Fuel cell or operating costs, photovoltaics and solar thermal?

Hello,
the whole topic has dragged on for us, so the actual decision has not yet been made - but the fuel cell is definitely out of the game. Regardless of the version, the fuel cell produces significantly more electricity than we will likely consume, and this especially affects the (financial) efficiency.
On top of that comes the relatively short lifespan.

In the end, it is not a real option for us. The initial costs are simply too high, and we would not be able to amortize the price difference compared to other solutions.

I am sure that the future of this technology lies in the mass market - with emphasis on future.

I meant the fuel cell heating system with gas? What do you mean by the home combined heat and power unit? I didn’t write anything about that or am I confusing something?

but the feed-in tariff for photovoltaics is currently pretty low (tending further down towards 0 cents?), so these feed-in tariffs are increasingly bringing less in terms of “paying off” the photovoltaic system. In other words, it will be paid off much later than years ago with good feed-in tariffs. Therefore I see it more as a problem when a lot of electricity is generated during the day, but not used by oneself and also not stored (without electricity storage, of course) and one no longer gets anything for feeding in. Or?

What also really annoys me is that you have to pay a kind of tax for self-used electricity. What is this “nonsense” supposed to be? Or is the sales tax in the private sector only for photovoltaic systems larger than 10 kWp?

so a “normal” gas heating? Yes, I also fear that you/we are a few years too early with a current investment in a fuel cell heating system.

What also really irritates me is that you have to pay a kind of tax for self-used electricity. What is this "nonsense" supposed to be? Or is the sales tax in the private sector only applicable to photovoltaic systems larger than 10 kWp?

Anyone who owns a photovoltaic system with surplus feed-in is self-employed. Therefore, the electricity does not belong to you privately, but to the business. If you want to use it privately, it has to be taxed. Just like a pub owner would have to pay tax on the beer they drink themselves.
For this, you can reclaim the sales tax upon purchase. Or choose the small business regulation, then both are omitted (but that is usually stupid).

but the feed-in tariff for photovoltaics is currently pretty low (tendency falling further towards 0 cents?), so these feed-in tariffs bring increasingly less when "paying off" the photovoltaic system

The return is not huge, but significantly better than investments with comparable high security. The feed-in tariff is lower than before, but the systems have also become significantly cheaper. If there is space, you simply build bigger and increase the yield. Only because of the lower tariff do we even talk about self-consumption. In the past it was more economical to feed everything in, but even today others are happy about your electricity.

So I see it rather as a problem if you generate a lot of electricity during the day but do not use it yourself

Why?

Even today you already have sufficient profit through feed-in. Self-consumption increases this profit further. Where do you see a problem? Apart from photovoltaics, I can't think of anything on a house that yields secure profits.

Of course it would be nicer if the sun shone at night, but that does (not yet) pay off and it doesn't have to.

What also really irritates me is that you apparently have to pay a kind of tax on self-used electricity. What is this "nonsense" supposed to be?

As explained before, you have the choice to do this. As a photovoltaic operator, you benefit from the tax system with the possibility to reclaim the 19% VAT of the system and after 5 years to switch to the small business regulation, under which you no longer have to pay tax on energy consumption. Unfortunately, it financially makes sense to take the most bureaucratic route.