At HAWK Window Cleaning, we have the right tools to get the job done Effectively, Efficiently & Safely. We use a specifically formulated solar panel cleaning soap to help clean and Restores Photovoltaic Efficiency; the brush head is a combination of Boars Hair & Nylon Bristles that gets the bird poop and heavy dirt right off. There are Dual Rinse heads pumping out Purified water from our Filtration System that Guarantees a Clean Rinse. Having this service done once a year is recommended depending on the climate conditions in your area.