Nanosolar is the first and so far only company in the world that has managed to make efficient solar cells work on a metal foil substrate that is both low cost and highly conductive. Our metal foil has a conductivity that is more than 20 times higher than that of the stainless steel used by others -- and thus enables major cost reduction on the solar cell's thin-film bottom electrode.

Note that a thin-film solar cell consists most fundamentally of an absorber layer (the semiconductor) sandwiched in between a top and a bottom electrode layer. If the thin films of a solar cell are deposited directly onto a highly conductive metal foil (as opposed to glass or stainless steel), then the bottom electrode gets much simpler because the substrate can do the job of carrying the current.