The question of what a solar system on the roof can produce in terms of energy is one of the bases for the decision for one. That's why I find the following tool all the cooler, where I can see my own roof and the irradiation "amount". There's a lot more than that on the site, including a profitability calculator. Since renewable energy is not only fossil fuels and CO2, but through wise investment and the use of public funding often a saving factor in the wallet, I find this information great!

https://www.energieatlas-bw.de/sonne/dachflachen/solarpotenzial-auf-dachflachen

Just zoom in and then go to the calculator... ;-)