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of silicon, a very abundant element. The efficiency of
conversion of the power in solar radiation to electricity has
increased from 1 percent, for the first cells produced in 1976, to
almost 12 percent for modest-area laboratory modules and almost 14
percent in 1987 for small-area laboratory cells. Higher
efficiencies, estimated at 18 to 20 percent, may be attained in a
few years with multilayer cells, each layer tuned to a different
part of the solar spectrum.
The Alabama Power Company has a 100-kW amorphous-silicon
generating field in operation at present. Efficiencies of currently
available commercial photovoltaics range from 5 to 7 percent.
Present-day manufacturing facilities are typically of modest
capacity, on the order of 1 MW/yr, at a cost of $1.50 to $1.60 per
peak watt. Within a few years, plants of 10-MW capacity per year
may be on line. These plants are expected to produce cells of 6
percent efficiency for about $1.00 per peak watt. A 50-MW power
plant to sell electricity to the Southern California Edison Company
(Chronar Corporation, anticipating a photovoltaic cost of $1.25 per
peak watt) and a 70-MW/yr production plant (ARCO Solar, Inc.) are
in the planning stage. Looking to the end of the 1990s and the
possibility of production levels of many hundreds of megawatts per
year, Ogden and Williams (1989) project that costs could drop to
the range of $0.20 to $0.40 per peak watt, based on reduced outlays
for specialty glass, labor, and depreciation, together with
commercial efficiencies increasing to 12 to 18 percent. Allowing
for electrical wiring losses and for dirt and dust on the modules
would reduce their overall efficiencies by an estimated 15 percent,
that is, to 10.2 to 15.3 percent. Land costs, site preparation,
array wiring, support structures, and other construction represent
additional area-related costs that would come to about $50/m2 with present technology, but economies
of scale might bring these down to $33/m2.
On the other hand, these figures are pertinent for the U.S.
Southwest, and supplying power to other parts of the country means
finding means other than electric power lines for energy transport.
Also note that these costs are much lower than that used in the
Mitigation Panel's analysis as described in Appendix J. Rather than
using projections of cost, the panel made a deliberate decision to
use only current cost in estimating the cost-effectiveness of
different energy options.
The cost for the electrolytic production of hydrogen depends on
the capital cost of the electrolyzer and the cost of the DC
electricity to run it. There