How often should you clean your solar panels?
Solar panel cleaning · 3 min read
The short answer: most homes in the Toronto area do well with a professional clean once or twice a year. Spring is the most useful time, and a second clean in fall helps if you have trees nearby.
Why it matters
Dust, pollen, bird droppings, leaves and film from the air collect on the glass and block sunlight. Less light reaching the cells means less power from the same system. Rain washes off some of it, but it rarely clears droppings, sticky pollen or the grime that builds along the lower edge of a panel.
What changes the schedule
- Trees overhead or nearby: leaves, sap and pollen build up faster.
- Birds: droppings bake onto the glass and can cast shade over a single cell.
- Low-tilt panels: dirt and water sit on them longer than on steep panels.
- Busy roads, construction or farmland nearby: more dust in the air.
- After winter: a spring clean removes the grime left behind when snow and ice melt.
Check your own panels
Do it safely
Don't climb onto the roof yourself, and don't use a pressure washer on panels. Hard spray and harsh cleaners can damage the glass and coating. A soft brush with pure water is the safe way, and early morning or a cloudy day is best so the water doesn't dry into spots. Check your panel manufacturer's cleaning guidance and your warranty before anyone cleans them.