Correct calculation by the energy consultant? Why solar for heating?

So I also need a small wind turbine. Still waiting for cheap cylindrical spiral-shaped ones that were talked about ages ago.

Hello Saruss, in the model home park in Wuppertal there is a house that has exactly such a wind turbine on the roof. I can't remember which manufacturer it is from at the moment. I wanted to go there again at some point and talk to the people about the device.

Best regards, Thorsten

What can we do?

Hi,

with gas heating, a portion of "renewable" energy is mandatory for KFW70.

Honestly: It doesn’t bring any benefit at all. But it’s a regulation. Even if you reach and fall below the values.

Domestic hot water solar thermal: It never pays off. 30-40 ct yield/day ./. electricity costs for circulation pump (5-10 ct/day) at best 170 - 200 days/year. A joke in a package.
With heating support: It only makes sense when using vacuum flat tube collectors (about twice as expensive as normal collectors). Because in summer / (large parts of) autumn/spring you don’t need heating in a KFW70 house. I know that because I also have one (with Q_p and H_t rather in the KFW55 range). In winter (let’s say from October - mid-March) a conventional solar thermal collector does nothing anymore except looking good on the roof (and causing capital costs). The vacuum collector brings a lot more in this regard. And as is well known: Especially in winter you need heating and precisely there the nonsense with solar thermal and normal collectors just doesn’t work. But in high summer you get 74-degree hot water for showering and nice hot bathing.

So choose the cheapest solution. Because you will never recoup the investment for this nonsense here in these latitudes. The whole thing is nothing more than a nice and unnecessary gimmick for the environmental conscience, imposed on the KFW70 house with gas heating.

Best regards Thorsten