Photovoltaics are coming up - Options: 19 kWp, 25 kWp, 30 kWp, Storage?

I would take the available modules and start right away. Also a system size just under 30KWp with storage. Of course, in winter you don’t have enough yield for your heat pump. The roof also has a parapet and the sun comes very low in winter... But in summer you have enough electricity and even at night. An electric car also speaks for storage. So you can charge from the storage in the evening. Now there’s just a pool you want to heat sometimes... Unfortunately, I still had the 10kwp limit. Otherwise, I would have installed more right away.

(The power consumption still sounds high even for bathing 3-4 times a week, unless you fill the 700l tub every time.)

Yep. I also bathe that often, sometimes even more than 4 times a week, and we're under 3000 kWh for the heat pump. Smaller house, of course, but it can hardly be due to the bathing.

What technology is installed in the house? Large controlled residential ventilation? Network, cameras, NAS, etc. can also have significant power consumption.

There is quite a lot in it, KNX (switches with displays), automatic adjustment of shading throughout the day, etc., network with NAS + 8 cameras, a few TVs with Apple TV, HomePods, etc., but all of that runs through a separate meter.

No controlled residential ventilation, it is really just heating and hot water. Possibly the heating-up phase is still included in this value, since it was the first year of billing. However, I will address that topic separately. Regarding the topic here, I adopt the general consensus: as much as possible on the roof and storage, if at all, then for ideological and not financial reasons ;)

Is the electric car at home during the day? It makes no sense to charge the storage during the day and then use it to charge the electric car in the evening.

Although the charging losses are high, it is still cheaper than feeding in with a new system and buying expensively from the grid in the evening. We are not talking about old systems with high feed-in tariffs.