Solar thermal is a technology designed to harness sunlight for its thermal energy (heat). This heat is often used for heating water used in homes, businesses, swimming pools, and for heating the insides of buildings (space heating).
In order to heat water using sunlight, a solar thermal collector heats a fluid that is pumped through it. As the fluid is pumped through the collector, the fluid becomes heated. The now heated fluid then is pumped out of the collector and through a heat exchanger.
Heat exchangers are usually comprised of copper, and are normally found inside a solar storage tank. This allows the heat in the fluid to be transmitted - or exchanged, hence the name - into the water in the storage tank.
These highly effective systems are popular in many parts of the globe, from China to Canada to Zimbabwe. The panels are typically 70%-90% efficient, compared to around 20% efficiency for solar photovoltaic (pv) systems. Solar thermal energy displaces the use of the existing hot water heater and heating equipment, typically displacing either natural gas or electricity.