How Stuff Works has a great article on how to get the most years and production from your Solar Panels. This is a great read if you have or are interested in installing Solar Panels.
Their top five list includes, keeping the panels clean, how to clean them, keeping them out of the shade, monitoring them and keeping records of productivity. It is very important to remember that working on the roof can be extremely dangerous and that if you live in an area with hard water you are likely to leave water spots which will decrease the panels output. As a leading professional Solar Panel cleaning company in Hawaii, Envirowash Hawaii recommends that you or the company you choose to go with only use RO (reverse osmosis) or DI (de-ionized) water. This will help to ensure that the water is free from the impurities that cause water spotting.
5 Tips to Make Your Solar Panels Last | Craftster.org