New detached house with gas heating, but without solar

I have not yet seen a calculation in which solar thermal was profitable.

the topic is about circumventing the Energy Saving Ordinance?

I would be interested too! However, only academically, we are spending the money on an air-to-water heat pump ...

This is, as so often with our legislators, always the end customer who pays the extra cost. And everything around the house always gets really expensive. I guess I have to accept it: 36 cm T9 bricks, triple glazing, underfloor heating everywhere, wood stove and modern gas condensing boiler are not enough – solar or a heat pump must be added... of course without subsidies. If I wanted those as well, I would have to invest even more (external insulation, roof insulation, etc.).

What other cost-effective options would there be?