Pressure is the one thing a solar array cannot take. The glass is coated, the seals are the weak point, and the repair bill is measured in panels.
No. It is the single most common question we get about arrays and the answer does not have caveats. A pressure washer puts hundreds or thousands of PSI onto a surface that is engineered around a thin optical coating and a rubber seal, and both of those fail long before the dirt does.
The frustrating part is that it often looks like it worked. The panel comes out clean, the array looks better from the driveway, and the damage is invisible from the ground. What you notice later is that output did not improve the way you expected, or that it quietly dropped.
Panel glass is coated so that light enters rather than bounces off. That coating is microns thick. Force abrades it, and hazing or micro-scratching cannot be polished out. You have permanently reduced how much light the panel takes in.
Where the glass meets the aluminum frame there is a sealed joint keeping water away from the cells and the junction box. Pressure is very good at finding that joint. Water behind it causes corrosion and delamination, and neither is visible from outside.
Roof arrays carry live DC wiring underneath. Driving water into connectors is both an output problem and a safety one.
A wand aimed under a panel hits roof penetrations and flashing that were sealed for weather, not for a jet of water from below.
Most panel warranties specify cleaning method. Pressure washing is frequently named as something that voids coverage, which means the damage above is now yours.
There is a second hazard that has nothing to do with the panels. Cleaning an array usually means being on a roof, next to glass, with water, above live electrical equipment. That combination is why we do as much as possible from the ground with extension equipment and will tell you honestly when an array is not worth climbing to.
Early morning or evening. Cold water on hot glass is a thermal shock risk, and on a sunny afternoon the panels are hot enough to flash-dry anything you put on them into a film.
Most of what is on a panel in the Triangle and Johnston County is pollen, dust, and organic debris that lifts with plain water at low pressure. Do that before anything touches the glass.
A soft-bristle brush on a pole, with clean water. Nothing abrasive, no scouring pad, no household scrubber.
Soap that is not fully rinsed dries as a film, and a film on a panel is exactly what you were trying to remove. Where a cleaning solution is needed it has to be mild and rinsed completely.
Hard water dries as spotting, which is why the last rinse matters as much as the wash.
Sometimes, and less often than people expect. Rain handles a fair amount of ordinary dust on a tilted array. What rain does not clear is the stuff that sticks: heavy pollen in spring, bird droppings, sap and leaf litter under trees, and the fine film that builds where an array sits near a gravel drive or a construction site.
The reason to care is that shading is not proportional. A panel is wired in series with its neighbors, so a concentrated patch of soiling, a dropping or a leaf, can pull down more than its share of a string. Even coverage of light dust is a much smaller problem than one dirty spot.
Same rules on the glass, easier access, and one extra problem. Ground mounts sit close enough to soil that mud splash from heavy rain lands on the lower edge of the panels, and that is baked-on rather than dusted-on. It still does not want pressure, it wants soaking and a soft brush.
We clean arrays as part of solar panel cleaning across Clayton and the surrounding towns, using the low pressure method above, and we will tell you when your array does not need it. If you are not sure whether what you are seeing on your panels is worth a visit, call (919) 698-3669 and describe it, or send a photo.
“The black streaks on our roof were embarrassing. Gone in one afternoon and the shingles were not touched.”
“Did the roof and the gutters in one visit and showed me photos of everything I could not see from the ground.”
“Came out on a weekend when I needed it and the results were excellent. Real person answered the phone every time.”
The white film that comes off on your hand is not dirt. It is the surface of the siding breaking down, which is why washing the house does not fix it.
Read the guide →Around the houseTiny black dots stuck to the siding like tar, usually on the wall nearest the mulch bed. Not dirt, not mold, and not something a pressure washer will fix.
Read the guide →PricingNobody can price your driveway off a web page. Here is what a real quote is built from, why two bids on the same house can be a hundred dollars apart, and where the money actually goes.
Read the guide →We fly the roofline and show you the footage on the spot. You see your own gutters, joints, and downspouts on the screen instead of taking our word for it. It costs nothing and you are not committing to the cleaning.
Free for homes and businesses across the Triangle and Johnston County. No obligation to book any work afterwards.
Call (919) 698-3669 for a free quote. No obligation.
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