Using correct methodology to model solar glare
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The importance of correct methodology when modelling solar glare impact

The importance of correct methodology when modelling solar glare impact
October 1, 2014 Amy Sudbury

A large photovoltaic array, planned in the UK, has been advised on how to proceed by an airport, after the methodology used to conduct a Solar Glare Hazard Assessment was incorrect.

Solar Glare Methodology - Sun Position

The 60 acre solar development proposed on land at Flanchford Farm in Surrey. As considered best practice, the applicants consulted a number of stakeholders as part of the planning process.

One of the consultees was London Gatwick Airport (LGA).

“no evidence to suggest potential aviation issues have been considered”

Within the first response, the LGA safeguarding officer quoted the December 2010 Civil Aviation Authority (CAA) interim guidance. The officer also stated that “there was no evidence to suggest that any potential aviation issues have been considered.”

The CAA interim guidance advises developers that they should deliver documentation regarding the potential impact on aviation interests. Specifically for solar developments, the possibility of personnel being affected by glint and glare is a concern for aviation stakeholders. So are adverse impacts on radar equipment.

For the Reigate development, the LGA aerodrome safeguarding officer requested that the application be put on hold until glint and glare impact had been assessed.

Direction was given to use a free tool to carry out the request.

Solar glare hazard assessment submitted

Three days after the response from the LGA safeguarding officer, the free tool was used to run assessments to determine if, and when, glint and glare could occur for two flight paths crossing the entire site.

The results showed that there would be no issue with glare.

The assessments were submitted as supporting documentation, and the safeguarding officer came back with another response and recommendation.

“…methodology used is incorrect”

The response confirmed that the results of the assessments were right, however the methodology used when carrying them out was incorrect. This was because the flight paths used, did not “originate at the runway landing thresholds.”

The safeguarding officer went on to list the locations where the glare impact should be assessed, and suggest a best course of action forward for the developer. This included withdrawing the incorrect assessments and submitting an addendum which has been checked by the airport.

What can be learnt?

  • Not considering the impact of your solar development on aviation issues, can cause delays when in planning.
  • As well, accurately determining the impact of glint and glare effects on aviation interests is complicated. This is, in part, due to the number of locations that need to be included in the assessment.

In the case of the Reigate solar farm, the incorrect methodology used in the assessment yielded correct results.  However, this may not always be the case. If you have limited involvement in conducting glint and glare assessments, it can be worthwhile getting someone with experience to carry them out on your behalf.


Image accreditation: Vintro alvenas – 12 horoj kun la suno” by Alexandre André / CCBY / Cropped and resized from original.


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