How large does the photovoltaic system need to be?

10kWp, 18k gross. Storage 8kWh 4.5k gross Maybe worth mentioning that the 10kWp is equipped with individual power optimizers. That might somewhat relativize the price.

Is it "only" 22.5k or is there additional labor cost?

are equipped with individual performance optimizers.

They are almost always unnecessary, expensive, and make the system prone to errors. One should only resort to them in extreme roof situations.

For the electricity consumption, I would go for about 12 kWP with a 15 kW battery.

Without the battery, the self-consumption would otherwise be too low. If an electric car is also going to be added, I would even install more than 12 kWP.

I read today that the first modules from Trina Solar with 670 Wärmepumpe are supposed to be available in Germany. That is of course a big deal.

that the first modules from Trina Solar with 670 heat pump are supposed to be available in Germany. That is of course a big deal.

All modules over 2sqm may only be installed outdoors in Germany and have no approval for mounting on the roof, in most cases these are max. good 400W.

The storage should be sized to get through the night. It is expected to be charged during the day from April to October, the remaining 4 winter months the storage will mostly not be able to be charged at all, as the generated power can be consumed directly during the day. In the summer months, more power is permanently generated during the day than can be consumed.

Assuming a constant consumption at night of 300W (in my opinion relatively high), 3.6kWh of storage would be sufficient for 12h of bridging time, therefore I would install a 5-6kWh storage in a single-family house.

Regarding e-cars, I do not think "intermediate storage" in the home battery is worthwhile. To store 100km, you would need about 20kWh of storage including losses with the associated costs.

If a heat pump is built, it uses much more in winter anyway than the photovoltaics will supply. Overall, a large battery rarely makes sense when you take the costs into account.

10kWp, 18k gross. Storage 8kWh 4.5k gross Maybe worth mentioning that the 10kWp is equipped with individual power optimizers. This might somewhat relativize the price.

For 10kWp, the price should be around 1300-1400 EUR gross to be reasonable. Anything else or significantly more expensive is not appropriate. The power optimizers also cost about 50 EUR each (around 30 pieces in your case?), so the higher price is not really justified here.

I mean, there was something good about the individual optimizers. I don't remember exactly, but I think one provider said that even without shading it can be advantageous because then I can put different roof sides into one string, and I even think I wouldn't need a second inverter without them (with full occupancy, 4 roof sides). Does that sound somehow plausible? If not, it could also be that I remember it wrong.