Is Dawn Dish Soap Safe to Clean Solar Panels?

Is Dawn Dish Soap Safe to Clean Solar Panels?

Dawn dish soap is not recommended for solar panels. It's formulated to cut grease, which strips the factory anti-reflective coating over repeated washes and can leave a soapy film that attracts more dust. We use a diluted, pH-neutral panel-safe soap or plain water with a soft brush, and skip dish soap on every job we run in San Diego.

Last updated: September 2026

We get this question almost every week from homeowners in Clairemont and Rancho Bernardo who watched a video online and grabbed the bottle under their kitchen sink. It seems harmless. It is not, and here is why.

What Dawn actually does to a panel surface

Dawn is built to strip oil off a roasting pan. That same grease-cutting chemistry goes to work on the thin anti-reflective coating most panels ship with. One wash won't ruin a system. But we've pulled panels off a Scripps Ranch roof last spring where the owner had been hand-washing them with dish soap every few months for two years, and the coating had gone visibly cloudy in patches.

Does dish soap leave a residue?

Yes. Dawn is designed to suspend grease in water, and that same surfactant leaves a thin film behind when it air-dries on glass, especially with San Diego's hard water. That film grabs dust out of the air faster than a bare panel does, so the panels get dirty again sooner than if they'd been left alone.

What should you use instead?

Plain water and a soft microfiber mop handles most routine dust here, since we don't get much rain between May and October. For panels with bird droppings or salt film near the coast, we use a diluted, pH-neutral solution made for solar glass, applied with a soft-bristle brush and rinsed with low-pressure deionized water so it doesn't spot.

A job that shows why this matters

A customer off Governor Drive near UCSD called us in June after two years of DIY dish soap washes. Output had dropped enough that her inverter app was flagging it. We cleaned the array with a water-fed pole and deionized rinse, no soap at all, and output climbed back within a normal range in about a week once the panels re-equalized with clean sun exposure. The coating damage from the soap years, though, doesn't reverse. That's permanent.

How often do San Diego panels actually need cleaning?

Coastal installs near Pacific Beach or La Jolla pick up salt film fast and often need a rinse every 3 to 4 months. Inland arrays in El Cajon or Santee collect more dust than salt and can usually stretch to twice a year. Neither schedule benefits from dish soap in the mix.

If your panels haven't been touched since installation, or you've been using whatever was under the sink, our solar panel cleaning page covers pricing and the water-fed pole method we run on most roofs without anyone walking on the tile.

And if we've cleaned panels in your neighborhood, leaving a review that mentions your area and what we cleaned helps other homeowners nearby find us on Google.