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When panels need cleaning
The Energy Saving Trust says that in the UK, rain will keep panels clean if they are tilted at 15 degrees or more, and that dirt is more likely to build up on ground-mounted panels or in dusty areas (Energy Saving Trust). Most pitched roofs are steeper than that, so plenty of panels never need a professional clean.
Where cleaning does help is with bird droppings, which rain doesn’t shift and which can shade individual cells, with moss and lichen at the lower edge of the panels, and with panels on flat or shallow roofs. Homes near busy roads can also build up a film of grime.
How we clean
We use purified water with soft brushes on extending poles, working from the ground where possible or from safe access at the roof edge. Purified water dries without leaving marks. We don’t use detergents, abrasive pads or pressure washers, which can damage the panel surface and affect the maker’s warranty.
While we are there, we look over the panels for cracks, scorch marks and signs of pigeons underneath. Anything we find goes in the short report you get afterwards.
What it costs
Checkatrade’s guide for Derby is about £15 a panel, or £60 to £100 to clean around 40 panels at ground level and £150 to £300 above one storey (Checkatrade). The Energy Saving Trust says the average home system uses around 12 panels, so the real cost is usually well below those totals. You get a fixed price before the visit.
Pigeons and cleaning
If pigeons are the reason the panels are dirty, cleaning alone won’t last. Mesh around the edge of the array stops them getting underneath. See solar panel bird proofing, and pigeons under solar panels for what the law allows when nests are in use.
What's included
- A look at the panels before cleaning to note any damage
- Pure-water cleaning with soft brushes
- Removal of bird droppings, lichen and moss from the panel surface
- Clearing debris from the edges of the array where reachable
- Generation reading noted before and after where the weather allows
- Any cracks or hot spots reported
- Advice on how often your panels are likely to need it
- A written price before the visit
How the options compare
Safety
- Leave it
- n/a
- Hose and brush yourself
- Ladder work at height
- Professional clean
- Done from the ground or with proper access
Risk to panels
- Leave it
- Dirt builds up
- Hose and brush yourself
- Detergents or scratching can damage coatings
- Professional clean
- Pure water and soft brushes
Stubborn dirt
- Leave it
- Stays
- Hose and brush yourself
- Hard to shift
- Professional clean
- Removed
Damage spotted
- Leave it
- No
- Hose and brush yourself
- Rarely
- Professional clean
- Reported
