Air heat pump or use gas and solar?

Just make a decision.

Just make a decision.

Everything was decided until a few months later I was told that what I had envisioned was not feasible at all. I think it’s normal to reconsider then. However, I agree with you that tomorrow I first need to find out how much more expensive it will be. In the end, I definitely don’t want to pay another 2-3 thousand euros extra for it.

As it looks, the installer will now simply lay the flat collectors at 15°. It will probably yield only 100 kWh less per year. That doesn't matter at all. The whole solar battery is just meant to satisfy the legislator anyway and serves no economic purpose. Hopefully, we will be happy with the solution then. The brine heat pump wouldn't have been much more expensive. But the trust is missing. Although the installer also confirmed to me today that hardly anyone actually takes out these 400 euro maintenance contracts. That would certainly have reshuffled the cards, but now it will probably be done this way. It might be different if he calls tomorrow and says that for this or that reason it is not feasible (without additional costs) after all.

...but I have never heard of long-term problems, and the technology is also quite old and has been used for a long time

Well, frozen probes, too high extraction rates, soils that no longer fully regenerate... those do exist, but it wouldn't stop me. And yes, some of this can probably be avoided through good planning and installation, but you rarely get deeply involved to be able to recognize planning/construction errors etc. But that applies to other energy sources as well...

The brine heat pump wouldn't have been much more expensive. But the trust is missing.

A slap in the face for everyone who would have to pay a 10k or more surcharge [emoji23] From my point of view, a drastic wrong decision given the circumstances, but you have to feel comfortable and have trust in your system technology, not me [emoji4] I'm curious to see how it will continue.

I believe it is difficult to assess this in advance. After all, there are also plenty of people for whom a heat pump does not operate efficiently. Even the energy consultant who did the heat demand calculation for the installer advised me to use a gas heating system. He deals with this every day. But if he calls me tomorrow and now sees problems or additional costs somewhere, I would still commission the heat pump without having sleepless nights.