timonsku, (edited ) Yo, if you live in Berlin and have a sunny balcony/garden/window. You can get a plug-in solar setup for basically free.
This city subsidy program gives you up to 500€ for a setup and most only cost you around 300-400€.
Its basically free electricity for your apartment/home.https://www.ibb-business-team.de/steckersolargeraete/
https://www.berlin.de/solarcity/solarcity-berlin/im-fokus/foerderprogramm-solarplus/
E: Actually a lot more citites and even some states offer similar programs: https://www.vattenfall.de/infowelt-energie/solar/balkonkraftwerk-foerderung