Hose the solar panels down: This will leave hard water spots on the photovoltaic solar panels, reducing the efficiency. It will not clean the solar panels very well; it just washes off some of the dirt. You could crack the solar panels if you use cold tap water on the hot solar panels.
Use chemicals or detergents: using chemicals or detergents could damage the solar panels. It will also leave a residue, which holds onto dirt, reducing efficiency dramatically.
Use a Squeegee: The surface of solar panels is not smooth like glass. It has a frosted glass feel. So if you use a squeegee to clean solar panels the dirt and detergent will be settling in all the little groves while you squeegee off the top layer of dust and detergent
Use a company that does not have proof that solar panel cleaning in included in their insurance: We spend thousands of dollars a year extra in insurance that includes solar panel cleaning. Most insurance companies will not pay anything for damaged solar panel as they are so expensive, so make sure the person working on your large investment has the proper coverage.
What you should do...
Either you should spend a lot of money on equipment and training seminars, or you could contact us, and have them professionally cleaned.