I only clean my roof when I am going to re-apply a EPDM paint, not every year. This happens to be a year that I needed to do some re-coating so I washed the roof last week. Tide laundry soap worked very well and washed off with no residue.
Be careful if you are going to stand on the roof while cleaning. A wet roof, especially with a soap product added, becomes like ice-Very slippery. I got most of it clean by staying on a ladder and using a long handle brush. I did around the AC, vents, etc. first, staying on my hands and knees with as little water and soap as possible, then hit the big areas from the side with the brush, soap, and hose.