Can you pressure wash solar panels?
No. A pressure washer at 3000 PSI cracks the anti-reflective coating on solar glass and forces water past the frame seals into the junction box. Panels get cleaned with deionized water, a soft bristle brush, and roughly 40 to 60 PSI from a water fed pole. Anything harder can void the panel warranty.
Last updated: August 2026
We get this question on almost every solar quote. The homeowner already owns a pressure washer, the panels are visibly filmed over, and the roof is right there.
We tell everyone the same thing. Do not point it at the array.
What is actually on the glass
Solar glass is not plain tempered glass. It carries an anti-reflective coating, usually a thin porous silica layer, that buys the panel a few percent of output by cutting glare. It is measured in nanometers. A 15 degree tip at 3000 PSI held 18 inches away will haze it, and once it is hazed the panel loses more output than the dirt was costing in the first place.
The second problem is the seal. Every panel has a butyl or silicone bead where the laminate meets the aluminum frame, plus the junction box on the back. Those are rated for rain falling at terminal velocity, not for a stream hitting the edge at 3000 PSI from six inches out. Water that gets behind the laminate shows up months later as delamination or a corroded ribbon.
| Concrete driveway | Solar array | |
|---|---|---|
| Pressure | 3000 PSI | 40 to 60 PSI |
| Water | Municipal tap | Deionized, 0 TDS |
| Tool | 20 inch surface cleaner | Soft brush on a water fed pole |
| Detergent | Degreaser as needed | None on the glass |
| Risk if wrong | Etched stripe in the slab | Hazed coating, failed seal, void warranty |
Why tap water leaves the panels worse
San Diego tap water runs high on dissolved minerals. Rinse a hot panel with it and the water flashes off in the sun, leaving calcium and magnesium behind as white spots that bond to the glass. Now you have hard water etching on top of whatever dust you were trying to remove.
We run deionized water at 0 TDS for that reason. It dries with nothing left behind, which is the whole point. More on that in our post on white spots on solar panels.
What we do instead
Early morning, before the glass heats up. A panel at 140 degrees hit with cool water is a thermal shock risk and the water evaporates before the brush finishes the row.
The brush is soft bristle on a carbon fiber pole, fed with deionized water at low pressure. Two passes on most residential arrays. On a 20 panel system that is roughly 45 to 60 minutes, and we work from the ground or a ladder rather than walking the roof wherever the pitch allows, because foot traffic on tile is how people crack tiles and panels in the same afternoon.
Bird droppings are the one exception to gentle. They need dwell time with plain water to soften, then lift with the brush. Scrubbing them dry scratches the coating just as effectively as a pressure washer.
What array cleaning costs in San Diego
Most residential systems between 12 and 24 panels land at $150 to $300. Ground mounts run cheaper per panel. Second story roofs with a 6:12 pitch or steeper run higher because access takes longer than the cleaning does.
Coastal arrays need it more often. A system in Point Loma or Ocean Beach picks up salt film that inland systems never see, and we usually recommend twice a year there against once inland. That comparison is in our post on coastal versus inland cleaning intervals.
Last month on a Point Loma array off Catalina, the owner had already run a garden hose over the panels twice that summer with no change. The film was salt and it needed the brush, not more water. Production came back roughly 8 percent on the following week of clear days.
Full scope and pricing sit on our solar panel cleaning page and the Point Loma array page. If we cleaned your system, mention the neighborhood and panel count in your Google review, it tells the next person on your street exactly what to expect.