Pellets with solar thermal or photovoltaic?

With me, no storage. 10kWp. The heat pump modulates between 300 and 1000 watts. Usually max 600 watts for hot water. In summer, I always have at least 500 watts, usually more, except during thunderstorms.

But hot water preparation is not the huge cost factor, and also the reason why solar thermal is not economical. I would focus on heating.

Air water heat pump .... is such a heater in acquisition so much cheaper than the pellet heater.

If you consider the area of the required basement space - YES. But since you are building the basement anyway and then simply want to spend 20 sqm x 2,000€ like that, the price advantage of course melts away (comparison of two equally powerful variants - whereby you definitely need a significantly smaller heat pump).

Viessmann Vitoligno 300-C pellet boiler, 12 kW, - according to the internet approx. k€ 12
Viessmann Vitocal 200-S air/water heat pump, 12.6 kW, according to the internet approx. k€ 7.5

Then there is the chimney, no idea what that costs (k€ 2-3?) as well as the chimney sweep annually.

Let’s just say the heating system with everything costs k€ 7.5 less than the air-water heat pump. At 30 cents electricity cost, that is 25,000 kWh electricity you could buy. That should cover the complete heating costs for 10 years - just the acquisition savings.

Why should a pellet heating system need 20sqm more space? When a heat pump then always without an outdoor unit. I don't want to have such a thing standing in the garden.

But the calculation is interesting. I have to work it out in more detail. Also in relation to consumption for domestic hot water.

As I said, a chimney will be installed anyway because of the fireplace in the living room.

Why should a pellet heating system require 20sqm more space?

No idea. Just an estimate based on pellet storage space, device size, conveyor screw, etc.

If it’s a heat pump, then always without an outdoor unit. I don’t want a thing like that standing in the garden.

There they are again, the prejudices
Put the outdoor unit on the garage or hide it behind plants. I have 7,500 reasons for that in my calculation...

But the calculation is interesting. I have to calculate it more precisely. Also regarding consumption for domestic hot water.

Domestic hot water is already included with the air-water heat pump. Of course, everything is just very rough and approximate calculations.

As I said, a chimney will be installed anyway because of the fireplace in the living room.

Then the advantage is naturally smaller, you only need the additional part in the basement.

If you only look at the costs, you won’t avoid an air-water heat pump. Just take a look at the heat pump consumption database de. There you can see real consumption and will realize they are not electricity guzzlers.

You can always calculate a lot.. You have to come up with a concept that fits the house, surroundings, possible subsidies, and your own condition.
I can calculate now too: air-water heat pump + photovoltaic + heating surfaces cost me about 20-22k with personal contribution. With that, I have about 50€ heating and electricity costs per year.

Why should a pellet heating system need 20sqm more space?

My parents have a pellet heating system, I think 20 sqm is not enough, the thing is huge, takes up a whole large basement room.

The garage is difficult to access (hip roof). Of course, you can hide them somewhere and they’re not very loud anymore, that’s true. It’s just simply a bad feeling with the heat pump. But I will take a look at the bill to see what such a pump really consumes.

I was thinking of the 20sqm additionally compared to a heat pump.
The bunker is about 2x3 meters and the heating itself 1.5 meters x 1 meter, so not that much.

Of course, it also depends on the size of the bunker and the burner.