Some good moss killers for the roof are Spray & Forget Super Concentrated Roof Cleaner and Wet & Forget Moss, Mold, Mildew & Algae Stain Remover, according to Roofpedia.com. Another good product is Wash Safe Roof Wash.
Spray & Forget Super Concentrated Roof Cleaner is an eco-friendly, biodegradable product that does not need to be rinsed after it is applied to the roof. It is non-corrosive and does not contain harmful bleach, lye, acid or phosphates. Wet & Forget Moss, Mold, Mildew & Algae Stain Remover must be diluted with water before it is applied. Wash Safe Roof Wash is an environmentally safe product that kills moss by cutting off its nourishment.