Gas condensing boiler with solar for hot water and heating - good?

Hello forum community,
can maybe someone here tell a complete layman if the following concept for our house is okay?!

Gas condensing boiler with solar for hot water and heating
Water storage tank: 750 liters
Collector size: 10 sqm
House size: 153 sqm
Prefabricated house ([KfW70-Haus])
3 people, possibly a child might join
Underfloor heating

If you need some more data, please let me know.
I would be very grateful for any assessments!

Regards,
hautameki

Hello,

....can someone here maybe tell a complete layman if the following concept is okay for our house?!

That depends on the demands of the builder. ;)
The price of the offer can only be evaluated in relation to the final energy (heating, hot water preparation, possibly ventilation, possibly cooling) of a real consumption forecast.
Solar thermal systems are only actually sensible on paper in most cases for a single-family house (primary energy).
In addition, general contractor offers often only reach the advertised efficiency standard on paper. When looking at the real conditions, this sometimes results in just an energy saving ordinance standard or even worse!
In other words, the building is too expensive in relation to what is actually delivered. This can easily be €10,000 and more.
In a concrete example, that was €46,000 too much paid sales price!
Prefabricated houses also often have problems with summer heat protection.

Best regards.