Solar thermal systems are a technology that enables the direct conversion of the sun's energy into thermal energy, which is used to heat domestic water.
Solar thermal systems base their operation on a rather simple technology: the collector converts solar energy into heat that is transported via the heat transfer fluid to a heat exchanger.
The central element of solar collectors is theabsorber, which is a dark metal plate, treated with special coatings, under which the plumbing tubes pass. It is the absorber that converts solar radiation into heat. A glass cover and thermal insulation on the back make sure that there is no heat loss. Water circulates in the absorber which, by means of a heat exchanger, conducts the heat to theaccumulator; thus the heat can be used to heat water for domestic and sanitary use or for central heating.
During periods with little sunshine, hot water is automatically provided by auxiliary heating. To avoid problems in cold outside temperatures, the closed circuit of solar collectors contains antifreeze liquid. In some vacuum models operating with water, ice formation is prevented by keeping the liquid moving slightly without heat loss.
Each solar thermal system is complemented by an accumulator that allows heat to be stored and released as needed. Just as an example, for a hot water system for a single-family house, the accumulator has a volume of about 300 to 500 liters, this volume increases in solar heating support systems; in such circumstances, in fact, the water heater is often integrated into the hot water storage tank for heating.
