Dirty Solar Panels
Solar panels are the one surface on your roof where being dirty has a directly measurable cost. In Central Florida they soil faster than almost anywhere, and most owners never check.
What soiling does to output
A panel generates from the light reaching its cells. Anything on the glass — pollen, dust, salt haze, bird droppings, organic film — reduces that, and the loss compounds quietly over months.
Uniform light dust costs relatively little. The expensive problem is partial shading: a single opaque spot such as a bird dropping or a lichen patch can disproportionately reduce output for a whole string of cells, because the array is limited by its weakest section.
That is why a panel array can look broadly fine and still be underperforming badly from a handful of concentrated spots.
Why Central Florida is hard on panels
Heavy spring pollen, frequent summer rain that deposits then dries mineral residue, and year-round humidity that lets organic film establish on the frame edges and creep inward.
Panels also sit at a shallow pitch on most Florida installations, so rain does not sheet off and self-clean the way it does on a steeper northern roof. Debris and residue sit.
Aluminium frames collect organic growth at the bottom edge, which then bleeds onto the glass above the seal.
What not to do
Do not pressure wash panels. High pressure can force water past the perimeter seal and into the junction box. That is an electrical enclosure — water there is both an output problem and a safety problem.
Do not clean them in the middle of the day. Cold water on hot glass risks thermal stress, and panels in full sun are live and hot.
Do not use abrasive pads or household glass cleaner. Scratched glass permanently scatters light, and some cleaners leave a residue film that attracts more soiling.
How we clean them
Low pressure, deionised or filtered water where possible, and a soft process that lifts soiling without abrading the glass or stressing the seals. No high pressure anywhere near the frame perimeter.
We work early or on overcast conditions rather than onto hot glass, and we clean the frame edges as well as the glass, since that is where organic growth starts.
Where panels sit on a roof that also needs soft washing, doing both together makes sense — roof runoff lands on the panels, so cleaning the array first and the roof afterwards is the wrong order.
Questions we get about this
How much output do dirty panels actually lose?
Doesn't rain clean them?
Is it safe to clean panels without voiding the warranty?
How often should panels be cleaned?
Related: All services · Soft washing explained · all FAQs