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Public Release of Optimization of Metallization Scheme for Thin Emitter Wrap-through Solar Cells for Higher Efficiency, Reduced Precious Metal Costs, and Reduced Stress.

DE2008940520

Publication Date	2008
Personal Author	Ruby, D. S.; Murphy, S.; Meakin, D.; Dominguez, J.; Hacke, P.
Page Count	46
Abstract	Back-contact crystalline-silicon photovoltaic solar cells and modules offer a number of advantages, including the elimination of grid shadowing losses, reduced cost through use of thinner silicon substrates, simpler module assembly, and improved aesthetics. While the existing edge tab method for interconnecting and stringing edge-connected back contact cells is acceptably straightforward and reliable, there are further gains to be exploited when you have both contact polarities on one side of the cell. In this work, we produce 'busbarless' emitter wrap-through solar cells that use 41% of the gridline silver (Ag) metallization mass compared to the edge tab design. Further, series resistance power losses are reduced by extraction of current from more places on the cell rear, leading to a fill factor improvement of about 6% (relative) on the module level. Series resistance and current-generation losses associated with large rear bondpads and busbars are eliminated. Use of thin silicon (Si) wafers is enabled because of the reduced Ag metallization mass and by interconnection with conductive adhesives leading to reduced bow. The busbarless cell design interconnected with conductive adhesives passes typical International Electrotechnical Commission damp heat and thermal cycling test.
Keywords	Solar cells Optimization Adhesives Aesthetics Design Efficiency Fill factors Metals Power losses Silicon solar cells Silver Substrates Thermal cycling
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Sandia National Labs., Albuquerque, NM.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200910
Contract Number	DE-AC04-94AL85000

Public Release of Optimization of Metallization Scheme for Thin Emitter Wrap-through Solar Cells for Higher Efficiency, Reduced Precious Metal Costs, and Reduced Stress.

Public Release of Optimization of Metallization Scheme for Thin Emitter Wrap-through Solar Cells for Higher Efficiency, Reduced Precious Metal Costs, and Reduced Stress.
DE2008940520

Publication Date	2008
Personal Author	Ruby, D. S.; Murphy, S.; Meakin, D.; Dominguez, J.; Hacke, P.
Page Count	46
Abstract	Back-contact crystalline-silicon photovoltaic solar cells and modules offer a number of advantages, including the elimination of grid shadowing losses, reduced cost through use of thinner silicon substrates, simpler module assembly, and improved aesthetics. While the existing edge tab method for interconnecting and stringing edge-connected back contact cells is acceptably straightforward and reliable, there are further gains to be exploited when you have both contact polarities on one side of the cell. In this work, we produce 'busbarless' emitter wrap-through solar cells that use 41% of the gridline silver (Ag) metallization mass compared to the edge tab design. Further, series resistance power losses are reduced by extraction of current from more places on the cell rear, leading to a fill factor improvement of about 6% (relative) on the module level. Series resistance and current-generation losses associated with large rear bondpads and busbars are eliminated. Use of thin silicon (Si) wafers is enabled because of the reduced Ag metallization mass and by interconnection with conductive adhesives leading to reduced bow. The busbarless cell design interconnected with conductive adhesives passes typical International Electrotechnical Commission damp heat and thermal cycling test.
Keywords	Solar cells Optimization Adhesives Aesthetics Design Efficiency Fill factors Metals Power losses Silicon solar cells Silver Substrates Thermal cycling
Source Agency	Technical Information Center Oak Ridge Tennessee
Corporate Authors	Sandia National Labs., Albuquerque, NM.; Department of Energy, Washington, DC.
Supplemental Notes	Sponsored by Department of Energy, Washington, DC.
Document Type	Technical Report
NTIS Issue Number	200910
Contract Number	DE-AC04-94AL85000