Do dirty solar panels reduce output?

Angel Oquendo Owner, Sunshine Solar Panel Cleaning · Waianae

A solar panel makes power from the light that reaches the cells. Anything sitting on the glass between the sun and the cells takes some of that light away. It's that simple, and on Oahu there's a lot that can sit on the glass.

What's on Oahu panels

• Red dirt. The plateau and the Leeward plain: Mililani, Wahiawa, Kapolei, Ewa. It blows on, rain streaks it, and it collects along the bottom edge where the panel meets the frame.
• Black mold. The wet side and the valleys: Kaneohe, Manoa, anywhere shaded. It grows as a film across the glass.
• Salt. Anywhere near the water. A haze that looks like nothing from the ground and is very obvious on the before video.
• Bird droppings. Corrosive, and each one shades a few cells. A shaded cell stops producing and can turn into a hot spot.
• Paint overspray. After a house repaint, as one customer pointed out in his review.

Why rain doesn't fix it

Rain alone won't clean your panels, just as rain alone won't clean your car. It streaks the dirt and leaves it, and it doesn't touch mold or salt at all. Then the sun bakes what's left.

What customers saw

We don't put a percentage on your roof, because we haven't seen your roof yet. But customers have written down what they saw in their own monitoring after a clean, and those are their numbers to share:

• One wrote that his panels went from producing about 2 kW to over 8 kW after the clean.
• One said her Enphase app showed roughly 25% more power the same week.
• One wrote that since the first year we cleaned his panels, his electric bill had stayed at the minimum charge except for one month of near-daily rain.
• One with 12 years of accumulated crud called the difference in output tremendous.

Every one of those is on our reviews page, in their words. Every roof is different; the before video tells you what yours has on it.

The other thing dirt hides

Dirt also hides damage. A cracked panel, a missing fastener, a wire hanging under the array: you don't see it from the ground and neither does your app until it fails. That's why the 5-point inspection happens on every clean, and why the drone flies with thermal imaging on commercial arrays. Hot spots and micro-fractures show up as heat, and the report is what you take to the manufacturer under warranty.

What to do

Look at your panels. If they look like the before photo at the top of this page, they're costing you. The first clean takes the build-up off, and after that yearly maintenance keeps it off, at a lower rate.

Related

• How often to clean
• Inspection and thermal imaging
• Reviews