Solar thermal is the name given to the harnessing of the sun's energy for hot water use. Typically, the system works by placing a heat collector (solar panel) on the roof that contains a fluid consisting of water and antifreeze that is heated by the sun. The heated liquid is passed back into the dwelling through an exchange coil in the hot water cylinder where the heat from the fluid is transferred to the water in the cylinder.
Generally solar thermal systems are not the independent form of heating in a dwelling; normal central heating systems often act as back-ups.Between 55% and 70% of a dwelling's hot water requirements can be met through solar thermal systems, thus dramatically reducing the amount of fossil fuel required. For a typical three-bedroom house, a solar collector of 4-6 m^2^, depending on type and orientation, may produce around 1500-1800 kWh.
There are two main types of solar heat collector:
Evacuated Tube
Flat Plate
