Should photovoltaic design be considered with the heat pump or not?

For more than two roof surfaces, you also need two inverters and that makes it expensive.

It depends on the size of the system. Your statement is not generally correct.

The fact is that a storage increases your autonomy compared to a system without storage. The storage basically serves to cover the energy demand in the house at night. It can also support the heat pump in winter. The heat pump operates with an electric heating element in winter.

However, the storage is hardly charged in winter. Or rather, the heat pump (which by the way always runs electrically, not only with the heating element – which, by the way, is not needed if properly dimensioned) needs so much electricity in winter that you don’t get very far with storage (my 10 kW system produced only about 120 kWh last December, that’s not much).

The storage, however, is hardly charged in winter. Or rather, the heat pump (which, by the way, always runs electrically, not just with the heating element – which, by the way, is not needed if properly designed) uses so much electricity in winter that you don’t get very far with a storage system (my 10kW system only produced about 120kWh last December, that doesn’t get you very far).

You are certainly right there. Since we haven’t even moved in yet, I unfortunately don’t have any long-term data. Regarding generation, I note that my system also produces electricity with little sun. Although it is limited, it is something after all.

It always produces something when it is light. But such a dull winter day often produces only 50W from our 6.5kWp, and then not for 8 hours. The profitability mainly comes during the transition period, when the heating is still running but the days are already longer and sunnier.

Economic efficiency is especially important during the transition period when the heating is still running but the days are already longer and friendlier.

Or in summer, when you can supply the air conditioning, pool pump, electric car, or similar at full power.

Depending on the weather, we currently consume about 15-25kWh per day for household and heating electricity with our 9kW heat pump. 2 adults, 2 small children in a renovated old building. Washing machine + dryer run almost daily, dishwasher sometimes even twice a day due to home office.

Right now (and again in autumn) is exactly the time when a storage system would be worthwhile, because at night, for example, at subzero temperatures, we sometimes use ~10kWh heating electricity and the sunny days are then followed by cold nights. We feed in up to 40-50kWh on such days with 12kWp facing south.

In really gray weather, the photovoltaic still covers our base load (~250-300W), which is pretty cool.

We don’t have a storage system and will probably not buy one for now as long as there are no good offers (the solar installer priced a 10kWh storage at 7,000€...). In summer, we never empty it at night, and in winter, it is usually not full during the day.

For example, at subzero temperatures, already burning about ~10kWh of heating electricity and just the sunny previous days then lead to cold nights. With 12kWp oriented to the south, we sometimes feed in 40-50kWh on such days.

Can't you set the daily temperature of the heat pump to 22-23 degrees and burn the electricity? And at night lower it back to 19-20 degrees, and then the heat pump hardly runs, the temperature in the house then drops slightly. This way you practically use your house as a heat storage, give it a try.