Are solar farms really a hazard to drivers?

What is the concern?

The concerns relate specifically to the possibility of solar reflections from a solar farm (in the form of Glint and Glare) potentially creating a safety hazard to drivers on surrounding roads. Whilst the magnitude of these reflections are comparable to water and glass, many of which are encountered by a road user on a regular basis, the addition of these reflective surfaces in the ambient environment can require assessment to determine whether the reflections can be viewed, and if so where and when they will occur.

Are solar glare reflections a safety hazard?

In the majority of cases the solar reflections are not deemed a hazard to road safety. This is because either the solar farm is not significantly visible from a surrounding road or if it is, the solar farm is not located where reflections will be orientated towards the road. In many instances, however, the Highway Agency or Local Planning Authority (LPA) will consider the possibility of any effects before making a decision.

In what locations are road concerns most likely to arise?

If your solar farm is surrounded by a public road then the Highway Agency or LPA may request an assessment, however assessments are most likely to be required when the solar farm is to be sited beside “A” roads and motorways where high volumes of traffic are most common. Interestingly, ground based reflections are most likely to occur in the morning and in the late afternoon/early evening. At these times, roads are likely to be busiest and therefore ensuring safety is paramount.

Have there been cases where a solar farm has been proposed and a road safety concern has arisen?

Yes, three examples are listed below:

1. A solar farm was proposed to be sited alongside a busy road in the south west of Wales and, following consultation with the local Highway planning agency, a concern was raised regarding the potential for direct solar reflections to potentially cause a hazard to drivers [1].
2. Residents in a small hamlet near Waderbridge, north Cornwall, have voiced concerns for a proposed solar farm, with one of the issues cited being the possible impact upon road safety on the A39 when travelling west into the setting sun (when reflections from the solar panels could occur) [2].
3. Local Residents are concerned about the effect of 41,500 solar panels to be installed in Danbury near Chelmsford, Essex. Particular concerns are regarding the effects of Glint and Glare on a surrounding single-track road, which local children use to walk to a bus stop [3].

There are many more examples throughout the UK.

Have there been cases where a solar farm has been built and subsequently a hazard has arisen?

There are cases in the UK where concerns and complaints have been received post construction. For example, a newly erected solar farm near Whitland in Carmarthenshire, south west Wales, has received complaints regarding the impact of glare upon local roads. At certain times of the day, the sun is in a position to produce glare towards a local road. Though no accidents have been caused by the glare[4], local residents are concerned regarding the additional safety risk [5].

What can be done to mitigate any effects?

The first option available to a solar developer is to install screening between the road and the solar farm. It is important to remember that if the solar farm cannot be seen then there is no possibility of a reflection being experienced. If this is not possible then it may be possible to remove or cover the panels that could create reflection. Read more about glint and glare mitigation here.

So what should you do next?

If you are looking to site a solar farm next to a road, then it is worth considering the potential safety implications. Even if the Highway Agency or the LPA do not request an assessment, local residents may voice concern and, therefore, undertaking a road based glint and glare assessment is likely to be beneficial to your planning application.

Has Pager Power worked on projects where the effect of glint and glare has been assessed with respect to road safety?

Pager Power has completed many glint and glare assessments pertaining to the possible impact upon road safety, in fact it is something we recommend for all solar developments where a road is located nearby.

One particular example where the impact upon road safety was explicitly raised by the Highways Agency was the now consented solar photovoltaic (PV) farm to be located on land north of Gonerby Lane, Allington in Lincolnshire, England. The solar farm will consist of 22,000 solar panels located on 11 hectares of land adjacent to a trunk road leading to the A1 dual carriageway. Glint and glare was identified as a possible risk by the Highways Agency due to its location next to a busy road and requested that glint and glare effects be investigated.

Pager Power was contacted and subsequently commissioned to complete a glint and glare assessment with a site survey. The geometric analysis was completed to determine whether solar reflections were geometrically possible towards the road and at what time they would occur. The survey was completed to accurately assess ground heights using an advanced GPS unit at the solar farm and road receptor locations, and to better understand the visibility between the two. The results of both pieces of work were collated to produce a report detailing the overall expected impact of the proposed solar farm.

The results of the analysis showed that whilst solar glare reflections were possible, the likely impact to road safety would not be significant. The report was submitted to the Highways Agency who stated:

‘In light of the glint and glare assessment provided we are content that the proposed development is not expected to have any material impact on the closest strategic route, the A1. Therefore…, the Highways Agency has no objection to the proposal…’.

Editors Note: This post was first published on 27^th August 2014, but has since been updated for accuracy and comprehensiveness.

References

[1] Removal of concerns raised by Highway Agency about direct reflections from a proposed solar farm – https://www.pagerpower.com/pages/case-studies/successes-of-2013.php

[2] Fears over impact of huge solar farm, This is Cornwall, West Briton, 2011 – http://www.westbriton.co.uk/Fears-impact-huge-solar-farm/story-11429086-detail/story.html

[3] Fears over plan for solar farm, Chelmsford Weekly News, 2013 – http://www.chelmsfordweeklynews.co.uk/news/10642472.Fears_over_plan_for_solar_farm

[4] At the time of writing – August 2014.

[5] Concern over solar park glare ‘danger’, Carmethan Journal, 2014 – http://www.carmarthenjournal.co.uk/Concern-solar-park-glare-8216-danger-8217/story-20964851-detail/story.html

Image accreditation: “HA0484-035″ by Highways Agency /CC BY / cropped and resized from original.