This article provides an overview of the planning guidance in England relating to the Permitted Development (PD) of solar Photovoltaic (PV) projects, particularly commercial rooftop.
The available planning guidance for PD PV projects is presented and discussed, with reference to solar glint and glare, so that developers and planners can better understand the required steps to be taken when proposing a small – scale PV project.
Town and Country Planning – Solar PV panels
The latest issue of the Town and Country Planning, (General Permitted Development) (England) Order 2015 came into force on the 15th April 2015 . Permitted Development rights now extend to non-domestic rooftop solar PV developments of up to 1 megawatt. Previously it only existed for solar PV development up to 50 kilowatts (a twenty-fold increase in generative capacity that can be covered under PD rights).
Figure 1: A large solar PV rooftop development
Solar PV Panels and Permitted Development
Under English planning legislation, it is possible to install, alter or replace ‘other solar PV equipment on the roof of a building’ excluding ‘a dwellinghouse or a block of flats’. It is important to note that to obtain PD rights, the electrical capacity of the development must not exceed 1 megawatt.
In detail, the criteria states that PD rights are not permitted if:
- the solar PV equipment or solar thermal equipment would be installed on a pitched roof and would protrude more than 0.2 metres beyond the plane of the roof slope when measured from the perpendicular with the external surface of the roof slope;
- the solar PV equipment or solar thermal equipment would be installed on a flat roof, where the highest part of the solar PV equipment would be higher than 1 metre above the highest part of the roof (excluding any chimney);
- the solar PV equipment or solar thermal equipment would be installed within 1 metre of the external edge of that roof;
- in the case of a building on article 2(3)  land, the solar PV equipment or solar thermal equipment would be installed on a roof slope which fronts a highway;
- the solar PV equipment or solar thermal equipment would be installed on a site designated as a scheduled monument; or
- the solar PV equipment or solar thermal equipment would be installed on a listed building or on a building within the curtilage of a listed building.
The panels must be sited to minimise the effect on the appearance of the property and public amenity, as well as be removed once the solar panels are no long required.
Permitted Development, Solar PV Panels and Glint and Glare
The Town and Country Planning, (General Permitted Development) (England) Order 2015 also states that a written application from the developer to the local planning authority must be made before development has commenced .
Specifically it states:
‘development is permitted subject to the condition that before beginning the development the developer must apply to the local planning authority for a determination as to whether the prior approval of the authority will be required as to the design or external appearance of the development, in particular the impact of glare on occupiers of neighbouring land..’
The guidance specifically states the importance of determining the impact of glare upon ‘occupiers of neighbouring land’ when applying for PD rights.
The term ‘neighbouring land’, however, is not defined within the guidance nor is there a standard definition. The definition could therefore be defined on a case-by-case basis, for example:
- An adjacent dwelling with views of the PV panels would be considered to be on occupier of neighbouring land; or
- An airport 3km from the PV panels with approach paths leading over the PV panels could be considered to be an occupier of neighbouring land; or
- A railway line running alongside a commercial property with a view of the PV panels could also be considered to be on an occupier of neighbouring land.
Therefore, ‘occupiers of neighbouring land’ could be considered to mean receptors where glare could cause a significant effect, however this will only ever be if visual line of sight to the PV panels exists.
What is Glint and Glare?
When sunlight illuminates an object, an amount of the incident light is reflected. This reflected light, when directed towards an observer, can become noticeable and cause a distraction or nuisance.
The unwanted reflection of sunlight is referred to as ‘glint’ (a momentary flash of bright light) or ‘glare’ (a continuous source of bright light). Where reflected sunlight may be visible to a receptor i.e. a nearby dwelling or a road user, it can be concluded that glint and glare effects are possible.
The effects of glint and glare can vary. In some circumstances, the effects may be negligible and no more significant than the many sources of solar reflection we experience on a day-to-day basis e.g. a fleeting solar reflection off a passing car. However, it is possible that the effects can be more significant which may lead to a detrimental impact to residential amenity or road safety.
How do you Assess Glint and Glare?
Glint and glare from solar PV is assessed via a geometric analysis that considers the location, orientation and angle of each panel relative to a surrounding receptor location e.g. a dwelling, and the path of the Sun as it passes over the sky over a year.
The results of the modelling show whether a solar reflection from the PV panels is geometrically possible, and if so the time and duration for which the solar reflection will be experienced. More about our glint and glare modelling charts can be found here.
Conclusions and recommendations
Developers of commercial solar PV in England may install systems with a capacity of up to 1MW without obtaining planning permission. However, the legislation states that there are still a number of factors that must be considered and rules that must be followed before installing the panels. These relate to the location of the property, the physical appearance of the panels on the property and the effect of solar glare on surrounding receptors.
There has already been an example where roof top PV panels on a domestic property have been removed due to glare towards the bedroom of an adjacent property (presented here).
The legislation can be interpreted such that a glint and glare assessment is required for all solar PV projects with a generative electrical capacity up to 1MW looking to obtain PD rights. Its purpose is to ensure no adverse effects are experienced which may subsequently lead to time and money being wasted.
Pager Power has the knowledge and experience to complete geometric glint and glare assessments with well over 100 comprehensive reports completed to date. If you require a glint and glare assessment for a small-scale commercial or domestic PV development to obtain PD rights, please get in touch.
Call +44 (0) 1787 319001 or email email@example.com.
Image accreditation: “rooftop solar panels” by h080 / CC BY-SA 2.0 / Image resized from original.
 The Town and Country Planning, (General Permitted Development) (England) Order 2015. (Last accessed 03/08/15).
 Article 2 (3) land pertains to an area designated as a ‘conservation area under section 69 of the Planning (Listed Buildings and Conservation Areas) Act 1990 (designation of conservation areas), an area of outstanding natural beauty, an area specified by the Secretary of State for the purposes of section 41(3) of the Wildlife and Countryside Act 1981 (enhancement and protection of the natural beauty and amenity of the countryside)(a), the Broads, a National Park and/or a World Heritage Site’.
 The Town and Country Planning, (General Permitted Development) (England) Order 2015, page 104 (Last accessed 03/08/15).