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Title:
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Influence of wafer thickness on the performance of multicrystalline Si solar cells : an experimental study
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Author(s):
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Published by:
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Publication date:
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ECN
Solar Energy
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1-10-2001
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ECN report number:
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Document type:
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ECN-RX--01-041
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Article (scientific)
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Number of pages:
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18
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Published in: Progress in Photovoltaics: Research and Applications (John Wiley & Sons Ltd.), , 2002, Vol.10, p.279-291.
Abstract:
The influence of the thickness of silicon solar cells has been investigated using neighbouring multicrystalline silicon wafers with thickness ranging from 150 to 325 µm. For silicon solar cell structures with a high minority carrier diffusion length one expects that Jsc would decrease as the wafer becomes thinner due to a shorter optical path length. It was found experimentally that Jsc is nearly independent of the thickness of the solar cell, even when the minority carrier diffusion length is about 300 µm. This indicates that the Al rear metallisation acts as a good back surface reflector. A decrease in Jsc is observed only if the wafer thickness becomes less than about 200 µm.The observed trend in Voc as a function of the wafer thickness has been explained with PC1D modelling by a minority carrier diffusion length in the Al-doped BSF which is small in relation to the thickness of the BSF. This effectively increases the recombination velocity at the rear of the cell.
We have shown that the efficiency of solar cells made with standard industrial processing is hardly reduced by reducing the wafer thickness. Solar cell efficiencies might be increased by better rear surface passivation.
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