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

Almost 2.5 million households use solar thermal energy. The reason for its popularity: sunshine as a fuel is free and solar heating is uniquely efficient at the same time. Modern solar thermal systems provide 100 parts of heat from one part electricity for heating the house. This is because they require only a small amount of electricity for the solar circuit pump.

What's more, since the beginning of the year the state has been supporting solar heating systems with a subsidy of 30% - in combination with other measures even up to 45%. The reason for the subsidies is the environment.

Because the solar heating itself does not emit any CO₂ or other climate-damaging gases. If you operate the solar heating with green electricity, you heat completely CO₂-neutral.

The solar collector as heat generator

The basic principle of a solar heating system is very simple. A solar collector on the roof converts the solar radiation into heat. It does this via a thin sheet metal plate with welded-on tubes inside.

This sheet metal heats up by the sunlight. A special coating ensures that around 95% of the solar energy is converted into heat. A vacuum tube collector has a slightly different design. But this high-tech solution also uses such a highly efficient coating.

Regardless of the collector type, the heat gained flows via a pipe into a heat storage tank to supply your heating system or hot water supply from there. There is an anti-freeze solution in the solar circuit to prevent the system from freezing even on cold winter nights.

Solar thermal systems and photovoltaic systems use the sun as an energy source in different ways: solar thermal energy generates heat, photovoltaic electricity. A solar thermal system is usually used to support the heating system. You can use the electricity produced by the photovoltaic system in your own household or feed it into the public grid.

Solar thermal system for hot water preparation

Simple solar systems provide the solar energy only for hot water. Depending on the number of persons in the household, 4 to 8 m2 of solar collector surface are sufficient for this. The heat storage tank of a solar system for hot water heating contains drinking water.

With such a system you save up to 70% of your energy for hot water heating. In summer, the solar heat is usually sufficient and the boiler is occasionally idle, depending on the weather. When the sun's rays diminish in the autumn, the boiler starts to operate more frequently.

By the way: Your savings are particularly high if you also connect the washing machine and dishwasher to the hot water supply.

Solar thermal system for heating and hot water

For solar thermal systems that supply hot water and heating energy, in contrast to a hot water solar system, you need a combination buffer cylinder or, in addition to the DHW cylinder, a separate buffer cylinder containing heating water.

So that this system can also provide the solar energy for the hot water, a heat exchanger transfers the solar heat to the DHW at the tap.

Such a solar heating system with central heating backup requires a larger collector surface. This is the only way the system can still capture enough solar energy in seasons with less solar radiation and greater heating requirements.

The WOLF solar heating system

WOLF offers you a wide range of solar systems with vacuum tube collectors or flat plate collectors.

The WOLF solar heating system combines hot water and heating support. Modern control components ensure that the WOLF system uses energy particularly efficiently by automatically switching off the additional heat generator.

In combination with one of the storage systems, you can raise your entire heating system to energy efficiency class A+.

The WOLF Sonnenheizung® offers you a heating system that is perfectly matched to solar domestic hot water heating and backup heating.

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How much area does the solar system require?

The size of your solar heating system depends on how large the proportion of solar energy in your heat supply should be. Systems with a small collector surface save between 20 and 30% of the heating costs for heating and hot water.

With 20 m2 solar collector surface, the solar heating system can already cover up to 75% of the heat required by a well-insulated building with solar energy. It should be noted that for larger collector surfaces there must be more space for heat storage tanks. Even today, there are already houses that obtain their heat completely from solar energy with correspondingly large solar collector surfaces and heat storage tanks.

However, such a pure solar heating system is more suitable for new buildings, as the necessary conversion measures in existing buildings would be very extensive and expensive.

Solar heating possible for almost every building

In almost every house you can use the solar heating. In the best case, the roof surface is aligned as well as possible to the south and has an inclination of 30° to 70°. But even the installation on a west- or east-facing roof reduces the solar yield only insignificantly.

On flat roofs, the solar collectors can be mounted on top of each other. Alignment of the collectors to the south is particularly easy here. By the way: The steeper the roof, the better the solar system can capture the flat winter sun and provide heating support. Over the whole year, an inclination of about 40° is optimal.

Alternatively, the solar collectors can be mounted on the façade. However, if the roof and façade are in the shade of other buildings or tall trees, solar heating does not make sense.

New buildings are also well suited for solar heating. However, here there is the alternative of heating all year round with a heat pump. Heat pumps are therefore becoming increasingly popular in new buildings.


Whether in the garden, on the terrace or on the house wall, the WOLF CHA monoblock heat pump is strikingly inconspicuous and fits seamlessly into the design concept of your own home.

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Refined renewable energies Hybrid heating

Heat pumps are also a very good match for solar heating, because they are always particularly efficient when the flow temperature in the heating circuit is low. With a hybrid heating system consisting of a heat pump and solar thermal energy, a so-called renewable energy hybrid heating system, technically more sophisticated solutions are also possible.

For example, the geothermal heat pump can use the solar heat surplus in summer to heat up the ground. This improves the efficiency of the heat pump and at the same time reduces the size of the geothermal probe or ground collector.

The WOLF Hybrid+ solutions offer proven and powerful oil or gas condensing technology and environmentally friendly, reliable heat pump technology.

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Condensing technology matches solar heating

Since the sun provides only little energy in winter, the solar heating is always coupled with another heat generator to form a hybrid heating system. In most cases, the heat generators work independently of each other. The solar energy has priority and only when the sun is not shining, the second heat generator steps in.

In principle, any type of heating system is suitable for combination with solar thermal energy. The cooperation is particularly successful if the heating system works with low temperatures. This is where solar collectors work most efficiently. This is why solar heating is a perfect match for a gas condensing boiler, which reliably ensures efficient heating even at low temperatures.

Find out here about the highly efficient CGB-2 gas condensing boiler - the highest standard of gas condensing technology from WOLF.

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Solar heating: Individual advice

The investment in a solar heating system is worthwhile in most cases. With a technically correctly installed solar heating system, the collectors and the heat storage tank will last for decades and the solar thermal system can pay for itself quickly through the savings in heating costs.

Our WOLF experts will be happy to advise you and find a suitable solution for your building without any obligation.