Then ask the people who already received the innovation subsidy with air-to-water heat pumps last year without any problems. There too, 4.5 was the requirement. With a not too Siberian NormAT and not too good thermal insulation, it’s not rocket science.
After researching in another forum (I don’t know if I’m allowed to mention it here), several users report achieving an annual performance factor of over 4.5 after calculations. However, nobody has yet reported any concrete positive decisions from Bafa under the current funding conditions.
Also interesting there is a post mentioning a PVT system (hybrid photovoltaic system with heat generation that is usable for the heat pump). These are eligible for funding under the new Bafa funding conditions due to the coupling with the heat pump. Does anyone here know about this concept and can share some information? The technology still seems quite new to me (possibly therefore not yet fully developed?).