Boston-based Bandgap Engineering Inc. says it has increased the average efficiency of standard, commercial solar cells by 0.4% by replacing the standard surface texture with its nanowire technology on the same production line.
Bandgap's report comes as the result of a demonstration it conducted with a cell manufacturer. The manufacturer ran 84 multicrystalline wafers through its standard industrial cell process – a standard emitter, standard silicon-nitride and standard screen printing with full back-side Al metal, on standard full-area 156 mm x 156 mm wafers – with half the wafers in the batch using its nanotexture and the other wafers using standard acidic texture.
‘The best nanowire solar cell had 17.76% efficiency, compared to 17.32% for the best standard solar cell,’ says Jeff Miller, Bandgap's senior device scientist. ‘Since the cell process was optimized for the standard cells, and not for nanowire cells, and since we have a clear path to further improve our technology, I expect further efficiency improvements with a fairly straightforward optimization.’
Bandgap is positioning its nanowire technology as a drop-in upgrade for crystalline silicon manufacturers using standard processing technologies. In particular, as the technology gives low reflection for all grain orientations, Bandgap says the upgrade is particularly suited for multicrystalline wafers, which have higher reflection.