Optical Materials by Sol-Gel Method Tunable Laser samples
prepared by the sol-gel method Owing to the original efforts of
the National Aeronautics and Space Administration to supply
electric current from silicon photovoltaic (PV) cells to space
vehicle, such devices are now available at a price of several US
dollars per watt of power. At present large scale solar cell
arrays are operating in inaccessible locations distant from
conventional electricity plants. Previous estimates of price
decrease to $1-$2/W which were obtained by making comparisons
with the aluminium or electronic computers industry, may be
slightly optimistic as the difficulties of preparing inexpensive
silicon with a high photoelectric yield can not be removed by
increased production. One way of lowering the price of PV
electricity is to concentrate the solar radiation, particularly
that part which is most efficient in PV energy conversion, on
high efficiency solar cells. Although expensive their amount and
cost can be considerably diminishe