43 research outputs found
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Role of Polycrystalline Thin-Film PV Technologies in Competitive PV Module Markets: Preprint
This paper discusses the developments in thin-film PV technologies and provides an outlook on future commercial module efficiencies achievable based on today's knowledge about champion cell performance
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Thin Film CIGS and CdTe Photovoltaic Technologies: Commercialization, Critical Issues, and Applications; Preprint
We report here on the major commercialization aspects of thin-film photovoltaic (PV) technologies based on CIGS and CdTe (a-Si and thin-Si are also reported for completeness on the status of thin-film PV). Worldwide silicon (Si) based PV technologies continues to dominate at more than 94% of the market share, with the share of thin-film PV at less than 6%. However, the market share for thin-film PV in the United States continues to grow rapidly over the past several years and in CY 2006, they had a substantial contribution of about 44%, compared to less than 10% in CY 2003. In CY 2007, thin-film PV market share is expected to surpass that of Si technology in the United States. Worldwide estimated projections for CY 2010 are that thin-film PV production capacity will be more than 3700 MW. A 40-MW thin-film CdTe solar field is currently being installed in Saxony, Germany, and will be completed in early CY 2009. The total project cost is Euro 130 million, which equates to an installed PV system price of Euro 3.25/-watt averaged over the entire solar project. This is the lowest price for any installed PV system in the world today. Critical research, development, and technology issues for thin-film CIGS and CdTe are also elucidated in this paper
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Polycrystalline Thin Film Photovoltaics: From the Laboratory to Solar Fields; Preprint
We review the status of commercial polycrystalline thin-film solar cells and photovoltaic (PV) modules, including current and projected commercialization activities
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Solar America Initiative (SAI) PV Technology Incubator Program: Preprint
The SAI PV Technology Incubator Program is designed to accelerate technologies/prodesses that have successfully demonstrated a proof-of-concept/process in a laboratory
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Performance Test of Amorphous Silicon Modules in Different Climates - Year Four: Progress in Understanding Exposure History Stabilization Effects; Preprint
The four-year experiment involved three identical sets of thin-film a-Si modules from various manufacturers deployed outdoors simultaneously in three sites with distinct climates. Each PV module set spent a one-year period at each site before a final period at the original site where it was first deployed
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Material Requirements for Buffer Layers Used to Obtain Solar Cells with High Open Circuit Voltages
This paper discusses material requirements for junction layers needed to obtain solar cells with highest possible open-circuit voltages (VOC). In a typical a-Si:H-based ''p/i/n'' solar cell, this includes the transparent conductive oxide (TCO) contact layer, the p-layer, a ''buffer layer'' inserted at the p/i interface, and the surface portion of the intrinsic layer. In HIT-cells, the i-layer between (n-type) c-Si and (p-type) a-Si:H may be regarded as the buffer. Our suggestion to obtain high values of VOC relies on using materials with high lifetimes and low carrier mobilities that are capable of reducing surface or junction recombination by reducing the flow of carriers into this loss-pathway. We provide a general calculation that supports these approaches and can explain why these schemes are beneficial for all solar cells
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Why is the open-circuit voltage of crystalline Si solar cells so critically dependent on emitter- and base-doping?
This paper discusses the critical dependence of the open-circuit voltage (VOC) of crystalline Si solar cells on the emitter and base doping levels. Contrary to conventional models that try to ascribe VOC-limitations to (independent) bulk and surface recombination losses, the authors suggest, as the dominant mechanism, the formation of a compensated ``buffer layer'' that is formed as phosphorus is diffused into the p-type (boron-doped) base. The only purpose of the base doping is to optimize the buffer layer. Their calculations show that this model makes the achievement of high VOC and good carrier collection (JSC, FF) interdependent. Sanyo's ``HIT'' solar cells are an example of a different method to implement this buffer layer concept for crystalline Si solar cells. The general principle for a VOC-enhancing buffer layer relies on using materials with high lifetimes and low carrier mobilities that are capable of reducing surface or junction recombination by reducing the flow of carriers into this loss-pathway
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Perspective on photovoltaic amorphous silicon
Amorphous silicon is a thin film option that has the potential for a cost-effective product for large-scale utility photovoltaics application. The initial efficiencies for single-junction and multijunction amorphous silicon cells and modules have increased significantly over the past 10 years. The emphasis of research and development has changed to stabilized efficiency, especially that of multijunction modules. NREL has measured 6.3%--7.2% stabilized amorphous silicon module efficiencies for US products, and 8.1% stable efficiencies have been reported by Fuji Electric. This represents a significant increase over the stabilized efficiencies of modules manufactured only a few years ago. An increasing portion of the amorphous silicon US government funding is now for manufacturing technology development to reduce cost. The funding for amorphous silicon for photovoltaics by Japan over the last 5 years has been about 50% greater than that in the United State, and by Germany in the last 2--3 years more than twice that of the US Amorphous silicon is the only thin-film technology that is selling large-area commercial modules. The cost for amorphous silicon modules is now in the 1.00--1.50/W{sub p} for plants with 10 MW/year capacities. 10 refs
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Model for Staebler-Wronski degradation deduced from long-term, controlled light-soaking experiments
Long-term light-soaking experiments of amorphous silicon photovoltaic modules have now established that stabilization of the degradation occurs at levels that depend significantly on the operating conditions, as well as on the operating history of the modules. The authors suggest that stabilization occurs because of the introduction of degradation mechanisms with different time constants and annealing activation energies, depending on the exposure conditions. Stabilization will occur once a sufficient accumulation of different degradation mechanisms occurs. They find that operating module temperature during light-soaking is the most important parameter for determining stabilized performance. Next in importance is the exposure history of the device. The precise value of the light intensity seems least important in determining the stabilized efficiency, as long as its level is a significant fraction of 1-sun