Upcoming funding for photovoltaic?

unfortunately not for existing systems. I don’t know more

That has not been decided yet. We will have to wait and see what will be published in the Federal Gazette. Skip the storage, as already advised. They are completely overpriced. What kind of consumers will you have? Heat pump? BEV? Then a storage unit is becoming less and less worthwhile, since there won’t be much left over and in winter, when you especially need it, you won’t get it fully charged.