Deposits of varying kind can collect on solar panels and reduce the amount of sunlight that can be converted into energy. Heavy rain in some regions, for example, contain large amounts of calcium which can build up over time on solar panels into a white crust that can substantially obstruct the amount of light that enters the solar panel and that is converted into energy. This means that solar panels must be constantly cleaned, which is a hassle as well as costly.
Solar panels must be cleaned where deposits obstruct the sun.