Separate meter and electricity tariff for air-to-water heat pump sensible?

With what power? There are versions from 4kW to 8kW heating capacity - then at full load it draws between 800 watts and 1,600 watts per hour.

Sorry, our Daikin has 8kW.

That is actually the simplest and ultimately also the most accurate result. There are heat pumps that "measure" their power consumption. But they often forget standby operation or the pump power. The best is to have a meter BEFORE the fuses on the DIN rail. Of course, only if you are interested...

Too bad, apparently ours doesn’t do that :-(.

Then I have to talk to the photovoltaic guy. Since the beginning of the year, I have been diligently recording all meter readings of the two meters as well as the amount of heat generated by the heat pump in order to be able to do an evaluation. Unfortunately, I do not understand the whole system 100% yet. I have one tariff for heat. Basic price €10.66/month and 20.52 cents/kWh and one for household basic price €11.69/month and 32.57 cents/kWh.

Too bad, apparently ours doesn’t do that :-(.

Then the sub-meter before the heating fuse helps.

You can also determine the approximate heating consumption for pure heat generation (without water) by noting down the values of the main meter daily over a year and thus comparing heating periods with non-heating periods. This gives you an average daily base load (including hot water generation), which is of course not entirely exact due to seasonal effects (more light in winter), but at least provides a first reference point.
I did it that way for the first few years, but then had a sub-meter installed as well. Much more convenient and accurate.
With a photovoltaic system, that wouldn’t have worked anyway.

Household base price €11.69/month and 32.57 cents/kWh.

Either you leave the bonus out of your calculation or your household electricity is significantly too expensive.

We are letting everything run through one meter for the time being.

Then make sure you get a meter box that can accommodate a second meter if necessary.

Sorry our Daikin has 8kW.

What kind of "palace" is that that requires an 8 kW heat pump? "KfW100", 300 sqm, location? How to determine the heating demand at least approximately without a separate meter has already been mentioned.