Construction costs are currently skyrocketing

Then please calculate not "roughly" but exactly. First, how you come to 2000 kWh yield from the roof, second, for which summer consumption you want to save it. Or, you know what, spare yourself that. In the last 6 years, I didn’t even reach half with my 5m2, on average 800 kWh. With 13ct/kWh for gas, I saved about ~100 euros this year. How much that was in the previous years (with a kWh price < 3ct for gas) you can surely calculate yourself.

I’m asking my colleague. From April 2022 to October 2022 he had no burner because it was defective. With 5 people in the household... But I already suspect that he will contradict your figures... But I’m not mad about that. Everyone should do it as they think. And whoever has the money can gladly throw it away... I have 2 children, I cannot waste my coal... sorry. Because, that has to be said clearly sometimes... in this forum there are many forum members who, consciously or unconsciously, have no children... Without children, you can of course plan quite differently...

... So I paid just under 1,000 EUR for my 5m² solar thermal panels. ...

I would be interested (as a former ST owner) to know where on earth you can get 5m² of ST for just under 1K. Of course including installation, the necessary scaffolding, the required solar storage tank, the control system, the solar piping (really expensive). Basically all the little things that are included in the price of a photovoltaic system here on the forum. Really, I have a genuine interest in finding out. I thought I got mine about 15 years ago at a bargain price of around 4K including installation and the aforementioned "little things" since my brother-in-law installed them and had good contacts at Weishaupt... But maybe I was ripped off?

Yes. But you’re not calculating... My solar thermal system for 1,000 EUR roughly saves me 2,000 kWh over the entire summer, so at the current gas price it’s 1,000 EUR. So it pays for itself after one year.

Where can I find this “current” gas price? I find values between 13-18 ct/kWh…

what says is not entirely wrong, from around April to early October you have more than enough hot water (we with our 300l storage tank). Our solar thermal system was put into operation at the end of 07/2016, as of today the meter shows 37,610 kWh, which would be about 2250€ at around 6ct gas, which we did not have to spend on gas. Has the system paid off? No, I don't think so, because I didn't know the extra cost of the solar thermal system, it was just included. But I think the extra cost was definitely more than this 2250€. Well, this year it will probably have to give way to the 28.xx kWp photovoltaic system because in my opinion I can easily make up the approximately 30€ (or rather 60-100) more that I would then have to pay as a gas advance. Because after about 5.5 - 6 years (if my current electricity costs per kWh remained the same for that long) the photovoltaic system would have paid for itself. But I wouldn't throw away or give up the solar thermal system, because what I have, I have and what I still need, I don't know :cool: These are my experiences with it

Aha. Someone who doesn’t know that screw connections are loaded in tension is explaining solar thermal to me. So I paid just under 1,000 EUR for my 5m² solar thermal panels. That gets me through May to October without a gas burner... good deal, I think. The neighbor paid 15,000 for his 10kWp system and feeds into the grid in summer for 6 cents/kWh. Do you want to calculate the rule of three or should I do it? It’s quite complex, did you ever practice that in secondary school? In the meantime, you can stick some screws into the wall and hang heavy cabinets on them without loading the screws in tension ;)

All your numbers are once again complete nonsense from start to finish and not really worth commenting on. You’re just a troll. Now the cost price for solar thermal panels from the hardware store, which of course has nothing to do with a complete, turnkey system, is being compared to an equivalent photovoltaic system. Heating support, which was the topic before, is of course not achieved with that either. 2000kWh energy savings for hot water in summer is huge nonsense. Oh, and the gas costs 12 cents at your place? Suddenly you’re calculating completely differently... Sorry, your posts are and remain embarrassing, I don’t even know how a proper screw connection works or how one could research that.

I also don't know why we are now talking about the amortization of an obviously price-conscious self-installed 1000€ ST, when the system from costs ten times as much. That is a completely different scale. Sure, for 1000-2000€ (if that figure is correct ...) it can be done once, but with an investment of 10k€ one should reconsider whether to save one’s money first.