Photovoltaic power for heating: possibilities and limits

Anyone who generates his own electricity via a photovoltaic system will certainly consider heating the house with his electricity. You can read about the possibilities and where these possibilities reach their limits in this article.

Heating with electricity

Using electricity directly for heating is not always profitable. Electricity heaters are extremely inefficient with a few exceptions. They consume so much more electricity for the heating in your house than was actually necessary.

infrared heating

The just mentioned exception is the infrared heater. As a radiant heater, it works very efficiently and can be installed without much installation effort and very flexible. As a practical experiment of the University of Kaiserslautern has shown, the infrared heater is quite a viable alternative to full heating - all the more if you generate the required power itself.

There are different forms of heating elements available. In addition, you can heat your terrace effectively and efficiently on cool autumn days.

Problem: Storage capacity

If you live in a passive house or low energy standard home, it will not bother you. The standard heating value of the entire house is so low that the power storage will be correspondingly low.

However, storage technology is a limiting factor for houses with a higher standard heating value. So-called "solar batteries" are still very expensive - for a storage capacity of around 4.5 kWh, you already have to expect around 6,000 EUR.

Although there is a subsidy from KfW for solar batteries, you still carry the lion's share of the costs, and with 4.5 kWh, you probably will not come too far.

And getting power from the public grid to offset the periods of lower power output (namely, especially during the winter months) is not particularly profitable.

Electric hot water heating

If you use so-called thermal storage, and convert the electricity into heat energy, you have to dig deep into your pocket, but they have a more or less profitable method for a central heating system.

heat pump

Heat pump heaters also need electricity for operation. Again, the problem arises with the power storage or the compensation from the public grid, if the self-generated electricity is not enough.

Night storage heater

Theoretically, you can also "temporarily" store the electricity in a night storage heater and "recharge" the night storage heater with its electricity yield. Interesting is the possibility insofar as you can get quite cheap on additional electricity from the public grid - namely over-produced electricity from wind turbines. However, night storage heaters are not necessarily for everyone, and reloading the night storage heater brings both technical and legal issues.

Hobbyists solution

One innovator from Schwäbisch Gmünd recently found a way to heat with solar power: He supplies the heating elements in his hot water boiler with PV power.

The concept could be purely mathematical, if one uses a thermal storage, as already mentioned above, and how the inventor develops his own control system, in which every excess amount of electricity goes into a water heater and the Heizwasserspeicher.

Experts believe that such solutions are at least theoretically quite competitive with modern oil or gas heating systems.

Video Board: Hot Carrier Solar Cells | GCEP Symposium 2011