So having 100€ savings in a year for a 200€ panel is a bad deal for you? Seriously 200€ is cheap enough for nearly all German households to afford them. What you are essentially doing is give most German households the ability to produce their own power, greatly enhancing fair power distribution, lower the electricity bill for them and give valuable capital most of the population. The only draw back is that they produce 30-50% less electricity, but forcing that would mean that you support big corporations building those solar panels, which only helps the rich.