The heating support is one of the most popular application areas of the solarthermics in private households as well as
in the industry. Heating support is frequently applicated in combination with domestic water heating. Pure heating
support is an expectional case.
What should be noted when planning a solar process heat system?
If you want to invest in a solar thermal system you should know the exact heat demand. This may be done through the
average annual demand of fuels like oil, wood and pellets or can be calculated through the final billing of the energy
Compared to solar systems for domestic water heating, heating supporting systems need larger installation areas.
Pure heating support requires on average approx. 4 m² installed collector area (20-30 tubes), depending on the
above-mentioned factors. With such system you can achieve a solar coverage of approx. 25 % – 30 %. These systems
can be combined and completed with all other fuels. The heat source changes only when the demand is not covered
by the collectors.
The average storage tank volume for a solar thermal heating system does not differ significantly of the usual
storage tank volume for heating water with approx. 600 l – 800 l. Per square meter 100 l storage tank volume
are needed. But the storage tank systems differ in their concstruction because storages for solar systems have
to contain heat exchanger for the solar circuit. Combined solar systems need combi storage tanks with two heat
exchangers, one for the heating circuit and one for the domestic water.
What is saved?
On average, solar thermal systems can save approx. one third of the heating demand annually.
Especially in the transitional period you can benefit from solar heating because the conventional heating system
is not needed.
100 % solar heating under which circumstances?
If you want to heat without any additional fuel the solar system needs to be dimensioned much larger. Per square
meter living area one square meter collector area is needed. Furthermore when dimensioning the storage tank volume it
should be minded that the heat needs to be stored over seasons.
Another important fact is the insulation, which should be at least KfW 40 building standard. Otherwise the complete
heating of an old building would be impossible, because the heat loss would be too high due to the missing insulation.