Back when I got my RV the recommended cleaner for the Kitchen Floo..er, Roof (Same cleaner) was Spic & Span
I go up on the roof with a bucket, hose, long handled "Van Wash" Brush (or mop but I like the brush better) and a broom.. Sweep all the loose debris and return broom to ground, Fill bucket half full with water + Cleaner,, Brush well (Working a section at a time) and spray to rinse.. Move toward ladder refilling bucket with fresh water + Spic & Span as I go, and finally return everything to ground.
Today Dicor makes it's own cleaner,, but in 2005 they recommended Spic & SPan.