How Solar Panels Are Cleaned

Common methods

Purified water, which can dry with fewer spots
Soft-bristle brushes on water-fed poles
Gentle cleaning solutions, at some companies

Questions to ask

What water and products do you use?
Do you follow the panel manufacturer's cleaning guidance?
Do you walk on the roof or clean from the ground?
Are you insured if anything is damaged?

Methods compared

Method	How it works	Things to ask
Water-fed pole	Purified water through a soft brush from the ground or roof edge	Can they reach every panel?
On-roof hand cleaning	Crew on the roof with soft brushes and squeegees	How do they protect tiles?
Cleaning solutions	Gentle solutions for stubborn droppings	Is it approved by the panel maker?

What most panel makers caution against

Many manufacturers caution against abrasive tools, harsh chemicals and high-pressure washing. Check your panel's documentation and ask each company how their method fits it.

Related guides

Why water quality matters in SoCal

Much of Southern California's tap water is hard, meaning it carries minerals that can leave white spots when it dries on glass. That's one reason many solar cleaning companies use deionized or reverse-osmosis water for the final rinse. Ask whether the company brings purified water or uses your spigot, and how they handle spotting on hot days.

Questions

Is pressure washing okay for panels?

Many manufacturers and companies avoid high pressure. Ask each company and check your panel's guidance.

Why purified water?

Companies that use it say it reduces spotting. Ask what they use.

Why do companies use purified water?

Companies that use it say it reduces mineral spots, especially with hard SoCal tap water.

Is a cleaning robot worth it?

Robots are mostly used on large commercial arrays. Ask commercial providers about options.