Environmental Engineering Reference
roofs, offering to subsidize about one-third of the cost.
In 2000, Los Angeles, California announced a goal of 100,000 roofs
covered with solar electric panels by the end of the decade. The Los Ange-
les Department of Water and Power began offering subsidies that would
reimburse buyers for half the price of each new solar energy system. For
an average home, a photovoltaic package may cost between $10,000 and
$20,000, including installation before the rebate.
The price of photovoltaics continues to drop and interest is contin-
ues to grow. States such as New York, Arizona, Florida and Washington
have joined California in a major effort to allow homes and businesses to
use solar power.
The systems are almost maintenance free, but panels must be cleaned
of dirt, dust and leaves. They need to be installed on roofs without shade
on south-facing roofs.
The reliability and cost of solar electric technologies should continue
to improve, although solar power only accounts for less than 1% of all
power consumed. The U.S. produces about 300 megawatts of electricity
with solar which is about the same amount produced by a mid-size tra-
ditional power plant. If solar energy is to provide a significant part of the
world's energy needs, the cost of solar must be competitive with other en-
ergy sources such as natural gas, nuclear or coal.
California has nine solar stations with 11 square miles of mirrors fo-
cused on steam drums that drive steam turbines. They can generate 413
megawatts (MW) of electricity which is less than 1% of the state's capacity.
Because the sun sets at night and is sometimes attenuated by clouds, the
plant production only averaged 0.3% of California's electricity.
They are supported by federal solar power tax credits along with
California's Public Utilities Regulatory Policy Act (PURPA) contracts and
renewable power subsidies. When these tax credits were interrupted for
eleven months in 1991, the plants' operator, LUZ, immediately went bank-
rupt then SEGS, an Israeli government corporation, took over operation.
One problem has been the cost of the solar panels. Los Angeles be-
gan its solar program after state legislators mandated that utilities spend
about 3% of their revenue on efficiency, conservation and renewable en-
ergy. For solar, the power department had $75 million to spend over a five
year period. The power department would pay $5 for each watt of solar
installed on a residence or business. Homeowners typically purchase a 1-
or 2-kW system meaning that the municipal utility paid between $5,000
and $10,000 of the cost. The systems that are eligible for rebates must be