Solar / Photovoltaic from an economic perspective

There are special heat pump tariffs (from some providers). However, you have to install and have a separate meter read (which costs again). We decided against it because it wasn’t cost-effective.

Alright, I just happened to read that in passing. Thanks for the clarification.

Isn't it currently the case anyway that the electricity used from the grid to operate the heat pump is subsidized or cheaper? Although the calculation could ultimately change again?

There are special heat pump tariffs (from some providers). But for that, you have to install and have read a separate meter (which costs again).
We decided against it because it didn't pay off.

We decided on the heat pump tariff because it probably wouldn't have paid off the other way around. Probably because in the first year the heating phase of the screed was also included in the annual bill of the heat pump tariff – so we will only be able to assess more precisely in the second year how much the heat pump actually consumes for heating/hot water.

Our heat pump tariff costs including tax (approx.) 0.187 euros/kWh. The regular electricity price is somewhere between 0.23 and 0.24 euros/kWh.
The first idea was to use our photovoltaic yield to support the heat pump. Then we would have had only a "double meter" (for regular electricity and feed-in). However, we would have had to bill most of the heat pump’s demand via regular electricity. That means each kWh supplied for the heat pump would have cost us about 0.05 euros more. The photovoltaic production in the (extended) winter months (including e.g., November and parts of October) was/is frighteningly low (see post above) and therefore unfortunately negligible.

We decided on the heat pump tariff. But this has the disadvantage that with the heat pump tariff we cannot support the heating with photovoltaic. However, as mentioned before, the largest consumption occurs during the dark season, so this disadvantage is limited.

How much does the second meter cost per year? I don’t know exactly: 50 euros? I should check – I once downloaded a list from Westnetz.
Let’s assume our annual heat pump electricity consumption is 4,000 kWh. 4,000 x 0.05 euros = 200.00 euros additional cost with regular electricity. 200 euros minus 50 euros (meter) = 150 euros difference when using regular electricity.
How much the photovoltaic yield actually affects now I can’t assess. In summer it is quite possible that the 2-4 kWh/day is completely covered by photovoltaic. The 10-25 kWh/day in autumn/winter/early spring, however, are hardly supported at all.

If the heat pump electricity tariffs are discontinued or approximate the price of regular electricity significantly at some point, I can still switch.

a total of about 8.7 kWh produced. Included is a "spike" upwards with 4.5 kW. Otherwise, the daily production ranged between 1-1.5 kW. Yesterday, the system topped it off with a massive 0.75 kW.

kW or kWh?

How much does the second meter cost per year? I don’t know exactly: 50 euros? I’d have to check – I once downloaded a statement from Westnetz. Let’s assume our heat pump’s annual electricity consumption is 4,000 kWh. 4,000 x 0.05 euros = 200.00 euros additional costs with regular electricity. 200 euros minus 50 euros (meter) = 150 euros difference when using regular electricity.

The difference is not 0.05€/kWh but rather between 0.02€ and 0.03€/kWh if you find a cheap provider, and the additional meter probably costs around 5€/month, so about 60€ per year. And since the larger consumption per meter also lowers the household electricity price, the additional meter simply doesn’t pay off.

If you then want to do "electricity provider hopping," by cashing in a new customer bonus every year and switching each year, you can probably get the kWh prices down even further.

The difference is not 0.05€/kWh but rather between 0.02€ and 0.03€/kWh if you look for a cheap provider, and the additional meter probably costs around 5€ /month, so 60€ per year. And since the price for household electricity also decreases due to the larger consumption per meter, the additional meter simply does not pay off.

If you also want to engage in "energy provider hopping" by snagging the new customer bonus every year and switching annually, you can probably get the kWh prices even lower.

That's right

We are currently paying 19.3 cents per kWh (including the basic fee as well as the new customer bonus), the contract is eight weeks old. I do not need a heat pump electricity tariff for that.