Cleaning solar panels on flat roofs and raised frames

Why panels in Malta sit on frames

Pitched tiled roofs are rare in Malta and Gozo. Almost every house, townhouse and apartment block has a flat concrete roof, often shared with water tanks, a washroom, satellite dishes and washing lines. Panels laid flat on that surface would collect water and dirt and would not face the sun at a useful angle.

So most systems use raised metal frames: rails that hold the panels at a tilt facing roughly south. The frame:

• gives the panels a better angle to the sun,
• lets rain run off rather than pooling,
• keeps air moving underneath, which helps in summer heat,
• keeps the panels above the roof membrane, which can then be maintained.

That is good for output, but it changes how the panels get dirty and how they can be cleaned.

How frames change the way panels get dirty

• Dirt gathers along the bottom edge. Water runs down the tilted glass and stops at the lower frame, leaving a line of mud as it dries. This is the classic Maltese solar stain, worse after red rain.
• The top edge is high. On taller frames the upper row can be well above head height, so dust and droppings there are easy to miss.
• Underneath becomes a shelter. The gap between panels and roof is shaded and protected, which pigeons love. Nests, feathers and droppings build up, and birds perching on the top edge foul the glass below. See bird droppings on solar panels.
• Wind-blown rubbish gets trapped. Plastic bags, leaves and dust collect against the rails and can end up in the roof drains.

Access and safety

This is where flat roofs catch people out. A flat roof feels safe, but:

• Parapets are often low. Many older roofs have a short wall or none at all on some sides. Stepping back to look at a panel can put you closer to the edge than you think.
• Access may be through a washroom or a narrow hatch, which makes carrying water and equipment awkward.
• Roof surfaces can be slippery when wet, especially with soapy water on a smooth membrane.
• Panels and frames are not walkways. Never stand, kneel or lean on panels or rails. Glass cracks under point loads, and cracks you cannot see can still hurt output.

If you clean yourself, work from the roof surface with a soft brush on an extension pole, keep well back from unprotected edges and do not do it alone. Our guide on whether you can clean solar panels yourself covers the safe way, and when to hand it over.

Tools and method

Panels on frames are best cleaned with:

• Purified water, so the glass dries without mineral spots. Malta’s tap water is hard and leaves white marks.
• A soft brush on a pole, fed with water, so the upper rows can be reached from the roof.
• No pressure washer, no abrasive pads, no strong chemicals. These can damage the glass coating or seals. See does cleaning solar panels void the warranty.
• Cool times of day, early morning or late afternoon.

How often

Frame-mounted panels on a Maltese roof usually need cleaning once or twice a year: after the summer, in September or October, and again in spring. Homes near the sea, building sites or busy roads, and roofs with pigeons, may need more. Our guide on the best time of year to clean solar panels explains the timing.

Shared roofs with several systems

On apartment blocks, the roof may hold panels from several flats, sometimes installed by different companies at different times. That raises practical questions:

• Whose panels are whose? Strings are not always labelled. Before anyone cleans, owners should know which panels are theirs, so nobody touches someone else’s system.
• Who pays and who books? Some blocks arrange one clean for everyone, which is quicker and easier to plan. Others leave it to each owner. Agree it with the other residents or the block administrator.
• Access and keys. The cleaner needs safe access to the roof and to know where the tanks, washroom and any fragile surfaces are.

For blocks, one visit that covers every system on the roof usually works best. If you manage a block or are the one who organises things, ask us for a quote for the whole roof.

While you are up there

A clean is a good chance to check the roof around the panels:

• clear rubbish and leaves from under the frames,
• check the roof drains are not blocked before winter (see looking after a flat roof in Malta),
• note any loose cabling, rust on the frame or damaged panels for your installer.

We do not repair panels, wiring or frames. If anything looks wrong, the installer is the right person to call.

Booking

We arrange solar panel cleaning on flat roofs and raised frames across Malta and Gozo, for single homes and for whole apartment-block roofs.