Bird-proofing solar panels

An on-roof array creates a sheltered cavity between the panels and the tiles, and pigeons treat it as excellent nesting habitat. Once they are established, the consequences are droppings down the roof and walls, nesting material blocking gutters and downpipes, debris trapped under the array restricting airflow, damage to cable and connectors from pecking and nesting, noise directly above bedrooms, and mites. The fix is a physical barrier: a mesh fitted around the perimeter of the array using clips that attach to the panel frames, closing the gap without penetrating the roof or the panels.

Why it happens

The gap exists for good reasons — airflow behind the panels keeps cell temperatures down, and the mounting system needs clearance. But from a pigeon’s point of view it is a warm, dry, covered ledge, elevated away from cats and foxes, with open sides for access.

Terraces and semis in established residential areas see it most. So do properties near existing pigeon populations, near feeding sources, or where neighbouring roofs already have colonies.

In-roof arrays largely avoid the problem, because there is no cavity to occupy. That is one of the quieter arguments in favour of in-roof mounting on properties in known pigeon areas.

What the damage actually is

Soiling. Droppings are acidic and persistent. On the glass they shade cells directly; on the roof and walls they stain and, over time, attack mortar and paint.

Gutter and drainage blockage. Nesting material and feathers wash into gutters and hoppers. Blocked gutters overflow, and overflowing gutters cause damp problems at the wall head.

Restricted airflow. Debris packed under the array reduces the ventilation the design relied on.

Cable and connector damage. Birds peck at cable insulation and nesting material abrades it. DC cabling under an array is not something you want disturbed.

Roof covering damage. Persistent activity dislodges tiles and disturbs mortar.

Mites and noise. Bird mites migrate into loft spaces. And the noise, directly above a bedroom ceiling, is the reason most people finally call.

How proofing is fitted properly

The principle is simple: close the perimeter gap with a physical barrier that does not compromise the roof, the panels or the ventilation.

• Mesh. A galvanised or PVC-coated steel mesh with an aperture small enough to exclude pigeons, in a specification that will not corrode over the life of the array. Plastic netting is not adequate.
• Frame clips. Stainless clips that grip the panel frame and hold the mesh. Nothing is drilled through a panel, a frame or a roof tile.
• Full perimeter. Every open edge is closed. Birds find a single unclosed section quickly, and a partially proofed array is an unproofed array.
• Ventilation preserved. Mesh excludes birds while leaving airflow behind the panels essentially unaffected.
• Clean first. Existing nests, debris and droppings are cleared before the mesh goes on, and the array and roof are cleaned. Sealing debris in defeats the purpose.

Fixings driven into the roof covering, cable ties as a permanent solution, and anything penetrating a panel frame are all signs of a job done badly. Panel manufacturers are specific about what may be attached to a frame, and warranty exclusions follow from ignoring it.

The legal position

Wild birds are protected in the UK. In broad terms it is an offence to intentionally kill or injure a wild bird, or to take, damage or destroy a nest while it is in use or being built, or to destroy eggs. There are limited exceptions under general licences, but they are narrow and conditional.

The practical consequences for proofing work are straightforward. An active nest cannot simply be removed. Mesh cannot be fitted in a way that traps birds inside the cavity. Work therefore has to be planned around nesting activity, and a competent contractor will inspect before proofing rather than sealing first and looking afterwards.

Where there is an active nest, the options are to wait until the young have fledged, or to involve a licensed pest controller who can advise on what is lawful in the specific circumstances.

Timing and access

Proofing is roof work, so it needs the same access arrangements as an installation — usually a scaffold or an appropriate work platform.

That has a useful implication. If you are having an array installed, or having scaffolding up for any other reason, fitting proofing at the same time costs a fraction of doing it as a separate visit later. On properties where pigeons are already visible on neighbouring roofs, it is a sensible piece of preventive work rather than a repair.

Afterwards

Proofing is not a one-off that never needs looking at again. Clips can loosen, mesh can be damaged by falling branches, and a section disturbed by other roof work creates an opening.

Include a look at the mesh in any periodic inspection of the array, and deal with a small gap promptly. Once a colony re-establishes, you are back to cleaning as well as proofing.