Solar thermal technology converts sunlight into heat, which is then used to produce hot water, heat or even cool buildings. Most solar thermal systems work in combination with a heater, for example a condensing boiler or a heat pump, which operates when heat demand is too high for the solar system alone. On average, a singlefamily house can satisfy up to 60% of its heat demand for domestic hot water with solar energy. A solar heating system is composed of: solar collectors, roof-mounted elements that collect energy from the sun, a hot water tank to store the water heated by the system, a circuit, and a heat exchanger to transfer heat from the collectors to the hot water storage tank.

Solar heat systems can also be used to top up central heating systems: in this case the saving on fuel is somewhere between 10% and 30% depending on the insulation levels of the building. It can be higher in the case of low-energy buildings. Solar thermally driven cooling systems – so-called solar air-conditioning – have a great potential, as the highest need for cooling goes hand in hand with the sun’s presence.