Presented at: 26th EU PVSEC European Photovoltaic Solar Energy Conference and Exhibition, Hamburg, Germany, , 5-9 september 2011.
Silicon hetero-junction solar cell technology has the potential to combine high efficiencies with thin wafers. Cell efficiencies of 21 % can be achieved on 170 micron thick wafers. A significant reduction of the cost-performance ratio can be realized if these fragile cells are integrated reliably in solar modules. This requires low stress and low-temperature interconnection of individual cells. Also, hetero-junction cells are known to be susceptible to moisture ingress inside the module. Single cell modules have been manufactured using conductive adhesive as interconnection and using a moisture blocking back sheet to protect the cells. The modules have been exposed to climate chamber tests (damp-heat and thermal cycling) according to the IEC 61215 ed. 2 standard. Infrared analysis (IR) and electroluminescence (EL) images were taken to investigate the integrity of cells and their interconnections. Modules made with moisture blocking back-sheets showed that the modules did survive 1500 hours (1.5 times IEC) of damp heat and over 340 thermal cycles with less than 5% reduction in power output. The industrial feasibility of this module technology was demonstrated by manufacturing 72-cell modules, using cells obtained from an industrial party. Assembly of the modules was done using a tabber-stringer capable to work with conductive adhesives, designed for low temperature interconnection.
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