Industrial implementation of epitaxial solar cells over low-grade silicon substrates

Many efforts are being dedicated to the search of alternative substrates for solar cells, due to the shortage of silicon feedstock that the photovoltaic industry is currently facing. One possible solution for this problem is to use low-cost silicon substrates, as for instance metallurgical silicon, for which there are no supply issues, taking these substrates as a holder of a high quality epitaxially grown silicon layer where solar cell can be built. An industrial solar cell process for this new type of structures has been developed at IMEC and implemented with factory equipments at the facilities of Isofoton. The main difference with respect to a standard cell process is the need to reach a good light confinement into the epitaxial layer to maximize cell output power by the increase of photon absorption in the high quality silicon layer. Efficiencies of over 9 % have been achieved in an industrial environment. From laboratory scale results an increase in industrial cell efficiency up to 12% is foreseen