Commercial rooftop arrays lose output as soiling accumulates — pollen, dust, bird droppings, and pollution film. In the Philadelphia region, the spring pollen load from oak and pine is heavy enough to measurably reduce output on any array with tree exposure. Bird droppings are the worst single offender because they are opaque and localized, and a shaded cell drags down the entire string it sits in.
We clean commercial arrays at low pressure without anyone walking the roof: a tap-water rinse, a soap wash, then a deionized final rinse that takes the soap off. No abrasive contact, and no mineral spotting when it dries. For large rooftop arrays, drone delivery covers the full surface without the access constraints of ground-based equipment.
Why we finish with deionized water
Tap water in this area carries dissolved minerals. Spray it on hot panel glass and let it dry, and you trade organic soiling for mineral spotting. So tap water and soap do the cleaning, and deionized water does the last rinse. It has the minerals stripped out, so it dries without residue.
Soap left on the glass dries to a film that pollen and dust stick to faster than clean glass, so the deionized rinse takes all of it off. Abrasives damage the anti-reflective coating permanently.
Signs it's time to schedule
- Visible pollen film or dust haze on the glass
- Bird droppings on the array surface
- Monitoring showing lower output than the same period last year
- Array under or adjacent to mature trees
- No cleaning since installation or last major service
- Leaf litter caught at the lower edge of panels
How we do it
Array and output review
We review the array layout, tilt, and your monitoring data. If output is down for a reason cleaning won't fix, we tell you before taking the job.
Debris clearing
Loose debris cleared from panel edges and the gap beneath the array before water is applied.
Rinse, wash, and final rinse
Tap water at low pressure, then a soap wash, then a deionized final rinse that takes the soap off. No abrasive contact, no roof traffic.
Output check
We ask you to check monitoring output in the days following cleaning so you have a before-and-after comparison.
Where we work
WashLabs is based in Philadelphia and serves commercial properties across Pennsylvania, New Jersey, and Delaware. We travel for the right job — if you have a property outside our immediate area, reach out and we'll let you know if we can make it work.
Commercial Solar Panel Cleaning questions
How much production will cleaning recover?
It depends on how soiled the array is. A lightly dusty array in open sun recovers very little. An array with a full spring pollen load and bird droppings is a different conversation. Check your monitoring against the same period last year before booking.
Will cleaning void our solar warranty?
Low pressure, no abrasive contact, and no foot traffic on the modules protect the panels. Send us your installer's maintenance guidance, including which soaps it allows, and we'll work to it.
How often should a commercial array be cleaned?
Once a year for most commercial arrays in southeastern Pennsylvania, timed for late spring after the oak and pine pollen has finished. Arrays with heavy tree exposure or a recurring bird problem do better on a twice-yearly schedule.
Do you serve arrays in NJ and DE?
Yes. We serve commercial solar installations across Pennsylvania, New Jersey, and Delaware.