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Photovoltaics Users Group- Announcements
NCCAVS Joint User Group Meeting
Topic: Technology for Clean Energy
Meeting Date: February 22, 2012
Time: 9am - 6pm
Session I (Morning):
| Session I Chairs: |
Sing-Pin Tay, Mattson Technology
Susan Felch, SVTC
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9:00 - 9:05 Opening Remarks
9:05 - 9:45 The Journey of SunPower to 20% Module Efficiency (Invited)
- Gabriela Bunea and Doug Kim, SunPower Corporation
Abstract: In 2007, SunPower introduced its Gen2 Maxeon all-back-contact cell technology, achieving median production cell efficiencies of 22.2% to 22.4%. Based on SunPower's cell format and module design at that time, the resulting flashed module power under standard test conditions (STC) was 305 watts, corresponding to a module efficiency of 18.7%. SunPower has steadily improved the absolute module efficiency through a combination of cell and module design improvements. Between 2007 and 2011, such changes have enabled a 1.4% absolute reduction in cell to module conversion efficiency loss, increasing module power by 7% and enabling the volume production of the world-record-holding 20% efficient module. The changes are designed to increase light capture in the cell and minimize cell to module conversion losses. They include a switch to a higher area cell, adoption of anti-reflective coated (ARC) glass and the use of advanced module materials that improve the power performance of the encapsulated solar cell. This paper also reports on high volume manufacturing of the industry's first commercially available 20% efficiency Si modules. SunPower has produced over 150MW of 20% efficiency modules since its introduction in 2011. The ability to manufacture 20% efficient modules on a large commercial scale is an important milestone for the PV industry. Of equal importance, the reliability/durability of these high efficiency modules, representing a lifetime significantly longer than 25 year, needs to be confirmed. The present study summarizes years of thorough reliability studies and utilizes both accelerated aging and real-world field conditions to validate the PV modules robust resistance to humidity, temperature, UV, and high voltage. The experimental results and modeling studies demonstrate that ultra high efficiency c-Si PV modules with excellent reliability/durability can be produced on a large commercial scale by optimized module and cell technology.
Biography: Sung Dug "Doug" Kim is a Principal Engineer at SunPower Corporation since 2010. He is responsible for the High Efficiency c-Si Solar module technology. Prior to joining SunPower he was a Senior Scientist at GE Plastics from 2002 to 2010. From 1991 to 1995 he held the position of Research Scientist at the Polymer Research Institute of LG Chemical Ltd., Korea. Doug received his Ph.D. degree in Polymer Science and Engineering from Lehigh University, Bethlehem, USA, in 2000. He obtained a M.S. degree in Biological Science and Engineering from Korea Advanced Institute of Science and Technology (KAIST), Korea, in 1991, and a B.A. degree in Physics from Seoul National University, Seoul, Korea, in 1989. Doug was a Postdoctoral Fellow in the Department of Chemical Engineering, Northwestern University, USA, in 2002. He holds 7 US patents, has filed 16 US patent applications, and has authored more than 15 technical publications on polymer.
9:45 - 10:05 Characterization of Solar Grade Silicon Contaminants
- Gary Mount, Larry Wang, Karol Putyera, and Matt Lepage, Evans Analytical Group
Abstract: The term 'Solar Grade Silicon (SoG)' has been used for many years but until recently, there were no specifications as to what this actually meant. Without specifications, suppliers of silicon have been using 'number of nines' purity as one way to differentiate their product. However you can make the number of 'N's just about anything you want by choosing which elements to include and exclude in the purity measurement. More importantly 'number of nines' does not differentiate between elements that are important for solar performance and those that are not. The SEMI organization has just released specifications for virgin silicon feedstock material (Solar Grade Silicon) defining 4 grades [SEMI PV17-0611]. The specifications define upper limits of impurities for various elements, grouped by their function and importance on PV performance. There is no discussion of 'nines'. The SEMI organization has also just released specifications for silicon wafers for use in photovoltaics [SEMI PV22-1011]. There is recognition that oxygen, carbon and iron content are important in the wafers. There is also recognition that total metal content may be important. In this work we look at various methods for contaminant analysis including SIMS, ICP-MS, GDMS and NAA, reporting on strengths and limitations of each. Bulk sampling methods and profiling methods are discussed.
Biography: Not yet available
10:05 - 10:25 Network Break
Session II:
| Session II Chairs: |
Kapila Wijekoon, Applied Materials
David Hansen, Hitachi Global Storage Technologies
Huey-Chiang Liou, SunPower Corporation
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10:25 - 11:05 Solar Technology - Crystalline Silicon PV Solar Cells (Invited)
- David Tanner, Applied Materials
Abstract: The growth of terrestrial solar over the last 10 years has been remarkable. This has been attributed mainly to the growth of c-Si technologies worldwide. This presentation offers a discussion of the process value chain of c-Si technologies, details the remarkable growth of the industry driven by module and balance of systems (BOS) cost reductions. Last, Applied Materials' technology roadmap presents opportunities for continued industry growth, module efficiency improvements, and further cost reduction.
Biography: David Tanner is the global crystalline silicon (c-Si) process director for Applied Solar Group at Applied Materials, Inc.
An industry veteran with more than three decades of experience, his background encompasses engineering, development and manufacturing for a number of solar technologies such as thin film (TF) silicon, crystalline silicon and gallium arsenide / gallium indium phosphide tandems for space and terrestrial applications. Mr. Tanner holds a MS degree in Applied Physics, 36 patents and has published more than 43 papers on solar-related subjects.
11:05 - 11:25 Floating Thin Film c-Si for Solar Cells
- Uri Cohen, UC Consulting
Abstract: A new Float Foil Growth (FFG) technique has been demonstrated for growing thin crystalline Si foils from molten metal solvent, such as molten indium (In) or tin (Sn), at temperatures below 1,000 degrees C. Si-source is first dissolved to saturation (or close to saturation) in a molten metallic bath (or solvent) at a temperature T2 (T2 ≤ 1,000 degrees C), and the molten bath is then cooled to T1, where T2 » T1. Due to lower solubility of Si at T1 than at T2, Si separates (or is driven) out of solution and, due to its much lower density than that of the molten metallic bath, it floats to the top of the bath to form a floating thin c-Si foil. The thickness of the c-Si foil is determined primarily by T2, the dissolution temperature (i.e., Si solubility at T2), and the depth of the molten bath. We report here preliminary results demonstrating the utility of the FFG technique for growing high purity free standing c-Si foils. In preliminary experiments, flat thin c-Si foils, with thickness range between 50-200μm, were obtained from molten indium (In) baths. The Si foils were mono and quasi-monocrystalline with crystalline (or grain) size of several millimeters, having a strong <111> orientation. The c-Si foils were very pure; with In (solvent) content as low as 14 ppb. Other metallic impurities were below 0.1 ppm, oxygen content was as low as 1.8 ppm, and carbon content was below the detection level (50 ppb). Due to lack of interfacial stresses (between the floating Si foil and the molten bath) during growth, the c-Si foil can grow with essentially no dislocations. When produced on large scale, it is anticipated that a single line would be capable of producing about 10-50 square meters of c-Si foil per hour. Also, due to extremely small segregation coefficients of most impurities, the FFG process is self purifying. It is expected that low grade Si-source (such as metallurgical Si) could be used in FFG c-Si foil growth, thereby further reducing the cost of c-Si foil material for photovoltaic applications. It is further expected that large FFG thin c-Si foils, when produced on large scale, will offer Si material cost and energy savings well beyond 80%, compared with conventional sliced Si wafers, with similar photovoltaic conversion efficiency.
Biography: Dr. Uri Cohen received B.Sc. and M.Sc. degrees in Chemistry and Physical Chemistry, respectively, from the Hebrew University in Jerusalem, Israel, and a Ph.D. degree in Materials Science & Engineering from Stanford University in 1978. After receiving his Ph.D. degree, Dr. Cohen worked at Bell Laboratories in Murray Hill, NJ, where he developed an electroplating process of Ag-Pd alloy for contact plating, and Cyclic Multilayered Alloy (CMA) plating. He later worked at the Technion, Haifa, Israel, before he joined Sperry Univac in Santa Clara, CA, to work on the design and processing of Thin Film Heads (TFHs) for disk drives. He was in charge of plating Ni-Fe, Au, Ni, and Cu in the TFH wafer fabrication. In 1986 he became a consultant to several vendors of thin film heads. Dr. Cohen has been the founder of four start-up companies: Silver Memories, ToroHead, Jets Technology and Ribbon Technology. Dr. Cohen has authored or co-authored about 53 technical publications, and he owns about 60 (domestic and foreign) issued and pending patents, which he has invented or co-invented.
11:25 - 12:05 Correlation of Cell Efficiency and Photo-luminance Image (Invited)
- Bruce True, Intevac
Abstract: Photoluminescence imaging is a technique for assessing the quality of silicon photovoltaic devices at any point during the production process, from cast ingot to finished cell. Photoluminescence intensity is related to the minority carrier lifetime and doping level of the silicon. The NanoVista PL Inspection system is a previously described inspection system for rapidly acquiring photoluminescence images of silicon photovoltaic material 1.
A detailed inspection of the photoluminescence image of an as-cut multi-crystalline silicon wafer will reveal the quality of the wafer. In this presentation I describe a set of automated image analysis metrics that can be used to predict the finished cell efficiency based on the photoluminescence image. Three key features of the wafer are extracted from the PL image: regions of high concentrations of metal impurities, the degree of crystallinity of the wafer, and the size and location of crystal dislocations in the wafer. Using a training set of wafers for which the finished cell efficiency is known, a model is generated that can correlate the finished cell efficiency with the photoluminescence image of the unprocessed, as-cut wafer. The accuracy of the correlation is assessed using the standard metrics of coefficient of determination and the mean absolute error of the prediction.
1 K. Janakiraman, B. True, Proceedings of the 25th EPVSEC, Valencia, Spain (2010).
Biography: Dr. Bruce True joined Intevac in 2004. He has extensive technical qualifications in imaging and spectroscopy applications and also technical development of low light cameras. He has developed research-oriented products based on CCD, CID, and CMOS sensors and utilizing image intensifiers. He has provided technical support to research institutions such as NASA and LBNL. Dr. True received his Ph.D. in Chemistry from the University of Arizona and his B.A. degree in Chemistry from the University of Texas at Austin.
12:05 - 1:30 Lunch Break
Session III (Afternoon):
| Session III Chairs: |
Michael Current, Current Scientific
Jeffery Shields, Adesto Technologies
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1:30 - 2:10 A Bright Future of HB-LED Manufacturing (Invited)
- Tom Morrow, SEMI
Abstract: The high-brightness light emitting diode (HB-LED) industry has become a major segment as manufacturing capacity and equipment spending have more than tripled since 2009 to meet the demand for LED TV backlighting. The future of the HB-LED industry, however, will depend upon the growth of LED-enabled solid state lighting. Projections for the long-term increase in LED demand from general illumination applications depend on major cost reductions - perhaps as much as 20X improvement in $/klm at the packaged LED level. That's only going to be possible by moving to larger size wafers and scaling to automated high volume production with tightly controlled processes for high yields. Experience in the semiconductor and other industries show that industry-wide manufacturing standards are essential for high quality, high volume microelectronics production. This presentation will provide an overview of the current state of HB-LED manufacturing and review the objectives and status of industry-wide manufacturing standards.
Biography: Tom Morrow is Executive Vice President of SEMI, responsible for Emerging Markets such as LEDs, OLEDs, MEMS and printed and organic electronics. Prior to joining SEMI in 2006, Tom was senior vice president at e21, a full service marketing consultancy whose clients included Intel, IBM, TSMC, Texas Instruments and other high technology leaders. Tom also helped found memory products company Lexar Media, purchased by Micron in 2006. He has also held executive positions at Motorola, serving as Director Marketing for Asia, and Omron Electronics, holding the position of Assistant Division Manager for Factory Automation.
2:10 - 2:30 Advances in Lithium Ion Capacitor Technology
- James Banas, JM Energy, JSR Micro, Inc.
Abstract: Lithium Ion Capacitor (LIC) energy storage devices offer unique performance advantages over Lithium ion batteries and conventional supercapacitors. Unlike Lithium ion batteries, LIC provides a long cycle life and is suitable for high power applications. In comparison to conventional supercapacitors, LIC provides a greater energy density and very high charge retention. JM Energy continues to advance Lithium Ion Capacitor (LIC) technology with a second generation of Ultra Low Resistance (ULR) cells. The ULR cells provide a 70% reduction in internal resistance, which leads to greater efficiency and lower energy loss during charge/discharge cycling. Changes in electrolyte composition have significantly improved cold temperature performance, and capacitance at -30 degrees C is 50% improved over generation one cells. In tandem with traditional laminated capacitors, JM Energy has incorporated ULR technology in the development of a new flat prismatic can type structure. Because of the larger surface area as compared to a conventional cylindrical cell design, the prismatic cell has higher heat radiation efficiency and can therefore suppress degradation due to heat generated during charging and discharging. The prismatic form factor offers a 20-30% improvement in packaging efficiency over cylindrical cells since there is less wasted space between cells. The improved ULR laminated and new ULR prismatic lithium ion capacitors offer improved energy and packaging efficiencies as well as enhanced cold temperature performance needed for emerging applications for hybrid electric vehicles, more efficient aircraft, life sciences diagnostic equipment, and stable backup power.
Biography: Jim Banas: Has over 20 years of experience in the semiconductor industry as a photolithography engineer. After joining JSR Micro Inc in 1999, Jim continued his work in the photolithography area. In 2008, Jim joined JSR's newly formed Environmental Energy division and has since been involved with the sales, applications and marketing of Lithium Ion Capacitors, aqueous based binders for batteries and fuel cell membranes. He holds a BA in Chemistry from the SUNY College at Buffalo.
2:30 - 2:50 Network Break
Session IV:
| Session IV Chairs: |
Maria Peterson, JSR Micro
Kavita Murthi, Matheson-Trigas
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2:50 - 3:30 A Flow Battery for Grid Storage: H2/Br2 - performance and cost issues (Invited)
- Vincent Battaglia, Lawrence Berkeley National Laboratory
Abstract: As California alters the balance of its energy portfolio towards more carbonless, renewable energy sources, it is strongly anticipated that these renewables will of the intermittent variety, such as the energy generated by the sun through heat and photons (i.e., wind and solar). At low fractions of the total energy portfolio, these sources are manageable via the present carbon-based infrastructure; however, such management has the negative consequence of diminishing the impact on carbon emissions for which they were enlisted in the first place. However, as the fraction of intermittent renewables increases, and the seriousness of reducing carbon emissions mutually increases, these intermittent sources will need to be managed in a more efficient, carbonless, and cost effective manner. Many means exist for leveling intermittents, including pumped-hydro, compressed air, and fly wheels. Each has its own advantages and unique drawbacks; the drawbacks include limited siting or performance characteristics. Another means of leveling the energy is through batteries, although batteries can be expensive. A possible solution to the battery cost issue is a flow battery. A flow battery differs from a traditional battery in that the energy and power are separated. More specifically, an order of magnitude of energy density is typically sacrificed for two orders of magnitude increase in power density. Depending on the application and the cost of the power unit and the chemicals involved in providing the energy, such a battery can be cost effective. In this presentation, we will go through the progress made on a H2/Br2 battery funded by ARPA-E and identify some of the major performance and cost barriers, which are consistent across similar flow systems.
Biography: Vince Battaglia has degrees in chemical engineering from The Johns Hopkins University, B.S.; and The University of California at Berkeley, M.S. and Ph.D. Upon graduating he spent 11 years with Argonne National Laboratory's Battery group, with 4 1/2 of those years spent in Illinois studying LiAl/FeS2 and Li/VOx rechargeable batteries for EV applications and the other 6 1/2 years on assignment in Washington DC as a technical advisor to the Electrochemical Energy Storage Program of the Office of Vehicle Technologies of Energy Efficiency and Renewable Energy of the U.S.D.O.E. He has spent the last eight years at Lawrence Berkeley National Laboratory where he leads a research group studying the energy, power, and cycling limits of advanced battery materials designed for hybrid and electric vehicles. He has been recognized by the DOE for his technical contributions to their efforts with the 2011 DOE Vehicle Technologies Program &D Award and recognized by his peers as an expert in cell analysis and failure modes. Vince also participates on the USABC Technical Advisory Committee where he provides, on a quarterly basis, technical expertise on the evaluation of battery developer programs sponsored by DOE. He has authored over 35 scientific publications and has 1 patent.
3:30 - 3:50 User Program at the Molecular Foundry (LBNL) for Industrial Applications: Metrics for Success
- David Bunzow, The Molecular Foundry, LBNL
Abstract: The Molecular Foundry at Lawrence Berkeley Nation Laboratory is a Department of Energy-funded program providing support to researchers from around the world whose work can benefit from or contribute to nanoscience. Through unparalleled access to state-of-the-art instruments, materials, technical expertise and training, the Foundry provides researchers with the tools to enhance the development and understanding of the synthesis, characterization and theory of nanoscale materials. The User Program within the Molecular Foundry offers a prospective user team access to these world class equipment and instruments, as well as close collaboration with our senior scientific staff to perform investigations outlined in your peer-reviewed user proposals. The Foundry supports these unique amenities in a variety of ways, including low cost of access and use, favorable IP rights and enhanced ways to continue your research area investigation once initial work has been completed. Funding for the Molecular Foundry is provided by the US DOE. This talk will provide details of how our User Program operates and what is needed for your organization to collaborate with us and become a new Foundry user. Through description of program elements, relevant statistics and case studies that support our exceptional history of industrial projects success, this presentation will guide you through our complete process - from proposal submission through the steps to getting your work published in applicable scientific journals. It will explain multiple variations of working relationships the Molecular Foundry offers, such as proprietary vs. non-proprietary work, as well as accelerated timeline options such rapid access, instrument only and sample only options.
Biography: Not yet available
3:50 - 5:00 Networking
5:00 - 6:00 Exhibition Reception
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