Because your system only requires a minimal amount of maintenance, you can count on it to operate at maximum efficiency for quite some time. Cleaning will vary based on various factors, such as the tilt of your roof, the amount of rain you get, and the amount of debris around your system. The best thing you can do is to contact the solar installer for a cleaning schedule. Annual servicing is typically all you need to maintain the cleanliness, tightness, and overall functionality of your new system.