New heat pump for old buildings without renovation

I have a KFW55 house with solar hot water and gas (8600kwh gas/year heating+hot water) and underfloor heating. The new 6.8KW split air conditioner with 4 indoor units currently serves as heating. The issue of peak load coverage is one thing, but I will also turn off the air conditioner at -10 degrees and rather switch on the gas.

It is optimal: The gas heating then runs nicely in the optimal condensing range. The air conditioner's heat pump runs efficiently at moderate temperatures. I can calculate when what pays off using my electricity and gas rates.

May I ask how satisfied you are with the solar for hot water? Feel free to PM if this deviates too much from the thread topic.

I am extremely satisfied with the solar/hot water system. Heating support would have made no sense (whenever it produces, you don’t need it). Therefore, only 5 sqm.

September 2022:
611 kWh total energy

66.3% 405 kWh energy needed for hot water:
59.1% 361 kWh solar generated
7.2% 44 kWh gas generated

28.2% 172 kWh energy needed for household etc.
172 kWh electricity from the grid

5.6% 34 kWh energy needed for heating:
34 kWh electricity for air-to-air heat pump from the grid

Conclusion:
I have saved 361 kWh of gas which is 55€ at the current gas rate. In one month!
If someone asks me whether to choose solar or photovoltaics, I would first recommend solar. It’s a good thing and just two panels are more than enough for 2-3 people.
Photovoltaics are not worth it for me because I would have to finance it (still paying off the house loan) and I don’t have two electric cars yet (let’s see in 2040). Two photovoltaic panels don’t deliver anywhere near 55€/month :)

I am extremely satisfied with the solar/hot water. Heating support would not have made sense (whenever it delivers, you don’t need it.) Therefore, only 5sqm.

September 2022: 611 kWh total energy

66.3% 405 kWh energy needed for hot water: 59.1% 361 kWh solar generated 7.2% 44 kWh gas generated

28.2% 172 kWh energy needed for household etc. 172 kWh electricity from the power grid

5.6% 34 kWh energy needed for heating: 34 kWh electricity for air-to-air heat pump from the power grid

Conclusion: I saved myself 361 kWh of gas and that is 55€ at the current gas rate. In one month! If someone asks me whether solar or photovoltaic, I would first recommend solar. It’s a good thing and you only need two panels for 2-3 people, that is easily enough. Photovoltaics is not worthwhile for me because I would have to finance it (house financing is still running) and I also don’t yet have two electric cars (let’s see 2040). Two photovoltaic panels do not deliver anywhere near 55€/month :)