You can use any of the commercially sold products for cleaning the roof or you can use Dawn dishwashing detergent. The important thing is not to use anything containing petroleum or petroleum distillates - will cause the roofing material to degrade very quickly. Personally, I use the off-the-shelf, made for the job, products.
I use this stuff:
Camco Roof Cleaner and Conditioner
My 2 cents, your mileage may vary...
2 Cats; J-Lo and Ragamuffin :R
2014 Thor Tuscany 40RX DP
2011 Ram 2500 Longhorn CTD HO
2011 Keystone Cougar 318SAB (now gone)
2008 FunFinder X 210WBS (Sadly gone)