My sympathy is limited given the consumption :p (you wrote unfortunately).
I hope I can report such a consumption next year as well.
I find the COP 4.2 too low, especially since the probe flow is really good (currently at the end of the cycle ~6°C and that towards the end of the season). I have a neighbor with an inverter heat pump and probe, and he is well above 5.
Apart from that, we are here in NRW. Of course, we also had an unusually strong onset of winter here, but that was for our conditions. Ultimately, you have to look at the heat demand that the building had.
: do you remember the extra cost of geothermal compared to an air-to-water heat pump?
Does photovoltaic also make sense with geothermal? (financially, not ideologically :p)
The memories are fading slowly, but it was in the range of about 1000-1500€ - after subsidies.
I also have photovoltaic and it already pays off on its own. Self-consumption is the icing on the cake.
It certainly contributes to the heat pump, I can’t say how much, although in winter the demand is relatively high but the yield rather low. Outside the heating season, one can probably say with a clear conscience that a large part of the hot water production is covered by photovoltaic.