Which heating system and how to combine it with photovoltaic / solar thermal?

Let's wait for the room-by-room heating load calculation.

Thanks to you all. There is no heating load calculation yet. I only have the appointment with the heating engineer. But I didn’t want to go into the conversation completely unprepared and wanted to have a rough idea of heating types / photovoltaic / solar thermal etc., so that he doesn’t try to sell me gas ;)

So what I took away: solar thermal makes no sense for our case, but photovoltaic is a good supplement to the air-water heat pump. I might upgrade the storage tank sometime, or maybe an electric car will become the storage for the house at some point (VW wants to start mass production with bidirectional charging in 2022, I read earlier), but that’s all still in the future... and regarding the car, I’m currently more than satisfied with my economical A3 with 1.4 TFSI, I won’t replace it anytime soon ;)

I would take a look at Viessmann. They offer very good packages (air-to-water heat pump + photovoltaics + battery storage). My brother-in-law has a quote where the storage (I think it was just under 8 kWh) costs about 1,100 euros as part of the package! Also, Viessmann is apparently releasing a heat pump with propane as a refrigerant later this year.

(I think it was just under 8kWh) in the package about 1100,- Euro!

If you don’t pay for that with inflated prices for photovoltaics or heat pumps, it’s a storage system that can pay off. I would take it too.

Also, Viessmann is apparently releasing a heat pump with propane as refrigerant later this year.

Aren’t the Vitocals already on the market? I thought so. Or they’ve just been announcing it for so long but not delivering.

My brother-in-law is supposed to still get the "old" one. I told him he should definitely insist on getting the R290... So far he has no information. But yes, the new ones should actually have been available since January.

I wouldn’t completely “put the ring trench collector on ice” ;-). I wanted to as well, but for me it’s definitely not possible due to the size of the property and boundary distances. Ring trench collectors can also be installed vertically! Then it just goes deep. Only a few heating technicians build something like that or agree to it. You just have to find the right one.

Build energetically sensible? Currently, I would say with rising electricity prices (my crystal ball says: they will never go down again):
Roof full of photovoltaics
If photovoltaics with a storage system become cheap or subsidized, use a storage system so that at least the nightly consumption (from evening dusk to morning sunrise) can be covered. By the way, it doesn’t all have to “add up financially” to “be worthwhile”!
A good alternative to a ring trench collector would be a brine-water heat pump (possibly with passive cooling)
Don’t forget summer heat protection (wall and roof construction)
Green flat roofs as well as dormers and garages (microclimate, roof membrane lasts longer).
Cistern for service water (like for washing machine and toilet!)

The initial investment may pay off late, but the house costs are very low in ongoing operation. For us, it was also or especially in hindsight the right decision to consider all these things.