Switching from gas to solar / photovoltaic with / without heat pump

Now the question for me is how this works in winter & summer: Winter: I need a lot of heat, but the photovoltaic system does not produce enough electricity. Summer: I have too much electricity? --> Feed in? How do you deal with this issue?

Exactly like that.

In winter, you need as much photovoltaic as you can build. This means that the system per kWp becomes cheaper than a small one. The large amounts that you then feed into the grid in summer pay off the system and displace large amounts of coal power from the grid.

And since you are connected to that very grid, neither too little nor too much photovoltaic power is a problem.

I can't think of any funding via loan (KfW). But from Bafa, there is 35-40% on heat pump replacement against gas including everything.

Is there really nothing from the KFW for photovoltaics?

What funding options are there then? I might very much like to do it, but would definitely need a cheap loan.

Sort of. There is a loan from the KfW. But it is a completely normal loan without repayment subsidies and without insanely low interest rates. Also, the house bank has to offer it, which many do not like to do.

The reason why there is practically nothing is the feed-in tariff. A (now almost only nearly) 100% subsidy is sufficient. With proper self-consumption, every photovoltaic system breaks even in 12 years and still hasn't reached half of its lifespan. Photovoltaics have been a no-brainer for 20 years (with sufficient roof area). No more subsidies are needed.

In NRW there are still subsidies for the storage system (I don't know if this applies to you). €100 per kWh. Unfortunately, it has been reduced. For me, it was still €200. It can be applied for through the Bezirksregierung Arnsberg ([Förderrichtlinie progres.nrw]). Alternatively, inquire at the municipality or the district administration. In our area, the district offers, for example, a €1000 grant for the photovoltaic system. Regarding a loan, maybe ask at the local Sparkasse. I inquired there and was then offered an interest rate of 0.99% with a term of 6 years. This was apparently specifically for financing photovoltaic systems.

Can I actually start with the photovoltaic system and build the heat pump and storage later? With the heat pump, we have the problem that we have a very small garden and outside it would be “difficult” to implement. Also because of the appearance. Inside, I would only have one corner that would fit. But this still needs to be clarified