Watch the output, not the calendar
Your monitoring app is the best guide. If production on clear days drops compared with similar days a few weeks before, and nothing else has changed, dirt is the usual cause.
What makes panels dirty faster
Gravel roads, farmland, building sites, coal or wood smoke, salt spray near the sea, roosting birds and trees that drop pollen or sap. Flatter panels hold dirt longer than steep ones.
A reasonable schedule
Two to four cleans a year suits most homes. Dusty farms and coastal sites may need more. After the dry season is a good time for one of them.
How to clean safely
Soft brush, clean or purified water, early morning or late afternoon. No detergents, no pressure washers, no scraping, and never walk on panels. If you cannot reach safely from the ground, book a professional.
