Cleaning instructions from Canadian Solar, Maxeon, Qcells, REC and LONGi manuals: water, pressure, chemicals, temperature and warranty risk.
By the SolarCleaningRated team · Facts checked against the sources listed below on November 1, 2026. General information, not professional advice.
Panel makers do not agree on every detail, especially water pressure, so the rule that matters is the one in the manual for your panels. Here is what five manufacturers say.
Its US installation manual says modules with sufficient tilt (at least 15 degrees) generally may not require cleaning because rain has a self-cleaning effect. It says to clean with water and a non-abrasive implement such as a sponge during the cool part of the day, not to use abrasive cleaners, de-greasers or unauthorized chemicals, and that damage from inappropriate cleaning will void the Canadian Solar warranty.
Its manual says to wash the glass with potable, non-heated water, that normal water pressure is adequate, and that harsh industrial-strength materials such as scouring powder, steel wool, scrapers or blades will void the product warranty.
Its Q.PEAK DUO ML-G9.X manual says not to use surfactants, rotating brushes, scrapers or any high-pressure water cleaning equipment, and to clean only modules that have cooled down.
REC's cleaning guide says ideally de-ionized water should be used, at ambient temperature, and that pressure or steam cleaners, high-pressure hoses, knives, blades and metallic sponges are not permitted and will invalidate the warranty.
LONGi's maintenance manual says the temperature difference between the cleaning water and the module must not exceed 10°C.
On this site, “Uses purified water” and “States a gentle method” mean the company says so on its own website.
41 companies in 5 areas, scored by the same published criteria.