| Every day, more people are turning to the sun as an energy resource. SCE has used solar energy as part of its generation portfolio since the 1980s. Today, SCE buys 92 percent of all the solar power generated in the United States.
"In California, we are blessed with an abundant source of renewable fuel from the sun," said Stuart Hemphill, director, Renewable and Alternative Power. "We are encouraged by all of the initiatives and innovation taking place in the industry to take advantage of this plentiful source of power. Our productive partnerships with customers and developers will help assure Edison continues to lead the way in renewable power."
But how can energy from the sun help you tune into your favorite TV show or keep your refrigerator running? There are three main ways to harness and deliver solar power. |
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Solar Thermal Generating StationSolar thermal power plants, such as the ones located in California’s deserts, use curved mirrors arranged in large arrays which track the sun and concentrate sunlight onto tubes. The tubes contain a special fluid. The heated fluid heats water which is turned into steam. The steam is used to turn a turbine connected to a generator that produces electricity.
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Solar Dish Engine
Combining a solar dish and the closed-loop, non-combustion Stirling engine is a relatively new technology application, which also uses an array of mirrors to focus sunlight and track the sun. The mirrored dish concentrates the sunlight on a thermal receiver that converts it to heat. The difference in temperature between the focused sunlight (about 3,000 degrees F) and the surrounding air (about 100 degrees F) is used to drive a Stirling engine, which is connected to a generator that produces electricity. The Stirling engine, although not common, uses one of the most efficient energy conversion processes. |
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Photovoltaic (PV)
Photovoltaic cells convert sunlight directly into electricity. The word comes from the words photo (light) and voltaic (electricity).
The cells are made from semiconductor material such as silicon. When sunlight falls onto a thin slice of this material, the level of energy in the material increases, knocking electrons loose and causing them to flow.
In a PV cell, the flow is restricted to one direction. By placing metal contacts on the top and bottom of the cell, current can be drawn off. A device called an inverter is used to convert the direct current (DC) electricity coming from the array to alternating current (AC) at the proper voltage which is used by households.
 PV cells are wired into modules that are used to make PV “arrays.” An array can be stationary or it can achieve higher efficiency by tracking the sun. However, PV arrays cannot provide power at night, and PV system owners depend on an electric utility, like SCE, to provide power at night or during poor weather. A metering arrangement available from SCE permits extra electricity generated and not used during the day to be credited to the customer's account. |
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