A reasonable sized solar power system with around 10kWp and 10kWh battery costs at least 16k€ in Germany when done by a professional. Depending on your power consumption in general this can be a bad investment even with a heat pump. Therefore I would separate this from the costs of a hwat pump, since it is not strictly required.
Especially since you can get energy plans selling power for ~26ct/kWh.
A reasonable sized solar power system with around 10kWp and 10kWh battery costs at least 16k€ in Germany when done by a professional. Depending on your power consumption in general this can be a bad investment even with a heat pump. Therefore I would separate this from the costs of a hwat pump, since it is not strictly required. Especially since you can get energy plans selling power for ~26ct/kWh.