Solar thermal collectors convert sun energy to heat inside the collector is an absorber system.
The absorber traps the radiation inside, converting it to heat.
This absorber is made of a high-conductivity material (copper or aluminum) to increase heat transfer. It is treated with a selective coating to improve heat absorption. A heat transfer fluid, non-toxic antifreeze (propylene-glycol mixed with water), passes through the absorber.
Once warmed, this fluid transfers the heat energy to a hot water tank. A heat exchanger is used to avoid contamination of drinking water. This occurs within a separate closed loop system. Solar thermal systems can be used all year round. Thermal systems can provide domestic hot water.