Yes, there is a difference, you are right. I don't have hard numbers at the moment (typing from the phone) but from looking it up quickly, the sun's intensity varies from about 950 kWh/m² to about 1.200 kWh/m² between north and south Germany. So, what OP described will generally work in any part of Germany.

Germany has a pretty consistent climate. Doesn't really matter where you live. Of course, that's an oversimplification, but if you're new to Germany and wonder "oh, what's the weather going to be here?", the answer pretty much is "similar to the rest of the country".

You could then look at a map of France and think, ah, similarly sized country, probably also has a consistent climate, but that's not true. Southern France is very different from Northern France. But Germany's climate is pretty uniform.