Spring is a good time to check that your solar panels are clean and your system maintained for the peak solar months ahead. Some households will be wondering whether it’s necessary to wash their panels or not, or to get in a professional solar panel cleaner.
Do what you can, up to a point
While you cannot service your own panels, you can keep them clean simply by hosing them down. Surface dirt or dust can reduce the panel efficiency by up to 50% over time.
Solar expert Lance Turner from Renew magazine says it’s important to look at the source of dirt, and to know what you can do yourself and when to call in the professionals.
Debris such as leaves and bird poo can block light, so anything that covers even a tiny part of a panel can reduce output. “Bird droppings can be particularly problematic,” he says. “Brush away anything that you can with a long-handled broom, if the house is single-storey.”
Solar panels can tolerate moderate amounts of grime without too much lost generation, and if your solar panels are mounted at a slope of more than about 10 degrees, then most dirt and the debris you can’t reach with a broom, should wash off naturally when it rains.
Lance says the angle of your panels can make a difference to how well they wash in the rain.
“Angled panels have the rain running across them so they get a decent wash. If your panels are installed on a flat roof with no tilt frame then they might need a more frequent hose down. The rain can pool on a flat panel and leave a muddy mark when it evaporates. Even on panels that have a shallow tilt, the dirt can pool at the bottom edge of each panel, partially blocking the bottom row of cells on each panel”.
If there hasn’t been much rain of late, or you can’t reach any debris with a broom, give the panels a light spray of water with a hose, while keeping your feet on the ground. Never use a pressure hose as it could damage your solar panels.
If the panels are particularly dirty then professional cleaning is recommended.
“Some areas are dustier than others, especially near farmland or next to a main road. These panels can get much dirtier and might need to be cleaned more often,” says Lance.
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To ensure your system is operating efficiently and safely, it’s recommended to have your solar panels serviced at least once every two years by a licensed A-Grade electrician.
Your installer might offer a cleaning service, done at the same time as other checks and professional servicing of the system. Getting your panels professionally cleaned is a good chance to get a visual such as cracks, chips and discoloration.
Or your installer might recommend someone just for the cleaning aspect instead. There are plenty of specialist solar panel cleaning companies so get someone with a track record cleaning panels. Anyone cleaning your system should use full safety gear, and not stand on or place anything on top of the panels. They should also avoid using harsh soap or chemicals – usually water is enough.
“Remember that a bit of dust and grime on the surface of the panels is normal, and cleaning them too often is probably not worth the cost or the risk,” says Lance.
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Reviewed 31 August 2023