Solar-energy projects put the sun's rays to work in two ways: to provide heat--such as for buildings--and to produce electricity. While solar is responsible for only a tiny fraction of the electricity used in the United States and around the world, that share has been growing--and there are high hopes for the future.
Two Types of Power
There are two ways to produce electricity from solar radiation. The first is with a solar thermal power plant, which operates on the same general principle as other power plants, such as those that run on coal or oil: Heat boils water into steam, which turns a generator to produce electricity. In the case of solar thermal systems, the heat is provided by lenses and mirrors that concentrate and focus the sun's rays.
The second kind of solar power is a photovoltaic, or PV, system. Photovoltaic cells convert light energy directly into electricity. Solar panels are actually collections of PV cells.
Biggest Plant
As of 2010, the world's largest solar energy plant was the SEGS solar-thermal complex in the Mojave Desert of California, which has a capacity of 310 megawatts. At its peak production, it can generate enough electricity to power more than 230,000 homes. The facility, owned by NextEra Resources, consists of more than 900,000 mirrors covering more than 1,500 acres.
Biggest PV Plant
As of 2010, the world's largest photovoltaic solar energy plant was in Olmedilla, Spain; it has a capacity of 60 megawatts. The 13 largest photovoltaic facilities were all in Europe: seven in Spain, five in Germany and one in Portugal. The largest photovoltaic plant in the United States was a 25 megawatt facility in Arcadia, Florida, which ranked No. 14 in the world.
Total Production
According to National Geographic, the amount of energy that reaches the Earth from the sun in just one hour would be enough to meet the entire planet's energy requirements for a whole year--if it could be harnessed, that is. Solar power provides only one-tenth of 1 percent of the electricity used worldwide--and only two-hundredths of 1 percent in the United States, according to the Energy Information Administration. Even so, solar generating capacity has increased at a rate of about 20 percent a year for the past 15 years.
Goal
The Department of Energy has set a goal of producing 10 percent to 15 percent of the nation's energy from solar sources by 2030.
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