Newly built single-family house KfW55 standard - How to heat?

The heat pump mainly needs electricity in the winter half-year when your photovoltaic system hardly produces any electricity anyway (it mainly does that from April to September). So forget about this idea. A photovoltaic system primarily brings money (from non-photovoltaic owners into your pocket), but not autonomy.

Of course, you can massively oversize your photovoltaic system and install a large buffer tank in the basement, but then you waste part of the electricity because a minimum amount of self-consumption must be used and is not compensated. Economically, this is rather not viable.

If you want real autonomy, then get a wood log or pellet stove. Or if you happen to have a livestock operation next to your single-family house, then by all means a biogas plant

The heat pump mainly requires electricity (winter half-year) when your photovoltaic system hardly generates any electricity anyway (it mainly does so from April to September). So say goodbye to this idea.