Permitted Development Rights: Non-Domestic Solar Panels and Domestic Air Source Heat Pumps

Some Questions Answered - Managing Impacts

Electrical or heat output of sir source heat pumps or solar panels

Question - Why is an output limit not being applied to air source heat pumps or solar panels?

In planning terms our primary concern for the technology is that it does not significantly harm the appearance or other good characteristic (amenity) of an area. An appropriately located system with a large energy output may have no harmful impacts and a poorly located system with a small energy output may have harmful impacts. However, it is generally impossible to tell for either technology what the output of the system is likely to be by looking at it. Therefore the output of the system is not always the best threshold by which to limit a development of air source heat pumps or solar panels under permitted development rights.

Non-Domestic solar panels

Question - Why limit wall and pitched roof solar panels to 200mm protrusion?

Walls and pitched roofs are likely to be the most visible surfaces of a building (when viewed from the adjacent street level). The proposed limit keeps the technology closely aligned to the existing building in visual terms. This is thought to be important as non-domestic buildings can be very large.

Question - What about glint, glare, dazzle and reflections?

We are aware that solar photovoltaic panels can reflect sunlight, sometimes known as glint, glare or dazzle when seen by people. We don't believe such reflections are caused by tubular solar thermal installations. Reflections from solar panels are not significantly different to those caused by other structures or installations containing glass panels or even from water. People will experience the reflections on sunny days and only when the angle of the sun, the solar panel and the position of the person coincide so that the person sees the reflected sunlight. As the position of the sun changes in the sky or the person moves position the reflection will no longer be experienced as glare or dazzle but may still be seen.

Question - Are there significant issues with existing solar panels?

Currently permitted development rights for solar panels on both domestic and non-domestic properties do not seek to reduce reflections. We are not aware that reflections from solar panels are causing a general problem. We do not intend that the permitted development rights should deal with reflection of light.

Question - What about aviation safety?

When we last consulted on permitted development rights for solar panels the Civil Aviation Authority raised potential concerns about the risk of dazzle to pilots. The Civil Aviation Authority interim guidance on solar panels (which pre-dates our previous consultation) highlights a concern around confusion of aeronautical lights (which are those used to inform aircraft pilots) and other lights (which could be caused by reflections).

The Civil Aviation Authority encourages developers and planning authorities to comply with the Air Navigation Order ( ANO) 2009. That addresses lights and is clear that if a the glare of a light is liable to endanger aircraft taking off or landing or could be mistaken for an aeronautical ground light and is liable to endanger an aircraft, the Civil Aviation Authority can direct the owner of the light (or the person otherwise in charge of it) to put out or screen it and prevent the light occurring again ^[2] .

In our previous consultation, BAA commented that glare should be managed within the aerodrome safeguarding area where as Infratil found that a 3km exclusion zone around the aerodrome was an appropriate starting point. That approach was also supported by the Ministry of Defence. However, since then domestic permitted development rights have allowed for solar panels across walls and roofs within 3km of aerodromes without planning applications being required. We are not aware that this has caused significant adverse impacts for airport operators.

Question - What about driver distraction?

Sunlight reflections may also have an impact on the road network.

Question - Are you addressing this in the proposals?

In both the aviation and road network instances we have not identified a standard level of reflectivity that would fully address the matter. Even if a level of reflectivity could be identified, enforcement through the planning system could be difficult as in a complaint situation it will not be possible to tell by looking at a solar panel whether it meets the reflectivity standard.

Question - How significant is the issue of glare and reflection?

Given that the sunlight reflections from solar panels will change over the course of a day and across the year, the impacts are temporary. This reduces their impact in general, whilst noting that an experience of glare can happen.

We have not been alerted to problems caused by sunlight reflections from solar panels installed on homes using permitted development rights within the safeguarded area of airports. Nor have we been alerted to problems for the road network caused by sunlight reflections from solar panels installed on homes under permitted development rights.

Question - Do the proposals address sunlight reflection?

We do not intend to restrict by location or reflectivity the installation of non-domestic solar panels through permitted development rights. Installers working in the vicinity of an aerodrome should be aware of the Air Navigation Order and discuss their proposal with the airport operator in advance to avoid post-installation action by the airport operator.

Question - What about radar interference from solar panels reflecting the radar electromagnetic waves?

The concern here is that the radar system for aircraft and air traffic control becomes less effective. Responses to the previous consultation indicate that BAA and Infratil considered radar interference to be an issue with BAA seeking consultation and Infratil considering an exclusion on permitted development rights of 3km area around the airport to be appropriate as a starting point. In contrast the Civil Aviation Authority did not raise this as a problem, nor did the UK's en-route Air Traffic Control provider ( NATS En Route plc or NERL). The Ministry of Defence provided explanatory information around radar operation focusing their comments on the effects of wind turbines.

As with sunlight reflection we have not been alerted to radar interference being a significant problem following the introduction of permitted development rights for solar panels on homes, which are not restricted close to airports or other sites where radar is operated.

Question - Will the additional height of a building after solar panels have been installed be a problem?

We propose that the solar panel should be set back from the edge of the roof by a distance at least equal to the height of the solar panel (when installed). This set back means that that the additional height of the building is not as apparent form the area immediately adjacent to the building, thereby lessening the impact. In previous consultations, the potential for aircraft striking a solar panel mounted on a flat roof has been raised. However we are not aware that this has been a problem following the introduction of permitted development rights for solar panels on homes. The set-back distance of the panel from the edge of the roof also reduces the risk as aircraft will already be avoiding getting too close to existing buildings.

Question - Won't the height of the solar panels on a flat roof significantly alter the appearance of the building?

An alteration of the appearance of the building could occur but this could be no different in terms of overall impact than changing the style of the windows or painting the building a different colour. The change could be felt to be significant by some people, others will disagree. The set-back proposal means that views of the solar panels will be restricted from ground level and close to the building. Further away and from elevated locations, the solar panels will be more visible. However, distance from a building helps ensure that the building can be seen more as a whole and in relation to its surroundings, allowing the solar panels to be seen as part of the building rather than as a distinctive feature in their own right.

For new buildings where, in the view of the planning authority, the design and appearance could be adversely impacted by the installation of solar panels, the planning authority could apply a condition to the planning permission which removes the permitted development rights. We expect that this is unlikely to be necessary in most instances.

The Scottish Government more generally is promoting renewable energy in a variety of forms through legislation and policy. The permitted development rights help to make the technology a normal part of place and our environment, something which could help increase their acceptability to more people over time.

Domestic Air Source Heat Pumps

Question - Are air source heat pumps noisy?

Everyone perceives sounds differently. Some people find some levels of sound more acceptable than others. Some people find some types of sound more acceptable than others. In England, where permitted development rights based on the microgeneration scheme have been introduced, complaints about the sound of air source heat pumps have not been significant ^[3] .

Making use of the microgeneration certification scheme in the permitted development rights should provide a threshold for sound that neighbours of air source heat pumps will find acceptable.

Many air source heat pump installations financially benefit from the Renewable Heat Incentive scheme. That scheme is subject to the microgeneration certification scheme and so it is appropriate that the permitted development rights make use of it as well.

With the installation of an air source heat pump the sounds experienced in an area will change. The planning system, either by permitted development rights or planning permission, is not designed to prevent change, but to ensure that changes proposed are generally acceptable. Properties using air source heat pumps generally won't also use gas boilers for heating and hot water purposes. Gas boilers are not silent in operation and have an impact on the sounds experienced in an area. The sounds made by air source heat pumps and gas boilers are different and we do not suggest one is more acceptable than another, we only make the point that neither are silent in operation. Where gas boiler flues are not generally controlled through the planning system, air source heat pumps are and will need to conform to the standards within it.

Question - If I am bothered by an air source heat pump, can I complain?

Yes. Initially you should contact the planning enforcement team to understand if the air source heat pump has either met the terms of its planning permission or permitted development rights. If it has, you can contact the council's environmental health team who can discuss what action might be appropriate.

Question - If one air source heat pump is found to cause a statutory noise nuisance, aren't all of them nuisances?

No. The particular circumstances of an installation may mean that the sounds generated by an air source heat pump are causing a noise nuisance for a neighbour. This is site specific and may even be to do with maintenance of a heat pump. It does not mean that all other air source heat pump installations will cause a nuisance.

Question - What about the visual impacts of air source heat pumps?

Air source heat pumps for domestic situations tend not to be large pieces of equipment. Generally, the visible parts of the unit will be a metal box casing, with ventilation slots plus an inlet for electrical cable and, pipework connecting the unit to the house. Visually, air source heat pumps are not any different to a multitude of other small additions a home owner may make to their property. With the 1 meter bubble concept for additions that don't increase the floor space of a dwelling, the Scottish Government has broadly determined that small additions are acceptable.

We do not anticipate that visual impacts will be significant. However our proposals do seek to protect principal and side elevations from installations above ground floor level.