Power consumption of a heat pump

I don't find a consumption of 50 kWh that high either. It's the total daily electricity consumption for a house

You can't be serious ... 50 kWh / day ... that would be around 18,000 kWh per year, which I also consider more than high, even with an electric car.

Photovoltaic yields are very low from November to February. Today I had a yield of 3.5 kWh and that was already a lot.

Where is that a lot? Here we had 21.8 kWh today. And such days occur from time to time. Even in winter. So far, December has brought 170 kWh here. November even 379 kWh. There is sun in winter too.

Where is that a lot?

If you are already asking where the place is, you should maybe write yourself where you are currently achieving your yields and with which performance basis. Otherwise, these are completely useless values and just casually written down. The weather situation in a country like Germany is simply not homogeneous. Here in the Erzgebirge, today was the first day with good yield, 2 more days with medium yield and the rest below average. Compared to the previous year, I am at just under 80% of the yield from last year's December.

Of course, the location is the beautiful Rheinland in NRW and the system has 10kwp.

That's nice for you. But you should also mention your system size. And that certainly has to be considered individually.
My system is designed for my needs, you surely have different ones.

In snow and frost, your system, which was certainly built with significantly higher investment costs, produces just as much as mine. That is, nothing!

Then please tell me how big your system is. Mine has 7.5 kWp and is completely sufficient for my circumstances.

A consumption of 50 kWh per day is completely normal for the months November through February. In the other months, consumption should then drop to almost zero thanks to photovoltaics. That's how it is with me too. Heating, hot water, and normal consumption like cooking, refrigerator, ventilation, etc. add up. I only need 6–8 kWh daily in winter, but still 1000 liters of heating oil for heat generation.
That is, seen that way, also 18,000 kWh per year extrapolated.

The fundamental problem is that you cannot retrieve the excess electricity from summer in winter. And respective long-term storage solutions are not in sight.

Of course, the location is the beautiful Rhineland in NRW and the system has 10kWp.

I really can’t believe that now. You can’t have that yield with a 10 kWp system. How much do you expect to have in summer then? This is not storytime here.