What nations are you talking about? E.g. in Germany, you can buy up to 7kW of panels, screw them onto your roof, wire them up with controller and battery and feed up to 800W into local grid, no one is gonna stop you or anything (only thing you need to do is register online with the grid operator if you have >2kW of panels).

Legislation is, in fact, specifically made so people (i.e. landlord) actually can't easily stop you from doing this.