Solar panels are cleaned from the ground with a soft rotating brush on a telescopic pole, fed with purified water. No detergent, no pressure washer, and nobody walking on the array. Clean early in the morning while the panels are still cool.
What do you use to clean solar panels?
A soft rotating brush head on a telescopic pole, and purified water. The brush turns slowly so it lifts dust without scouring the anti-reflective coating on the glass. The water is purified — reverse osmosis or de-ionising resin — so the panel dries without a mineral film. A film is not merely cosmetic on a panel: it shades the cell and costs output, which is the thing you were cleaning to recover.
Detergent is left out for the same reason. Residue attracts dust faster than bare glass, so a washed-and-soaped panel soils again sooner than one cleaned with water alone.
Can you pressure wash solar panels?
No. A pressure washer forces water past the frame seals and into the junction between the glass and the laminate, which causes delamination and moisture ingress. It can also crack cells outright. The damage is usually invisible on the day and shows up later as reduced output, and it will generally void the panel warranty.
The same caution applies to temperature: never put cold water on a hot panel. The thermal shock can crack the glass. That is the practical reason panels are cleaned early in the morning.
What never to use on a solar panel
- A pressure washer. Forces water past the frame seals; causes delamination and can crack cells.
- Detergent or soap. Residue attracts dust, so the array soils again faster than if it had been cleaned with water alone.
- Cold water on a hot panel. Thermal shock can crack the glass. Clean early, while the array is cool.
- Abrasive pads or stiff brushes. They scour the anti-reflective coating, which permanently costs output.
- Walking on the array. Micro-cracks in the cells do not show on the day and never repair.
Everything on that list trades a short-term clean for permanent output loss, which is the opposite of the reason for cleaning.
How often should solar panels be cleaned?
It depends on what is landing on them. In dry, dusty inland conditions with long gaps between rain, soiling builds steadily and cleaning is worth doing far more often than on a coastal array that gets rinsed regularly. Bird fouling and pollen are the two things worth acting on immediately, because both shade the cell heavily in one spot rather than evenly.
For the machines themselves, see solar panel cleaning equipment, which sets out the 3.5 m, 5.5 m and 7.5 m reaches and the mains, battery and dual-power versions. The purification stage is covered under pure water systems, and working out the reach an array needs is covered under high reach window cleaning equipment.