Solar thermal systems use the sun’s heat to produce electricity. Mirrored surfaces concentrate sunlight onto a receiver that superheats a liquid. Energy from the scalding liquid is either used to produce steam or is converted directly into mechanical energy. In both cases the final product is electricity.

Solar reflectors are classified by how they collect solar energy. The three most common types are parabolic troughs, parabolic dishes, and power towers.

Parabolic troughs and dishes use mirrors shaped like parabolas to focus incoming radiant energy onto a fluid-filled pipe that runs down the center of a trough. Heat from the fluid is used to boil water in a steam generator to produce electricity.

Figure 9 Parabolic trough Golden, Colorado Source: National Renewable Energy Laboratory