How to Clean Solar Panels Safely, and How Often to Do It

Clean solar panels with soft water and a non-abrasive brush or sponge, early or late in the day when the glass is cool. Skip pressure washers and harsh chemicals. Rain clears light dust from most tilted panels, so many homes only need a wash after bird droppings or a long dry spell.

When solar panels actually need cleaning

First Solar’s cleaning guide says rainfall is often enough for light soiling. Rain tends to leave behind the dirt that shades whole cells, such as bird droppings and fallen leaves. In dry, dusty places a crusty film can build up too. Trina’s manual adds that panels mounted flat, at 0 degrees, need cleaning more often, because they do not shed dirt the way panels tilted at 10 degrees or more do.

A look from the ground, or at your system’s app for a drop in output on sunny days, tells you more than a calendar. Evenly dusty glass with normal output can wait for rain.

How to clean solar panels step by step

Solar panel cleaning steps come from each maker’s manual. These follow First Solar’s and Trina’s; if your panels’ manual differs, it wins.

1. Check for cracks first. Both makers warn that cracked or broken panels can leak current and are a shock hazard, worse when wet. Do not clean a damaged panel; call your installer.
2. Turn the system off. Daylight voltage in an array can kill, according to both makers. Follow your installer’s shutdown steps so the inverter is off and the array is disconnected.
3. Pick a cool time. Clean early or late in the day, or when it is overcast. Trina says not to clean in the hottest part of the day, and both makers want the water close to the panel’s own temperature.
4. Rinse with low pressure. A garden hose or a water-fed pole is enough. Keep the spray away from the junction box and connectors, and off the back of the panel.
5. Wipe with something soft. A soft cloth or sponge works, as does a soft-bristled brush made of non-conductive material. Avoid anything that can scratch the glass or seals.
6. Dry hard water. Hard tap water dries into mineral spots, so squeegee the glass or finish with a deionized rinse.

What solar panel makers allow and ban for cleaning

First Solar and Trina Solar set slightly different cleaning limits, so check your own panel’s manual against this table.

The ammonia line matters because some glass cleaners contain it. If your manual follows First Solar’s rules, check the label before you spray.

Cleaning panels on a roof: when to hire a pro

Most of the risk in cleaning rooftop panels is the roof, not the glass. OSHA names roof edges and skylights among the fall hazards solar workers face, along with ladders. For maintenance workers exposed to a fall of 4 feet or more, it requires a standard railing, or where that is not possible, a personal fall arrest system or safety net. Trina’s manual adds that no one should stand on panels to clean them.

If a long water-fed pole reaches every panel from the ground or a stable ladder, you can do it yourself. If you would have to walk the roof or work near the edge, hire a solar cleaning company or your installer.

Cleaning ground-mount, RV and portable solar panels

Ground mounts and balcony panels are the easiest to clean, since you can reach the glass without a ladder. The same rules apply: cool glass, soft water and no spray into the junction box. If you have not built a mount yet, the solar panel mounts guide compares the options, and balcony and plug-in solar covers where small panels can go.

RV roof panels bring back the fall risk. Clean them from a ladder with a long pole where you can, and treat the RV roof like a house roof.

Folding panels for a power station wipe clean with a damp microfiber cloth on the ground. Keep water away from the cable and connector, and let the panel dry before you fold it. The guide to charging a solar generator covers how these panels connect.

Clearing snow and bird droppings from solar panels

Heavy snow on solar panels should be cleared in time, Trina says, because patchy melting can shade parts of a panel and cause hot spots. First Solar advises clearing the bottom modules first, with the same soft, non-abrasive tools its cleaning rules allow. On a roof, that usually means a pro or patience.

Soak bird droppings and pollen with water for a few minutes before you wipe, so the dirt lifts instead of grinding across the glass. The solar panels section covers the rest of a home system.