A safe way to clean home solar panels, what to use, what never to use, and when to leave it to a crew. Sourced to panel makers' manuals and NREL guidance.
By the SolarCleaningRated team · Facts checked against the sources listed below on November 1, 2026. General information, not professional advice.
Start by looking. REC, a panel maker, recommends cleaning when dirt can be seen on the glass. Your monitoring app is the other clue: output that slides through a dry spell and recovers after heavy rain points to dirt. Our guides to whether panels need cleaning and how often to clean them cover the research and the rainfall in our areas.
The best-practice guide for solar operation and maintenance from the National Renewable Energy Laboratory (NREL), Sandia National Laboratories and the SunSpec Alliance says to follow the module manufacturer's recommendations for any cleaning, and makers don't all say the same thing. Two examples:
Our guide to what panel makers say about cleaning compares five manufacturers' rules side by side.
Two risks stand out in the manuals: falls and damaged panels. REC says never to stand on, walk on, lean on or apply pressure to its panels at any point, and to use fall protection and personal protection throughout the cleaning when working at height. Maxeon says not to stand on, drop or scratch its modules, because doing so may damage them and void the warranty.
If you can reach the panels from the ground, for example on a ground mount or a low single-story roof, cleaning from the ground with a soft brush on an extension pole avoids both problems. If the only way to reach them is to climb onto the roof, leave it to a crew with fall protection; our guide to rooftop safety and licensing covers the OSHA rule that applies to workers.
A damaged panel can shock you. Maxeon says module cables carry direct current and are sources of voltage when the module is under load, that if the front glass is broken or the backsheet is torn, contact with any module surface or the frame can cause electric shock, and that damaged modules should be disconnected from the electric system immediately. REC warns that damaged panels can present a lethal shock hazard because of leakage currents, and that the risk is higher when panels are wet.
So look before you wet anything. REC says to inspect panels thoroughly for cracks, damage and loose connections before cleaning. If you find any, don't clean; call your installer.
Clean when the panels are cool. REC says cleaning should only be carried out when panels are cool, to avoid thermal shock, using water at ambient temperature. It says that means cleaning before the panels reach working temperature, for example in the early morning. NREL's guide adds a seasonal tip: schedule cleaning after the end of pollen season.
The sources don't agree on everything. NREL's general guide says not to use brushes, while REC allows a soft, non-abrasive brush. On pressure, REC bans high-pressure hoses, but Maxeon's manual allows large systems to be rinsed with high-pressure water after a cleaning solution, while saying normal water pressure is adequate. That is exactly why the manual for your own panels should settle it.
The warranty is the other reason to follow the manual. REC says its product warranty is only valid if the instructions in the installation manual are observed at all times, and that it accepts no responsibility for damage caused by improper or incorrect use, maintenance or cleaning. Maxeon says the harsh materials listed above will void its product warranty.
Hire a cleaner if you would have to climb onto the roof, if any panel is damaged, if birds are nesting underneath, or if deposits won't come off with water and a soft brush. Ask what water, pressure and tools the company uses, and whether its method follows your panel maker's instructions. Nests and droppings are covered in our bird proofing guide.
Not unless your panel manual allows it. REC says pressure washers, steam cleaners and high-pressure hoses are not permitted on its panels and will invalidate the warranty, and NREL's operation and maintenance guide says not to use high-pressure water. Maxeon's manual mentions a high-pressure rinse only for large systems.
Usually, but check your manual. REC says de-ionized water is ideal and that rainwater, tap water or diluted alcohol can be used as a second choice. Maxeon says to use potable, non-heated water.
Only what your panel maker allows. Maxeon's manual allows an over-the-counter glass cleaner or a 3 percent soap-and-water solution, NREL's guide describes a mild detergent recommended by the manufacturer, and REC says acid or alkali detergents must not be used.
41 companies in 5 areas, scored by the same published criteria.