New detached house with gas heating, but without solar

Energy Saving Ordinance still had to be complied with. Maybe your architect has already calculated that?

Basically, the solar system (approx. 6m^2) was always included in the offer, so it was clear that the Energy Saving Ordinance would be fulfilled.

And now I had the idea: Is that really necessary? Could the Energy Saving Ordinance possibly also be met by choosing a slightly more expensive eco-tariff for gas (and/or electricity)?

If I waive the solar system, it will definitely be recorded in the construction contract that the system will be installed "by own work," so that the builder is not responsible. But that is also logical.

Our neighbors are also only two people and they rave about their solar system. Even in winter. Very low gas consumption. And in summer their heating is basically completely off. Hot water runs only on solar. You have to see it this way too: you do have more technology, but the technology will also last longer because it is used less. I would not do without the solar system. I would not save money at this point.

We are only two of us - and every morning, when the sun rays warm the roof, I let the warm water stream gently splash on my skin, I get such a nice saving feeling

I can well understand hirsls point. Payback period of minimum 25 years (BEFORE maintenance/repair costs)! As much as I like [Grundstück. alternative Energien]..... it really doesn’t add up financially and it certainly doesn’t look good.

I have not seen any calculation where solar thermal had been cost-effective.