Which heating system for old buildings?

Hello everyone,

I would like to briefly present a specific case for discussion here.

My father lives with his wife in an old, relatively large house. I guess about 200 sqm. There is no energy certificate available, but I think the energy demand is quite high due to the old house.
The house is currently heated by 4 or 5 individual wood stoves. There is no other heating system. So no heating water distribution system with radiators or underfloor heating.

The whole thing should take place without major renovation work. So ripping out the screed and installing underfloor heating is out of the question.

At a fair, my father was offered electric heaters in connection with photovoltaics. Of course, that’s the least effort, but it means high initial investment costs.

What other ideas do you have?
Heat pump with heating distribution system and radiators is probably not very efficient, I fear.

Oh yes, the heating should serve to keep the house at a base temperature of about 15 °C. Everything above that should still be done with the wood stoves. The heating should simply ensure that not 20 cubic meters of wood have to be cut every winter, but maybe only 5. And also to prevent the rooms from cooling down completely during longer absences of 1 to 2 days.

I look forward to suggestions.

Best regards
Specki

Is pulling pipes and installing radiators also too much? Especially when there is a basement, the ground floor is very easily supplied with pipes from below, and on the upper floor, pipes can be hidden behind thick baseboards, for example.
If that is an option, gas (if available in the street), oil, or pellets are possible. The latter, however, require space in the basement.

But I’ll put it pragmatically.
If it’s mainly about the effort of chopping wood, just don’t do it yourself anymore. Buy a splitter, a helper, or simply buy the wood ready-made. Because no matter which heating option you choose, it won’t be cheap. Even infrared heating or the like requires investment and electricity, so you might as well just buy the wood ready-made and leave the „right“ solution to the next generation.
I consider the photovoltaic system to be pointless. During the heating season, photovoltaics yield hardly anything and therefore actually have nothing to do with the heating system.