Do solar panels need cleaning?
Rain rinses most dust off panels tilted at 10 degrees or more. Dirt that does build up tends to collect along the bottom edge of each panel, which can shade the cells there. Bird droppings are worse, because they block light completely on part of a panel.
The simplest test is your monitoring. If sunny-day output has drifted down over months and there is no new shade, dirty panels are a likely cause. See solar monitoring.
How to clean solar panels safely
Check the manufacturer's instructions
Panel warranties can set out approved cleaning methods. Follow them to keep the warranty valid.
Clean early or late in the day
Cold water on hot glass can stress it, and water dries too quickly at midday, leaving marks.
Use water and a soft brush
A soft brush or sponge on an extendable pole, with clean water. Rainwater or low-mineral water avoids spotting.
Stay on the ground
Work from the ground with a long pole, or pay a professional with roof safety equipment.
What to avoid
No pressure washers, scourers, steel wool or strong detergents. Never stand on panels. Do not spray water at the inverter, isolators or cable connections.
Professional cleaning and inspections
A professional clean is often combined with an inspection of the isolators, cabling and mounting. That makes sense every few years, after a big storm, or if birds or possums have been nesting under the panels. Check the business has insurance and working at heights procedures, and ask for a report on anything they find.
Common questions
Many homes never need to, because rain keeps tilted panels clean. Flat panels, coastal homes, farms and homes with lots of birds may benefit from a clean every year or two. Let your monitoring guide you.
From the ground, with gentle water pressure, generally yes. Avoid pressure washers and do not spray the inverter or connections. Check your panel warranty for approved methods.
Light dust has little effect. Heavy grime along panel edges and bird droppings can cut output noticeably, because they shade parts of the cells.
Sources
Rules and program details come from government sources. Prices are industry averages, named and dated where used. Last checked October 2026. Prices include GST unless we say otherwise.