To clean solar panels safely, shut the whole system down first, choose a cool time of day, rinse from the top with a gentle stream of water, use mild soap and a soft cloth or brush only for stubborn dirt, let the panels dry, then switch the system back on. Dirty panels lose output: dust, leaves and pollution build up over time, especially near expressways, factories, highways or airports, and poor cleaning can reduce performance by an estimated 15–25%.
8 Steps to Clean Solar Panels
- Shut the system down. Follow the shutdown procedure in the inverter manufacturer’s manual. Make sure the DC side is fully off; for the AC side, use the main solar supply switch.
- Disconnect rainwater collection. If gutters feed a rainwater tank, disconnect it temporarily so dirty runoff does not enter clean water storage.
- Choose the right time. Cold water on hot glass can crack it, and strong sun dries water too fast and leaves marks. Early morning is best, when dew has softened the dirt; otherwise a cool evening or a cloudy day.
- Rinse with a hose. Spray water directly onto the panels using a nozzle that reaches them safely.
- Apply water to the top surface only. Avoid water getting into the gap between the panels and the roof.
- Use mild soap and a soft cloth for stubborn dirt. A soft brush, plastic blade or cloth-covered sponge also works. Rinse off all soap with clean water and dry the panels to avoid water or soap marks.
- Use proper safety equipment on the roof. Water and soap make roofs very slippery. If you do not have the right equipment, hire professionals.
- Switch the system back on. When the panels are completely dry, turn the system on at the inverter and check that everything works normally.
5 Things to Avoid
| Avoid | Why |
|---|---|
| Hard water | Leaves residue that reduces efficiency |
| Abrasive sponges | Scratch and damage the panel surface |
| High-pressure water | Can damage the panel frame |
| Ice-cold water | Thermal shock can permanently damage panels; use water near panel temperature |
| Detergents and solvents | Can damage the panel surface |
Frequently Asked Questions
How much output do dirty panels lose?
Poorly cleaned panels can lose an estimated 15–25% of performance, depending on how much dirt builds up.
When is the best time to clean solar panels?
Early morning, when the panels are cool and dew has softened the dirt.
Does ONVALLA clean solar panels?
Yes. Solar panel cleaning is part of ONVALLA’s after-sale service for solar systems. See also solar warranty and after-sales, or contact us.
