Thankfully, a simple soft washing can get rid of those black streaks, save you a lot of money, and completely transform your roof.
Softwashing involves treating the shingles to kill all organic matter, then rinsing all the grime away to leave your roof clean and protected. This is the only roof cleaning process recommended by shingle manufacturers. It safely gets rid of destructive blue-green algae without causing abrasion to the shingles themselves.