Switching from gas to solar / photovoltaic with / without heat pump

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Storage is worthwhile starting at about 60 cents per kWh electricity price. So it really depends on your crystal ball whether you want to do it. With a heat pump, I would only consider adding a storage unit if you exceed 20 kWp. If the photovoltaic system is smaller, the heat pump otherwise leaves nothing for the storage. An electric car worsens the storage balance even more since it then hardly sees any kWh from October to February...

I can't think of any subsidies through loans (KfW). But from the Bafa, there is a 35-40% grant including everything for heat pump replacement against gas.

My own calculation (contrary to my previous opinion) is somewhat more favorable, in the range of 40-45 cents. But perhaps one should not view everything purely from a commercial perspective?

Furthermore: I have a brine-water heat pump, a BEV (with only 35.5 kWh battery), and a small 6.5 kWp photovoltaic system. Currently, I produce about 40 kWh daily. Only 15-17 kWh of that goes into the house (including heat pump and household electricity). It will probably be less in summer. At the moment, I simply cannot "fill" the BEV with the rest and "get annoyed" by every kWh fed into the grid. By the way, I am talking about a semi-detached house with 2 residential units and a total of about 130 m² living space.

But of course, it also depends on where the car is parked during the day (at home, at work?) and how optimized the heat pump is (when it starts, "heating up" the storage with sunshine). When dishwasher, washing machine, and dryer, etc., run. I see a lot of potential in optimization; you have more flexibility with a battery. Ours costs about €600 per kWh (RCT). So everything depends heavily on individual conditions...

By the way, I also hope that bidirectional charging will soon be politically desired and thus allowed. If then finally in 3 years the Munich startup with the Sion is ready... perfect.

Thank you for your answers. I will try to respond to them.

Solar thermal energy is never worthwhile.

Why not?

Is that why you always recommend photovoltaic + heat pump?

I hope the underfloor heating is designed for 30 degrees, because it has been renovated after all.

Yes, it is designed for 30 degrees.

Semi-detached house, renovation in 2014 sounds like a fairly manageable heating energy demand. How much gas do you need per year?
With that number, you can roughly estimate the heat pump capacity.

Our semi-detached house is 161 sqm, 2 adults + 2 children. 2 offices fully used + server running 18/7
Electricity consumption: 4600 kWh
Gas consumption: 28000 kWh

We don't currently have an electric car, but there should be the option to charge from home in the future.
Roof pitch: 33°, south-facing

Ours costs about 600€ per kWh (RCT).

Then the calculation with 45 cents is correct. However, most batteries are purchased for around 1000,- €/kWh.
However, with the small photovoltaic system, you probably won't achieve enough cycles to break even in the end. It should be at least about 200 times empty-full-empty if you want to recoup the costs within 15 years.

Why not?

Solar thermal energy and photovoltaics provide rather little in winter. Short days, low sun, often nasty gray weather. These are simply not the conditions for energy from the sun. In summer, it’s different, but the problem with solar thermal is the surpluses. In summer, you could heat an entire swimming pool with it, but you only need a few liters for showering. The rest just sits uselessly in the pipe. At least you can feed photovoltaic surpluses into the grid and get a little something for it.

Why not?

Because it either doesn't run at all when you need it, or runs full blast when you don't need it. And for something that can only contribute a really small part to reducing heating costs (5-15%), it is too expensive AND takes the premium spot for photovoltaics. The latter, in turn, can support the heating even in cloudy weather and still generate electricity in summer when the water is already warm.

When the Munich startup with the Sion is finally ready in 3 years ... perfect.

By the time the thing finally arrives, it will already be "outdated" and too expensive. No "normal" person will then get such a thing.