Solar panel cleaning becomes necessary when dirt and debris buildup starts reducing the amount of sunlight reaching your panels and cutting into your energy output. Studies consistently show that dirty solar panels can lose anywhere from 15 to 25 percent of their efficiency and in Southern California, where dust, smog, and coastal salt air are constant factors, that degradation happens faster than most homeowners expect. Properties in Palos Verdes, Redondo Beach, and Hermosa Beach deal with marine layer deposits and salt film on panels, while homes in Riverside and the Inland Empire contend with heavy dust and wildfire ash that can coat panels quickly.