium launched the largest and most comprehensive online database, gathering detailed quantitative and qualitative data on project development processes and bureaucratic barriers hampering the set-up of photovoltaic (PV) systems in 12 EU countries.

The PV LEGAL project, an initiative co-funded by the Intelligent Energy Europe Programme of the European Commission, has published the result of six months of intense research in 12 EU countries which aimed at providing a thorough research and analysis of all the steps and costs incurred in order to comply with administrative and legal requirements when setting up a PV system in one of these countries. Although most EU countries recognize the potential of solar PV and implement support policies the national PV market is not yet expected to grow to its full potential due to bureaucratic hurdles. In each country, the research has been conducted by surveying the necessary procedures to be complied with for the three main market segments: a) small-scale installations on residential buildings; b) small to medium-scale installations on commercial buildings and c) medium to large-scale ground-mounted installations on open lands. For each segment the project development processes have been identified and described in detail with information on duration, waiting time and legal-administrative costs of each process. www.pvlegal.eu John Garofalo joins Premier Power as vice president of business development Premier Power Renewable Energy announced that John Garofalo has joined the executive management team as its vice president of business development.

Prior to joining Premier Power, Mr. Garofalo served as vice president of strategy and business development at CED International (Consolidated Energy Design), where he assisted the energyconsulting firm through several transitions and acquisitions including training and mentoring the sales and business development teams toward a unified message and strategy. Prior to that, he

served as VP of business development with National Grid Energy Services. www.premierpower.com

Fraunhofer-Gesellschaft awards science prize to solar researchers in Freiburg Dr. Andreas Bett and Dr. Frank Dimroth of the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg develop solutions to make the conversion from sunlight to electricity cheaper and more efficient for the future. To this end, they and their team have been working for over ten years on solar modules that concentrate solar radiation by a factor of 500 onto tiny solar cells. This procedure reduces the area of the semiconductor material required and enables the use of novel, extremely efficient solar cells. The researchers in Freiburg received huge recognition last year for their development of a metamorphic triple-junction solar cell that achieved a record efficiency of 41.1%.

Together with a concentrating optic, the highly efficient multi-junction solar cells were implemented in now market-ready concentrator modules. In recognition of these achievements, Dr. Andreas Bett and Dr. Frank Dimroth received the highest distinction of the Fraunhofer Gesellschaft, the 2010 Joseph von Fraunhofer Prize. www.ise.fraunhofer.de Trina Solar enters strategic partnership with TUV Rheinland, UL and CGC Trina Solar Limited announced through its subsidiary, Changzhou Trina Solar Energy Co. Ltd., that it has signed a strategic partnership agreement with TUV Rheinland Group, Underwriters Laboratories Inc. and China General Certification Centre. Trina Solar entered into a Testing at Manufacturers Premises Scheme with TUV Rheinland and a Witness Test Data Program with UL to perform product certification tests within the company’s Changzhou PV Testing Centre whereby in accordance with IEC 17025, processes performed are witnessed by respective certification body engineers. trinasolar.com, tuv.com, ul.com, cgc.org.cn

Global Solar Technology – July/August 2010 – 39

Title Events Calendar

Events Calendar 2-5 September 2010 Soltec Hameln, Germany www.rainer-timpe.de

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

22-24 February 2011 SNEC PV Power Expo 2011 Shanghai, China www.snec.org.cn

12-14 October 2010 Solar Power 2010 Los Angeles, California, USA www.solarelectricpower.org

16-18 February 2011 EXPO Solar Gyeonggi, South Korea www.exposolar.org

3-5 April 2011 PV America Philadelphia Philadelphia, Pennsylvania, USA www.pvamericaexpo.com

26-28 October 2010 PV Taiwan 2010 Taipei, Taiwan www.pvtaiwan.com 27-29 October 2010 DIREC 2010 Delhi, India www.exhibitionsindiagroup.com 17-19 November 2010 PVTech Milan, Italy www.hitechexpo.eu

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