You will see '20% more power' on a lot of solar cleaning websites, including - fairly - on ours. It deserves a real explanation rather than a headline, because the honest range is wide and depends almost entirely on your surroundings.
What soiling actually does
A solar cell converts light. Anything between the sun and that cell reduces output. A uniform dust film scatters and absorbs light across the whole panel, which cuts production proportionally. Localized soiling - a bird dropping, a leaf, a lichen patch - is worse than it looks, because a shaded cell can drag down the output of an entire panel string.
Realistic loss ranges
- Clean suburban array, rained on recently: 2-5% loss
- Typical Florida array, 12 months since cleaning: 5-12% loss
- Coastal salt film or heavy pollen accumulation: 10-20% loss
- Bird droppings or nesting over multiple panels: 15-30%+ on affected strings
- Agricultural or construction dust, untouched for years: 20%+
Why the coast is different
Salt is hygroscopic, meaning it pulls moisture out of the air. On panel glass this creates a slightly tacky film that grabs and holds pollen, dust and organic matter instead of letting rain wash it away. That is why oceanfront arrays in Flagler Beach, Marineland and St. Augustine Beach soil faster than anything inland.
How to measure it on your own system
- Note daily kWh on a clear day before the cleaning
- Have the array cleaned
- Compare a similar clear day within the following week
- Compare the same calendar month year-over-year for a broader read
Most of our customers see the difference in their monitoring app within a day or two. If your array is genuinely clean and you would not gain anything, we will tell you that instead of selling you a service.