The current operational capacity of solar photovoltaic (PV) developments in the UK is just over 9,000 MW , which doesn’t include the further 4,000 MW with planning permission, awaiting construction or under construction . Solar developments can be of concern to aviation stakeholders due to the potential for dazzle or ‘glint and glare’ effects from the solar panels.
Military air bases and civil airports are important stakeholders on a national level whilst local airfields may be important for the local economy. In all instances, concerns raised by an aviation stakeholder where safety is cited as a risk will always have the potential to stop a solar development from obtaining permission if they are not comprehensively addressed.
The following article presents an overview of the potential impact of solar PV developments on three aspects of aviation activity. This includes an example where each issue has been encountered and the steps that were taken to overcome the concern.
Why is Glint and Glare an issue for airports?
Solar reflections off of the PV panels could cause a distraction to pilots. This can be considered a hazard by airport operators, particularly if effects are possible at critical stages of flight. An application for a solar development in Belton  was refused permission by North Lincolnshire Council in July 2014; one of the reasons was an outstanding Glint and Glare concern from Doncaster Sheffield Robin Hood airport.
Pager Power Case Study
As an example, Pager Power worked with AAH Planning and Barrow/Walney Island Airport to overcome an objection pertaining to a proposed nearby solar development called Sowerby Lodge. The key concerns were the effects of glint and glare on aircraft approaching and departing the airfield as well as aircraft flying parts of the visual circuit.
Following technical analysis, which involved geometrical and operational assessment, consultation and a meeting, the airport’s objection was removed and planning consent was received.
Air Traffic Controller distraction
An additional concern facing developments in the UK is the potential for glint and glare impacts on the airport’s Air Traffic Control tower. This could present a distraction to the air traffic controllers and cause a safety hazard. A solar development built at Manchester-Boston Regional Airport in the USA had to be covered up at certain times of the day after construction because of glint and glare affecting the air traffic controllers in the morning .
Pager Power Case Study
In early 2015, Bristol Airport completed construction of their new terminal building. On the roof of the terminal an array of solar PV panels was proposed however there were concerns regarding solar reflections towards the ATC tower, which was just over 300m west of the terminal building.
Pager Power was engaged to assess and understand the effects of glint and glare on the ATC tower. With the ATC Tower having partial views of the rooftop, it was important to determine whether
- Glare could occur towards the ATC Tower
- If any glare would prove to be a significant hazard to aviation safety.
Subsequent to the report, the risk was assessed and deemed acceptable. The rooftop PV panels were then installed and have now been producing electricity since summer 2015. More information can be found here.
Interference to airport equipment
Another concern – which is far less common – is the potential for interference to radar and other equipment at an airport.
Such objections can relate to the physical structure of the solar panels or the potential for radio interference between the electronic equipment. These issues require bespoke consideration based on the scale and location of the development.
Pager Power Case Study
This was a particular concern of Robin Hood Airport Doncaster Sheffield for a proposed solar development approximately 19km north west of the airport. Pager Power’s bespoke radio line of sight analysis tool was used to determine whether the radar would have a significant view of the solar panels. Further additional shielding analysis was also undertaken to determine whether any above ground obstructions existed. The report findings were positive and the objection was subsequently removed. The solar farm is now consented and operational.
How to deal with Glint and Glare issues
To avoid unnecessary project delays, it is advisable to investigate the potential for glint and glare issues before an application is submitted. Effects can be predictably modelled because:
- Solar panels are flat with a known position and orientation.
- The motion of the sun across the sky can be modelled with high accuracy.
- This means the location and time of a reflection can be accurately calculated.
By determining where and when reflections will occur, the severity of any issues can be assessed and any necessary mitigation can be determined.
What is Glint and Glare?
Solar panels are designed to absorb as much sunlight as possible and convert this into electricity. However, a small percentage of the sunlight will be reflected by the solar panel. This reflected portion of the light can reach an observer’s eye and cause a distraction or a disturbance. These reflections are known as Glint and Glare. Specifically, Glint is a momentary flash of light and Glare is a more continuous source of light.
Does anti-reflective coating resolve this issue?
Modern solar panels often contain anti-reflective surfaces, which reduce the effects but do not eliminate them completely. The issue remains a concern for planning applications in the UK.
Solar developments in the UK can and do receive objections from military and civil airports. Such objections can stop applications from receiving permission. Failure to address the issues can lead to impacts at the operational stage of a development. The issues are well understood and can be comprehensively assessed at the pre-application stage. Early engagement and assessment can be the difference between permission and refusal.
Editors Note: This post was first published on 18th July 2014, but has been updated for accuracy and comprehensiveness.
 Renewable energy planning database monthly extract, Department of Energy & Climate Change, last updated 16th February, 2016. (Last accessed 11/03/2016)