Should you clean your own panels?
It depends almost entirely on where the array is. A row of panels on a garden frame, a low garage roof or a ground-mounted rack is within reach for most people, and a gentle rinse a couple of times a year does no harm. Panels on the main roof of a two-storey house are a different matter. The cleaning itself is simple; getting to the glass without risk to yourself, the tiles or the wiring is the difficult part.
Before doing anything, find the paperwork that came with the system. Installers and panel makers often give their own care instructions, and those should always take priority over general advice, including the advice on this page. If you cannot find any, ask the company that fitted the array what they recommend.
Safety first: roofs, ladders and electrics
A wet roof is slippery, and panel glass is even more so. Leaning a ladder against a gutter to reach a roof array puts your weight on the weakest part of the roofline and leaves you stretching sideways with water and a brush. Most falls during home maintenance happen in exactly this kind of situation, so if reaching the panels means climbing, stop there.
Panels generate electricity whenever light reaches them, and you cannot switch the glass off. Never clean a panel that is cracked, has damaged cabling showing or has scorch marks on the frame. Keep water away from junction boxes and the inverter, and never stand on a panel or rest a ladder against one.
What to use: soft brushes and clean water
The professional method used by OOR External is deliberately plain: soft brushes and clean water, so nothing scratches the glass or attacks the seals around the frame. At home, the equivalent is a soft bristle brush or sponge and a hose on a gentle spray. Work from the top of each panel downwards so loosened dirt runs off rather than across the area you have already done.
If your tap water is hard, it can leave faint white spots as it dries. A final rinse with softer water, or simply cleaning on an overcast day so the glass dries slowly, helps avoid that.
- Soft bristle brush or non-scratch sponge
- Gentle hose spray, never a jet
- Clean water with nothing added unless your installer approves it
- A cool, overcast day or early morning
What never to use on the glass
Most damage to panels during cleaning comes from good intentions. Abrasive pads, scouring powders and stiff brushes leave fine scratches that hold dirt and scatter light. Household detergents and glass cleaners can leave a residue that attracts dust and may affect the anti-reflective coating some panels carry. Pressure washers are the worst option of all, because a concentrated jet can force water past the frame seals and into places it should never reach.
- Pressure washers or jet nozzles
- Scouring pads, wire wool or stiff brushes
- Washing-up liquid, bleach or glass cleaner
- Scrapers or blades on dried deposits
Ground-floor and garden-mounted arrays
Panels on a garden frame, carport or outbuilding are the ones a homeowner can usually look after. Check them after a dry, dusty spell or once the trees have dropped their pollen, and look along the lower edge where dirt tends to collect as rain runs down and dries. A light rinse there often makes more difference than cleaning the whole face.
Bird droppings, lichen and salt film
Droppings are the most common problem, and they bake hard in summer sun. Soak them with clean water and give the water a few minutes to soften the deposit before brushing gently. Never pick at them with a blade. Lichen tends to grip the lower frame edge and is slow to shift with water alone, which is usually the point where a professional clean is worthwhile. Near the Kent coast, a dull grey salt film builds up across the glass and rinses away fairly easily with clean water.
When to book a professional clean
Book a professional when the array is on a roof you would have to climb, when deposits will not shift with water, or when the panels are part of a larger roof that also needs attention. OOR External cleans domestic and commercial arrays, often from ground level with reach equipment, and can combine the work with roof moss removal or gutter clearance in the same visit. If a lower pressure approach is mentioned for the surrounding roof or walls, the separate guide on soft washing safety explains what that involves.