Do you clean you panels?

Dirt can reduce panel efficiency by as much as 10%. Don't clean them if you don't feel like and if you're getting enough power. I don't think mild solvents like ammonia in Windex would hurt rubber roof. Even if you splash acetone or methyl alcohol over, it will hardly affect the rubber. Especially acetone as it evaporates quickly. I had to prep my rubber roof when installing the panels, and can tell you that it takes a lot of rubbing with Methanol to partially remove the paint coat.