Solar Panel Cleaning Questions, Answered for Las Vegas Homeowners

Several things can do it: normal aging of about half a percent a year, a new tree or building shading the roof, a cloudier stretch, an inverter fault, or dirt and droppings. Compare clear days in the same month, allow for aging, and check for shade before paying for a cleaning. A solar panel inspection helps if the cause isn’t obvious.

Work it out from your own numbers. A 12,000 kWh system losing 5% to dirt gives up about 600 kWh a year, worth about $64 at 10.7 cents. Against a $100 to $250 cleaning, that takes more than a year to pay back. Droppings change the picture because they can also cause hot spots. The full math is in is solar panel cleaning worth it.

It is water with the minerals filtered out. Las Vegas tap water averages about 280 ppm hardness, and those minerals stay on the glass as white spots when it dries. Deionized water dries clear, and REC names it the ideal choice for cleaning its panels.

Rinsing isn’t banned, but water that runs off your property onto the street, sidewalk or gutter counts as water waste, with fines from $40 up to $5,000 for repeat violations. Keep the water on the roof and in the yard. Tap water will also leave hard water spots.

No. REC says pressure and steam cleaners are not permitted on its panels and will void the warranty. Other makers set hard limits on water pressure. A soft brush on a pole and a gentle rinse do the job without risking the glass, seals or coating.

Plain water and a soft brush handle most Las Vegas dirt. REC allows a mild biodegradable soap if you rinse right away, and diluted isopropyl alcohol under 10% for stubborn spots. Avoid acids, alkaline cleaners, abrasive powders and anything that scratches. Most solar cleaning products sold online aren’t needed.

It is possible if a panel or its wiring is damaged. Solar panels make electricity whenever light hits them, even with the system switched off, so cracked glass, burn marks or loose wires are a reason to stop and call a licensed electrician, not to start washing. Intact panels cleaned from the glass side are low risk.

It is the riskiest way to do it. Safety training from ISCA treats ladders as a last resort, and falls are a bigger danger than the panels themselves. A water-fed pole lets you clean most single-story arrays from the ground. If you are in a 55+ community or the roof is two stories, leave it to someone with fall protection.

Listen for cooing at sunrise, look for droppings on the patio, pool deck or cars, and watch for twigs or feathers poking out from the edge of the array. If birds fly straight under the panels and disappear, there is almost always a nest. See pigeon proofing for the fix.

They are wear and damage, not dirt. Browning is discolored material inside the panel, snail trails are thin dark lines that often follow tiny cracks, and bubbles or peeling mean the layers are separating. Cleaning won’t remove them. Get them photographed and checked with a solar panel inspection.

They should be clipped up to the racking. Loose connectors lying on the roof can wear through, collect water and arc, which ISCA lists as a warning sign. Don’t pull on them. Photograph them and call a licensed solar electrician or your installer.

ISCA, the International Solar Cleaning Academy, is a solar cleaning training group that held its first convention in Las Vegas in 2024 and teaches cleaning methods and roof safety. It is training, not a license. It is still worth asking whether a company’s crew has had formal safety training before anyone goes on your roof.

Before and after photos of each section of the array, close-ups of anything worth watching such as droppings, cracks, browning or loose wiring, the condition of any pigeon mesh, and a short note on what was done. You should be able to see the job without climbing up yourself.

Because it sells more cleanings. Most Las Vegas homes do well with one a year, plus a second after monsoon season when it’s needed. See how often to clean solar panels and check your own output before you agree to a schedule.