Bafa: Renewable Energy Heat Pumps with Test Certification

These were initial experiments, the actual heating load is somewhere around 7kW.. I also have 230m² to heat.

The statement of the diagram is decisive for the calculation of the annual performance factor according to VDI 4650, because the bivalence point is important.
I just wanted to show THIS - how to determine the bivalence point.

According to the standard (and that is the only thing that matters for the subsidy), from the bivalence point -10° on, 100% compressor operation applies.
It makes no difference whether monoenergetic and bivalence point <= -10° or monovalent.

In reality, you will notice a difference. But not in the standardized calculation!

At -9°, I would no longer have reached the 4.5.

Those were initial fiddlings, actually the heating load is somewhere around 7kW.. I also have 230m² to heat.

The message of the diagram is crucial for the calculation of the annual performance factor according to VDI 4650, because the bivalence point is important.
That alone was what I wanted to show – how to determine the bivalence point.

According to the standard (and that is the only thing that matters for the subsidy), starting from the bivalence point -10° 100% compressor operation applies.
There is no difference whether monoenergetic and bivalence point <= -10° or monovalent.
In reality, you would notice a difference. But not in the standardized calculation!
At -9° I WOULD no longer have reached 4.5.

Yes, 100% compressor operation may apply there (which is logical in itself), but still, even for the calculated determination of the annual performance factor at the bivalence point, the performance factor there also plays a role. Therefore, in the end this point is not that important. More important is how the heat pump’s performance factor curve behaves/what COP values it has.
The thing about 9kW was not meant to be "mean," just as a tip. With my KfW70 house, I could heat over 350m² (extrapolated) with that.

As far as the COP is concerned, you are of course right. It is not only about the snapshot A2W35, but about the whole range. And for power-regulated ones, it also depends on the load.. which does not make it easier.

As far as I know, three values are relevant for the annual performance factor according to VDI 4650, A-7, A2 and A10. The rest in between is then interpolated.

I cannot and do not want to calculate such an annual performance factor myself. The note with COP >= 4.2 was just to make an initial preselection in the list, and THEN use the annual performance factor calculator. It makes little sense to calculate a heat pump with a COP of 3.5 at A2W35, whose COP could theoretically be so good at -7 that it manages it, but that is extremely unlikely. In the end, everyone cooks with water.