Commercial solar near airports: glint, glare and safeguarding

The short answer

• Solar panels are designed to absorb light, so they reflect far less than glass or water, but they can still produce glint (a brief flash) and glare (a sustained bright reflection) at certain sun angles.
• Near an aerodrome, the concern is pilots on approach and controllers in the tower. Near a railway, it is train drivers and signals. Near a road, it is drivers.
• In England, systems above 50 kW need prior approval, which looks specifically at glare on neighbouring land, and the council consults the aerodrome operator on development inside its safeguarding area.
• In Scotland and Wales, the non-domestic rooftop permitted development rights do not apply within 3 km of an aerodrome or airport, so you need a planning application.
• A glint and glare study models where reflections fall through the year and is the usual way to show there is no problem.

Note: This guide is general information. Safeguarding rules, consultation zones and the evidence each aerodrome asks for vary. Contact the planning authority and, where relevant, the aerodrome operator early.

Glint and glare in plain terms

Glint is a momentary flash, for example as a driver passes. Glare is a reflection that lasts longer, for example a fixed point in a control tower window seeing the sun reflected off an array for some minutes each day at certain times of year. Whether either happens depends on:

• the tilt and orientation of the panels,
• the position of the sun through the day and the year,
• where the receptor is (a runway approach path, a tower, a signal, a road),
• what screens the view, such as buildings, trees and landforms.

Modern panels have anti-reflective coatings and textured glass, which reduce reflection. Flatter, low-tilt layouts on large roofs often send any reflection skywards rather than towards the ground.

Aerodrome safeguarding

Safeguarding is how aerodromes protect their flight paths and equipment from development nearby. In England, officially safeguarded aerodromes lodge safeguarding maps with local planning authorities, and the authority consults the aerodrome operator on development within the consultation area (GOV.UK: safeguarding aerodromes, technical sites and military explosives storage areas). The Ministry of Defence safeguards military aerodromes in the same way.

For solar, the aerodrome will usually ask whether the array could:

• produce glare for pilots on the final approach or during circuits,
• produce glare in the control tower,
• affect radar, navigation aids or instrument landing systems (rare for rooftop solar, but asked about for large ground arrays),
• attract birds, which matters for bird strike risk.

Smaller airfields and private strips may not be officially safeguarded, but it is still sensible, and good neighbourly practice, to talk to the operator.

The rules by nation

• England: rooftop solar on non-domestic buildings can use permitted development. For systems above 50 kW, the prior approval application asks the council to consider design, appearance and, in particular, the impact of glare on occupiers of neighbouring land. Safeguarding consultation applies to any planning application or prior approval inside a safeguarding area.
• Scotland: the non-domestic rooftop and free-standing solar rights do not apply within 3 km of an aerodrome (Scottish Government circular 2/2024).
• Wales: Welsh Government guidance excludes sites within 3 km of an airport or aerodrome from the non-domestic solar permitted development right (GOV.WALES).
• Northern Ireland: check the position with the district council and, near Belfast International, George Best Belfast City or City of Derry airports, with the airport.

Our planning permission guide covers the wider permitted development rules.

What a glint and glare study involves

A specialist models the array's geometry against the sun's path for every day of the year and identifies where reflections could reach. A typical study:

1. maps the receptors: runway approaches, the tower, nearby roads, railway lines and signals, and neighbouring homes,
2. models the panel tilt, orientation and height,
3. reports whether reflections reach each receptor, for how long and when, and how bright they would be,
4. recommends changes if needed, such as a different tilt, a different orientation or screening.

For many rooftop schemes the study simply confirms that reflections go upwards or are screened. Where they do not, small design changes usually solve it. The survey and design stage is the time to find out: see what the survey includes.

Railways and roads

Network Rail looks at whether glare could affect drivers' view of signals near the line, and highway authorities at whether it could distract drivers on fast roads or at junctions. Planning authorities may consult them on schemes alongside their networks. The same glare modelling answers both questions.

Practical tips

• Tell your installer early if the site is near an airport, airfield, railway or major road.
• Ask the planning authority whether the site is in an aerodrome safeguarding area.
• Budget for a glint and glare study on larger roofs and any ground-mounted array near these receptors.
• Keep the study with your planning documents; insurers and landlords sometimes ask for it.