Decision on heating system (including list of investment costs)

Without underfloor heating, all variants would be outrageously overpriced.

You definitely have to include the drilling for [Sole], and then you are certainly about 10,000 euros above the gas connection with solar. If that is not the case, then [Sole]. But generally, gas should be the cheapest and least problematic!

With [Sole] he has some costs and surcharges included.. But I was also thinking about a flat solution... the prices with deep drilling somehow don't fit with air-water heat pump and gas either.. very strange prices

Gas drops out a bit, yes, but the difference between brine and air-water heat pumps is quite accurate.