Which heating system should one choose for a new building?

That's new to me, could you maybe explain that via PM?

What do you want explained there?
Photovoltaic electricity simply isn't free.

A 7,000 euro photovoltaic system delivers about 65,000 kWh in 20 years (depreciation), assuming 5% aging losses. So 10.77 cents/kWh.

On top of that comes the VAT. With a purchase price of a reasonable 24 cents (cheaper is possible but difficult), that's 4.56 cents.

That makes the kWh already cost 15.33 cents.

Then the ongoing annual costs. For me:
20 euros monitoring
60 euros (12 x 5 euro VAT pre-declaration)
50 euros (tax advisor pro-rated)

(Actually, it’s even more because you need a PC, internet connection, antivirus software, etc...)

But realistically, for me it’s about 4 cents/kWh.

The missed profit has to be taxed. Usually, depreciation and other expenses (own time/tax advisor/computer/software) balance it out so it’s about plus/minus zero.

That brings us to 19.33 cents/kWh solar power.

Condition: Neither panels nor inverter break down during the 20 years. In other words, the entrepreneurial risk is not yet covered. If you factor in an inverter replacement with installation after 10 years (current prices), that’s another 4 cents. So you’d be at 23.33 cents/kWh.

So: I don’t want to rain on anyone’s parade, but you should just see it realistically. You won’t get photovoltaic electricity cheaper than grid electricity, and what you feed into the grid doesn’t even pay for itself.

Then it is all the more amazing that many have it. I thought that self-consumption was still worth it. Well, learned something new again

Self-consumption is worthwhile compared to feeding into the grid. Whether photovoltaics are generally worthwhile is another question. However, it depends entirely on the location and the associated yield forecast, and especially on the investment itself, as the calculation by toxicmolotow shows. If you buy too expensively, you cannot expect a return.

You don't always have to have dollar signs in your eyes.

For us, it's just about breaking even, and yet we decided to do it. However, I don't expect any return.

You will be surprised about the declining performance of the collectors over the course of the year Schönbach in a few years the output plummets. The simplest things are usually the best. and all that heat pump stuff is a power hog. My recommendation is gas or oil with [kontrollierte Lüftung mit Wärmerückgewinnung] and a chimney

No, I will not be surprised about that.

1) Already taken into account.
2) Tell me something new.

Actually, I had thought lately that you give good advice. But right now it is turning into barroom clichés, unless you want to back up your statements with theses or refute my contributions.