Why soiling matters more here
In climates with regular rainfall, panels get rinsed naturally. Los Angeles goes months without meaningful rain, so dust, pollen, exhaust particulate and bird droppings accumulate continuously through exactly the months when solar production should be at its peak.
What the loss looks like
Uniform light dust causes a modest percentage loss. Heavier accumulation, and particularly localised blocking from bird droppings or leaf litter, causes disproportionate loss because of how panels are wired — a single heavily shaded cell can drag down the output of an entire string.
Watch your production data
Most systems report daily output. Compare a clear day this month against a clear day shortly after your last cleaning or the last real rain. That comparison tells you more than any general estimate, because it is your panels, your angle and your conditions.
How panels should be cleaned
Deionised or purified water, soft brushes, no harsh detergent and no high pressure. Panel surfaces have anti-reflective coatings that abrasives and aggressive chemicals damage permanently. Hard tap water is its own problem — it dries and leaves mineral spotting that blocks light.
Frequency and safety
Twice a year suits most Los Angeles installations, more if you are near open land, heavy traffic or under trees. Roof-mounted panels mean working at height on a surface designed to be walked on as little as possible, which is a genuine reason to hire rather than attempt it.
Key points
Why soiling matters more here
In climates with regular rainfall, panels get rinsed naturally. Los Angeles goes months without meaningful rain, so dust, pollen, exhaust particulate and bird droppings accumulate continuously through exactly the months when solar production should be at its peak.
Frequency and safety
Twice a year suits most Los Angeles installations, more if you are near open land, heavy traffic or under trees. Roof-mounted panels mean working at height on a surface designed to be walked on as little as possible, which is a genuine reason to hire rather than attempt it.