One of the first stages of determining the impact of glint and glare is whether a solar reflection is experienced by an observer. This involves undertaking a review of the available imagery, topography, landscaping strategy, and site photography is to determine whether the reflecting panels are significantly screened.
In this article, we provide an overview of what is considered as ‘significant’ screening that allows us to determine the impact significance.
Significant Screening Explained
You’d be forgiven for thinking that significant screening resulting in no impact simply means that the screening must be opaque such that the reflecting panels are completely obstructed. Whilst this is the best case, and the easiest to judge when reviewing the imagery, Pager Power’s glint and glare guidance document provides allowance for dense screening, where there are insignificant gaps, to be considered significant screening.
The following excerpt has been taken from Pager Power’s glint and glare guidance document (find the full glint and glare guidance here):
‘Significant screening’ with respect to visibility of reflecting solar panels implies that the observer’s view is impeded to the extent that the presence of the solar panels cannot be easily discerned at first glance. For example, a hedgerow that contains small gaps that facilitate partial visibility of the panel face(s) would provide ‘significant screening’. Figure 11 on the following page [below in this article] illustrates this.
Figure 1: Illustration of ‘significant screening’.
As per the excerpt from the glint and glare guidance, significant screening implies that the observer’s view is impeded to the extent that the presence of the solar panels cannot be easily discerned at first glance.
This description is pertinent for glint and glare because solar reflections viewed through these small gaps will not be experienced as specular (mirror-like) reflections and will instead be experienced as diffuse (scattered) reflections, which are not predicted to cause any impacts to safety or amenity.
Significant Screening Example
Gaps in screening typically come from vegetation during the winter months when not in leaf. In many cases, the lack of leaves would mean that views are no longer significantly obstructed; however, in some cases, the density of the vegetation is such that significant screening is still present. The most important consideration is that the screening provides sufficient screening at the times of the year in which solar reflection are predicted.
An example of significant screening, where only very minor views of a proposed development would be possible, is shown in Figure 1 below.
Figure 2: Significant screening example. [1]
In this example, Pager Power would deem the proposed development significantly screened and no glint and glare impacts would be predicted. It will then be recommended that the landscaping team ensures the vegetation is maintained to at least this density and height.
Conclusion
For a proposed development to be significantly screened in the context of glint and glare, the screening must be of sufficient density so that the presence of the solar panels cannot be easily discerned at first glance. In practice, this gives some allowance for some insignificant gaps. Overall, the necessary level of screening should remove effects such that the solar reflection cannot cause a significant impact to safety or amenity.
About Pager Power
Pager Power has undertaken more than 1,000 glint and glare assessments in the UK and overseas, with almost all including a review of available imagery and photography to determine the level of screening. If you require a glint and glare assessment for your development, please get in touch on +44 (0)1787 319001.
[1] Copyright: Google Earth 2023.
