Is this a fiberglass or rubber roof.
I have a fiberglass roof. Last year, June, I used a heavy bristle brush and cleaner comprised of Awesome, tide, soft scrub with bleach. I scrubbed small areas and hosed off. I still had some spots so I took a small pressure washer and used it also. I was able to the roof pretty much clean and white. I then used Zep commercial floor wax, 2 coats. The roof has stayed pretty much white. In October I washed again, everything came off with just regular soap, and then applied 2 more coats of Zep. It won't be nearly has hard to clean the next time.
I had a Class C with a rubber roof, never did get it clean.
2002 Monaco Windsor 38 PKD
2005 Jeep Grand Cherokee w/5.7 Hemi