Sunlight doesn't just put us in a good mood. Energy from the sun is also Germany's favourite renewable energy resource.

The sun is some 150 million kilometres away from the Earth, but is still our most consistent source of energy: every day, 10,000 times more energy from the sun reaches the Earth than is used by the entire human race. And that will remain the case for the next five to six billion years.

Happy person in the sun
The sun actually creates happiness. Whenever our skin is exposed to sunlight, the brain stem begins producing the happiness hormone serotonin.

Solar thermal energy is a way of making the sun's energy usable. This may sound complicated, but it simply describes the conversion of solar energy into thermal energy. Advanced solar technology can make use of this in the most varied ways imaginable.

  • Benefits

    • Free energy. Only the pump needs some electricity.
    • Completely environmentally responsible, because there are practically no CO2 emissions.
    • Relieves the burden on the conventional heating system.
    • Some 50 % of the energy needed for DHW heating can be provided by a solar thermal system.
  • Drawbacks

    • Maintenance required.
    • Additional pipework is required between the roof and the heating system.
    • Not every rooftop is suitable for installation.
    • Additional space is required for the solar cylinder.
    • Higher up-front investment (but greater potential savings later on).


Solar thermal systems can use solar energy in one of two ways: either exclusively for DHW heating or as backup for the entire heating system.

Solar thermal systems for DHW heating require on average a solar collector surface area of 4 – 8 m2 for a detached house and supply enough energy for daily needs. This means that water does not need to be heated using other heat generators, considerably reducing your fuel costs. During the summer months, the solar thermal system can often supply all of the energy required.

A solar thermal system for DHW heating and additional central heating backup requires a larger collector area of 6 - 14 m2. In that case, it also supplies heat for the central heating system. Solar central heating backup works best when combined with underfloor heating.


A solar thermal system is an attractive add-on to a conventional heating system. When you choose this advanced system, you reduce your use of fossil fuels, save money and protect the environment by reducing pollutants.

The perfect opportunity to consider adding a solar thermal system is when constructing a new build or replacing a boiler. Whether in winter, spring, summer or autumn – solar thermal and heating systems always work together efficiently.

The first rays of sunlight in the spring can even be used to heat the water in the cylinder. During this period, heating is supplied by the conventional heat generator. In the summer, the solar thermal system can meet almost the entire need for DHW supply by itself. In winter, the conventional heating system switches back on. That goes for hot water too, of course, whenever solar energy alone is not sufficient.


There are already more than 2 million solar thermal systems in use in Germany, supplying homes with free energy.

A solar thermal system can provide up to 65 % of the energy required annually for DHW heating. And in summer that figure can go right up to 100 %, which means that your conventional heating system can often be completely shut down during this time. As a result, you generate zero emissions and almost no operating costs. Sunny days ahead for both the environment and your bank balance.

A solar thermal system is a futureproof means of energy supply. The German Federal Office for Economic Affairs and Export Control (BAFA) rewards this fact by subsidising solar thermal systems for combined DHW heating and central heating backup. The application for the subsidy funding can take up to 9 months after the system is commissioned.


Solar thermal systems cannot be installed on every building. A few things must be kept in mind.

Solar thermal systems are installed on the rooftop using special mounting systems. The roof surface area must be large enough and have a slope of between 30 and 70 degrees. The collectors must be able to face south, south-west, or south-east. Of course, the roof should not be shaded by surrounding trees or similar. Listed buildings are also prohibited from having solar thermal systems installed.

And to ensure that you still have hot water long after the sun goes down, you will need a storage cylinder. Keep in mind that this requires a little space.

The quickest way to find out whether a solar thermal system would be a suitable enhancement for your home is to arrange a meeting with a specialist.