A solar energy plant uses the power of the sun to produce electricity. The sun emits solar radiation, and certain devices such as solar panels are designed to react to this radiation and convert it into electricity. Most solar energy plants use the thermal power of the sun to heat reservoirs of fluid and power turbines. Parabolic troughs, solar dishes and solar power towers are the three most common types of solar thermal power systems used to mass-produce electricity in solar energy plants.
Many solar energy plants utilize solar radiation to heat fluids to high temperatures and create steam. In a turbine, the kinetic — or moving — energy of steam is converted to mechanical energy, which causes the turbine to rotate and produce electricity. The energy produced by a rotating turbine can be harnessed and stored in a generator. While burning fossil fuels also creates the steam necessary to rotate turbines, utilizing solar radiation is a much cleaner, more energy-efficient approach to creating electricity.
A large-scale parabolic trough solar energy plant opened in California's Mojave Desert in 1980. This facility produces a considerable amount of the area's energy, deriving it from renewable resources. Parabolic trough systems feature reflectors that focus rays from the sun onto receiver pipes. Fluid is heated as it flows through receivers and creates steam, which is fed into a turbine and generator system. Certain parabolic trough systems, such as the system in the Mojave Desert, are linked with fossil fuel combustion systems designed to compensate for cloudy days and other low solar energy periods.
Solar dish systems employ solar collectors that are designed to track the sun, moving to absorb the greatest amount of solar energy at any given time. These systems concentrate solar energy at the dish component's focal point, heating liquids. A solar energy plant that uses solar dishes compresses and heats fluid to rotate turbines and produce electricity. While parabolic troughs can heat liquids to temperatures averaging 750 degrees Fahrenheit (398.9 degrees Celsius), solar dishes offer working temperatures that can exceed 1,380 degrees Fahrenheit (748.9 degrees Celsius).
Heliostats are essentially flat mirrors used to track the sun. A solar power tower can be linked into a solar energy plant system containing hundreds or even thousands of heliostats. These heliostats are arranged in a fashion that directs the sun's rays at a tower, which contains a heat-collecting fluid. Large-scale solar power tower operations are very efficient and may provide an economical source of electricity for the future.