You can receive funding of up to 50k. This includes drilling, pump, controlled residential ventilation, and even BUS systems (Smart Home) e.g. weather stations, etc...
For me, it would currently be a loss-making deal given the difference of 7500€ - 12,500€ that I would receive from the BAFA this year (36k costs), so 5000€ additional costs according to the new principle. And if I’m not even sure that I can apply for the KFW 153 until June, I am simply completely confused..