Solar Panel Cleaning

Commercial Solar Panel Cleaning by Rope Access

A rooftop array earns its money by the square metre, and every square metre of glass that is dirty is a square metre that is not working. On a domestic roof that is a rounding error. On a commercial roof carrying several hundred panels it is a line on the electricity bill, every month, quietly.

We clean commercial and industrial arrays on roofs that are difficult or unsafe to reach: fragile profiled sheet, steep pitches, roofs with no plant access, and arrays that run to the ridge with nowhere to stand.

What dirt actually costs you

We are not going to quote you a percentage, because anyone who does is guessing. Soiling losses depend on pitch, local dust, tree cover, bird traffic, industry and how long it has been. A shallow-pitched panel next to a farm track and a steep panel in clean air are different problems.

What does hold true everywhere is how the loss happens:

• Shading is not proportional. A panel is a chain of cells wired in series. One heavily soiled cell throttles the current through its whole string, so a small area of dirt costs more than its own surface area.
• Edge deposits are the worst kind. Rain washes the middle of a panel and leaves a band of silt and moss along the bottom frame, exactly where it shades a full row of cells.
• Bird droppings are opaque. Unlike dust they do not thin out with rain, and they bake on.
• Rain is not a cleaner. It moves dust around and evaporates, leaving the dissolved solids behind. This is why an array can look washed and still be soiled.

If your inverter or monitoring platform logs per-string output, you already own the only honest measurement of what soiling is costing you on your roof. We are happy to work from that data rather than a brochure number.

The hard part is the roof, not the glass

Cleaning glass is simple. Reaching several hundred panels on an industrial roof without damaging the roof, the panels or a person is not.

• You cannot walk on panels. Standing on a module can cause microcracks in the cells that are invisible on the day and permanent afterwards.
• Profiled sheet and rooflights are fragile. Falls through fragile roof materials are one of the most common causes of death in UK construction, and a weathered rooflight can look identical to the sheet beside it.
• A cherry picker rarely reaches mid-roof. Even where there is hardstanding for one, it will not span an array that runs to the ridge.
• The array itself blocks the walkways. Panels are usually laid to fill the roof, which removes the safe route across it.

How we do it

1. Access assessed first. Anchor points, roof construction, fragile areas and rooflights identified before anyone steps on the roof.
2. Work from the ridge and safe zones. Operatives are attached throughout, and reach the array with telescopic water-fed poles instead of standing on it.
3. Deionised water, no detergent. Pure water lifts the soiling and dries without leaving the residue that ordinary water leaves behind, so there is nothing left to attract more dirt.
4. No pressure washing, no abrasives. High pressure drives water past the frame seals and can void the panel warranty. Soft brush and pure water only.
5. Defects reported as we go. Cracked glass, discoloured cells, delamination, loose clamps, chafed cabling, vegetation and blocked gutters, all photographed.

How often

Once a year suits most commercial roofs. Twice makes sense where the array sits near trees, a farm, a busy road, a food or industrial process, or a gull population. The right answer for your site is visible in your own generation data.

Related services

• Gutter cleaning and blockage removal
• Roof surveys and condition reports
• Green roof maintenance
• Bird netting installation

Questions we get asked about solar cleaning

Will cleaning void my panel warranty? Not the way we do it. Warranties are voided by high pressure, abrasives and detergents, which is why we use a soft brush and deionised water only.

Do you need a cherry picker or scaffold? Usually not. We work from the ridge and safe zones on ropes, which is what makes a mid-roof array reachable at all.

Do you walk on the panels? Never. Standing on a module can cause microcracks that are invisible on the day and permanent afterwards. We reach across the array with water-fed poles.

Do you work outside London? Yes. We cover Hertfordshire and the home counties as well as London. A site visit is free of charge within London; outside London a technical assessment is chargeable and credited against the works if you proceed.