How often should you clean solar panels in New Jersey?

A New Jersey roof gives a solar array plenty to deal with: tree pollen in April, bird droppings through the summer, leaf litter in October, and snow, ice and road salt in January. The question we hear most is simply how often the glass should be washed.

There is no single number that fits every home, but the pattern is consistent. Panels in open, rural or wooded lots need more attention than panels on a clear suburban roof, and a single stubborn stain can cost more production than a light film of dust.

The short answer: once or twice a year

For most homes in Monmouth, Middlesex and Ocean counties, two cleanings a year keeps an array close to its rated output: one in late spring after the pollen season has finished, and one in late autumn after the leaves are down.

If your roof is surrounded by mature trees or sits near a busy road, a spring clean, a mid-summer rinse and an autumn clean is often worth it. If your array is on an open, south-facing roof with nothing above it, an annual visit may be enough.

Why a little dirt is more expensive than it looks

Soiling rarely fails a system outright. What it does is quietly reduce output every sunny hour, which shows up on your bill rather than on the roof.

• Pollen creates a sticky film that rain does not fully rinse away.
• Bird droppings shade a single cell, and because cells are wired in series, one shaded cell can pull down the output of a whole panel string.
• Leaf litter and pine needles collect along the bottom rail of the array and hold moisture against the frame.
• Snow and ice left sitting for weeks keep production at zero and stress the mounting hardware.

Signs your array is overdue

You do not need to climb up to check. Watch your monitoring app instead. A drop of more than about 10 percent against the same month last year, with no change in weather, is the usual signal. Visible streaks, white spotting along the lower edge of the glass, or a dark patch that does not wash off in the rain are all reasons to book a visit.

What not to do

Do not pressure-wash panels, and do not use dish soap or abrasive pads on the glass. High pressure can force water behind the frame, and harsh soaps leave a residue that attracts more dust. Panels are cleaned with deionised water and a soft brush, ideally in the morning while the glass is cool.

If you would rather not think about the schedule at all, a routine cleaning visit once or twice a year is the simplest way to keep production where it should be. We price it up front for your roof, and you pick the arrival window.