Which heat pump to use in monolithic construction?

I didn't expect any other answer

Everything else would have been a lie anyway. I still think it’s not worth it, especially because here you only get a subsidy of about €1100 for a complete system (photovoltaic and storage) under the 10,000 Houses Program since August 2019, at this scale. There’s no retroactive funding at all.

I got an offer for the BYD high-voltage battery for €5700 in the standard configuration of 6.4 kW. You can easily upgrade it yourself (plug and play) with 1.32 kW blocks, for €670 per block. So it will then be a 9 kW storage. My problem is that unfortunately the car doesn’t fully charge from the system even in summer (in spring and autumn not at all, and we don’t even need to talk about winter), since I only get home at 5 p.m. That way, the car can be fully charged from the storage and there should still be 2-3 kW left for the night.

That’s the theory!

Has anyone actually taken the trouble to calculate when the whole topic of photovoltaics, storage, etc. pays off? Plus the currently expensive purchase of an electric car and the system?

That just doesn't pay off in a lifetime - and if it does, then only at a time when the first cheap China panels break down, right?

In our region, every general contractor advised against it back then - and normally they like to sell you everything.

Has anyone actually taken the trouble to calculate when the whole topic of photovoltaics, storage, etc. pays off?

Such calculations exist by the dozen. For every desired result.

Has anyone actually taken the trouble to calculate when the whole topic of photovoltaics, storage, etc. pays off? Plus the currently expensive purchase of an e-car and the system? It never really pays off in a lifetime – and if it does, then only at a time when the first cheap Chinese panels have broken down, right? In our region, every general contractor advised against it back then – and usually they are happy to sell you everything.

Photovoltaics should pay off after 11 years without storage if nothing breaks. Let's say 16 years. The car costs me 77€ per month including everything (insurance, electricity, service). Since I don't pay battery rent for it, the purchase will have paid off after 9 years (the payback is based on keeping my old diesel). And by pay off, I actually mean having recouped the purchase costs. Of course, that doesn't include provisions for a new vehicle. 3 years and 40k km have already passed. Controlled residential ventilation and geothermal exchanger probably never. Insulation and better roller shutter boxes, windows, etc. for KfW 55 minus subsidies will probably take about 30 years to pay off, estimated.

Has anyone actually taken the trouble to calculate when the whole topic of photovoltaic, storage, etc. pays off?

Yes, many have. My position is: Photovoltaics pay off solely through the feed-in tariff. The larger the system, the more economical it is. That’s why I got my 10kWp photovoltaic system 4 months ago; I don’t have more space. It will pay off after 11-12 years and then generate about €1000 profit per year until the subsidy expires after 20 years. Own consumption is just a bonus on top. The technology is robust, and there are long warranties. Storage simply does not pay off yet and is also not ecologically sensible because there is no surplus of "green" electricity in the grid. That means the electricity stored and consumed by oneself with losses in the storage could have been fed into the grid more efficiently for others. Car: no idea, that’s still to come. The new e-car is certainly more expensive than the comparison object.

Economic efficiency is always just one factor...

Ventilation system: Economically almost never, but offers enormous comfort gains

Battery storage: Economically rare, but there are definitely cases where it is (a friend of mine has a farm, now converted to selling organic meat with huge refrigeration systems running around the clock... a top use case)

Good insulation: Considering the higher value of the house, up to a certain point economically viable. However, the higher comfort should not be overlooked. Beyond a certain standard, hardly any further comfort improvement (in my opinion) is possible, provided there is a certain airtightness and the walls no longer get cold, as is common with older buildings. The added value (in my opinion) rather comes from continuous controlled ventilation (with pre-warmed air).

Electric car: I don't have one but am thinking about it. Can charge for free at work (+[Photovoltaik-Anlage] at home on the roof), thus the best conditions ... whether it is economically viable... secondary, e-car is cool

Otherwise, it's just like [Mycraft] says, you can always calculate in any direction with any assumptions if you need a justification for yourself.