Electricity meter for heat pump in combination with BAFA and photovoltaic

Let the electrician connect an interim meter in front of the heat pump in the distribution panel. This has nothing to do with the official meters (or electricity tariffs).

A bidirectional meter for the photovoltaic system + heat pump and an additional interim meter in front of the heat pump?

"The amounts of electricity or gas taken up by a heat pump must be recorded separately. Peripheral consumers (electric heating rod; heat source pump, control) must also be taken into account. The amounts of heat delivered by a heat pump must also be recorded separately. In addition to external electricity and heat meters, which do not each have to be calibrated, energy balances that are already integrated in a heat pump are also permitted."

Just read the last sentence of your quote.
I don't know of any heat pump that is subsidized that does not have the corresponding integrated meters.

But clarify that again with your craftsman.

You only need an electric heating rod if the heat pump can no longer manage because it’s very, very cold or if the heat pump is broken; otherwise, with proper dimensioning, you can always do without it! And you should!

Read the last sentence of your quote. I don't know any heat pump that is subsidized that doesn't have the corresponding integrated meters.

Sure, but why make it simple when it can be complicated 8-)

Whether the heating element would have helped at all in the current example of our situation, I don't know 100% right now, but I've been thinking about such a thing for days. A few days ago, the gas heating in our rental building failed, so we have had no hot water for almost a week. That toughens you up when showering, but I've often thought about the heating element, which should still help us in such a case (heating failure) to at least warm the water, right? :)

The original poster wants to waste photovoltaic electricity heating water with a flange heater. And that is pointless when the heat pump can do this with 3-4 times the efficiency.

If there is a power outage, the inverter also shuts down the photovoltaic system. There are inverters with hybrid/off-grid functions. But they do not provide nearly enough power to heat 200-300 liters of water.

Exactly. The heating element is a backup solution for the heat pump. In the houses here in the residential area, which draw high and low tariff power, the heating is shut off by the municipal utilities during peak times. One could now operate the heating element with the standard tariff

You only have shutdowns if you want heat pump electricity. Apart from that, no one dies during a blackout period. The house loses hardly any measurable heat if you don’t leave windows wide open. You first have to use up hot water. I have also rarely taken 2-3 baths during a shutdown period (1-2 hours) and then got into trouble due to lack of hot water. ;-)

Nobody dies during a lockout period anyway.

Who actually brings up the topic of lockout periods here? The creator didn't even ask about that. With photovoltaics and separate heat pump electricity, it's already a real challenge. And sensible only in a few cases (financially speaking).

Who actually brings up the topic of blocking times here? The creator didn’t ask about that at all. With photovoltaics and separate heat pump electricity, it is already a real challenge. And it only makes sense in a few cases (financially speaking).

Just read the quote from the OP that I was responding to. ;-)