Air heat pump with central ventilation system

Thank you for your comments. So better to do without the solar system on the roof (it could be retrofitted more easily later) and keep the ventilation system instead... now looking at it, that also makes sense.

That would mean that KFW 40 + is no longer possible but KfW 40 is still doable...

At the beginning we were against a controlled residential ventilation system because our general contractor also did not recommend it. We did some research on the internet and decided to go for it after all.

And whether you install controlled residential ventilation or solar systems? If anything, I would do both. I would only install a storage system if there are subsidies for it, which depend on the state. As already mentioned, the solar system is the only thing that pays off for the house and that you "get paid back." Another thing to consider would be a geothermal heating system. Then you don't have the ugly thing in front of your house, and the brine-water heat pump is considerably more efficient than the air-water heat pump. Costs should also not be much higher.

... Costs should also not be much higher.

Well, the additional cost for drilling is certainly noticeable.

Well, the additional cost for drilling is definitely noticeable.

For us, it would be about 5,000 euros. However, we have to make do with flat collectors because it's a water protection area. The price was the same as for the air-to-water heat pump.

For us it would be about 5,000 €.

However, for the OP - depending on the soil conditions, etc. - it can be quite different.

We have had a central ventilation system with heat recovery for many years (aluminum cross-flow heat exchanger and heating coil). We would never want to do without it again. Due to self-installation, it was feasible for < 3k€.

For the sake of understanding, we should talk about solar thermal energy or photovoltaics. Otherwise, there will be confusion. Photovoltaics certainly makes a lot of sense. ST probably not.