[net.space] PV Cell efficiency

Kevin.Dowling%CMU-RI-ROVER@sri-unix.UUCP (11/10/83)

Reported in latest Laser Focus and EOSD:
	Spire Corp. has developed a process for growing a thin film of
Ga-As directly on a silicon substrate. The process converts a conventional
single band-gap Si cell with a typical efficiency of 12% to a two band-gap
cell with a theoretical efficiency of 30% and a likelyconversion rate
of 25% in large scale production. In solar cell application, Si is lower
in cost but GaAs is more efficient because it captures a larger portion
of the solar spectrum. The blurb (in the postdeadline reports section)
goes on to mention that the method is a metalorganic chemical vapor
process that allow extremely precise deposition of the GaAs.
At a production level of 1MW per year, this photovoltaic process is estimated
to add $1.30/W to cell costs; at 50MW/year, only $0.22/W. Cell effficiency
will thus be more than doubled.