Electricity produced by PV arrays can be used immediately, stored in batteries for later use, or stored on the electric utility grid by using net metering. Top of Document Back to Energy Homepage Solar Thermal Systems Solar thermal systems use solar collectors to absorb the sun's light and change it into heat energy. Solar collectors heat a fluid, which is then used to provide either hot water for household use or heat for the home. Some thermal systems produce warm water that is used to heat swimming pools. This is done in collectors, which are usually mounted on the roof.
Some systems use an electric pump to circulate the fluid through the collectors.
In systems with heat-transfer fluids, the fluid absorbs heat from the collector and then passes through a heat exchanger. The heat exchanger, which generally is in the water storage tank inside the house, transfers heat to the water. Once the water is heated, either directly or via heat transfer, it is stored in a tank similar to a conventional gas or electric water heater tank. Sunlight passes through the glazing and strikes the absorber plate, which heats up, changing solar radiation into heat energy. The glazing allows the light to reach the absorber plate but reduces the amount of heat that can escape.