Storage space and heating problem

The problem is the location...or is the house in Spain? Because there, air/air systems are great; in our regions, you have to weigh it up...because in winter, air/air basically means you are heating directly with electricity.

The problem is the location... or is the house in Spain? Because there, air/air systems are great, but in our latitudes you have to weigh it up... because in winter air/air basically means you are heating directly with electricity

We were assured that this is secured by the photovoltaic system and only on very cold days causes a power supply.

We were assured that this is secured via the photovoltaic system

One can expect that high heating demand (the cold and dark season) correlates with low photovoltaic yields. But certainly, the "assurance" has been supported with verifiable, valid figures showing that it does indeed work. I can only judge this intuitively and unfortunately cannot substantiate/refute it with concrete numbers.

We were assured that this is secured via the photovoltaic system and only allows a flow of electricity on very cold days

Good joke.
How many kWp are installed to secure this? Probably around 20 or more. And what sun shines on the cold night?
It doesn’t change the fact that it remains an electric heater. And no, self-generated photovoltaic electricity is not free.

Good joke.
How many kWp will be installed to secure that? Probably from about 20. And which sun shines in the cold night?
It also doesn't change the fact that it remains an electric heating. And no, self-generated photovoltaic electricity is not free.

Would the reduction to Kfw 55 and underfloor heating (I don't want any other one) really be a sensible alternative?

Would the downgrade to kfw 55 and underfloor heating (I don't want another one?) really be a sensible alternative?

You can also have underfloor heating and still do Kfw 40(+). Those are not mutually exclusive at all. Only the air-to-air heat pump should be removed and replaced by an air-to-water heat pump. But the provider will charge you for that. Just check online again about the air-to-air heat pump and decide if that is something for you.