Solar panels on a house under Part 14 of the GPDO

Solar panels on a house are permitted development in most cases, under Class A of Schedule 2 Part 14 to the Town and Country Planning (General Permitted Development) (England) Order 2015. The limits are narrow and specific: the equipment must not stick out more than 200 millimetres from the roof slope or wall, it must not sit higher than the highest part of the roof apart from the chimney, and on protected land it must not go on a wall that faces a highway. Miss one of those and you need planning permission.

Part 14 is the microgeneration part of the Order. It covers solar photovoltaic and solar thermal equipment on a dwellinghouse or a block of flats under Class A, and free standing arrays in the garden under Class B.

What Part 14 allows on a house

Class A permits the installation, alteration or replacement of solar equipment on a dwellinghouse or on a building within its curtilage, which includes a garage or an outbuilding. Both electricity generating panels and solar thermal collectors for hot water are covered by the same class.

The permission is subject to conditions rather than a simple size allowance. The equipment has to be sited, so far as practicable, to minimise its effect on the external appearance of the building and on the amenity of the area. That wording matters if a neighbour complains later, because a panel array bolted across a decorative gable when a rear slope was available is vulnerable to the argument that the condition was not met.

Class A does not apply where the building is a scheduled monument or sits within the curtilage of one.

The 200 millimetre projection limit

The projection limit is measured from the plane of the wall or the roof slope to the outermost point of the equipment, and it includes the mounting frame as well as the panel. Two hundred millimetres is enough for a standard on roof rail system on a pitched roof. It is not enough for a tilted frame on a flat roof, which is where most householder schemes fall out of Part 14.

A flat roof array on angled frames will almost always exceed the projection limit, so a flat roofed extension, dormer or garage usually needs a full application even though the panels are barely visible from the street. In roof panels set flush into the covering pass the test comfortably.

The second limit is height. The highest part of the equipment must not be above the highest part of the roof, excluding any chimney. On a hipped roof with a short ridge, a large array pushed up the slope can breach this without anyone noticing on the drawings.

Wall mounted panels and the principal elevation

Wall mounted panels are permitted on a normal house anywhere on the building, subject to the same 200 millimetre projection limit. The restriction bites on article 2(3) land.

Article 2(3) land means a conservation area, a World Heritage Site, a National Landscape (formerly an Area of Outstanding Natural Beauty), a National Park or the Broads. On that land, Class A does not permit solar equipment on a wall which forms the principal elevation of the dwellinghouse and fronts a highway. A side wall facing the street can still qualify, and a rear wall almost always does, so the design answer is often a change of elevation rather than an application.

Work out which elevation is the principal one before you rely on this. It is normally the elevation containing the main architectural treatment and the front door, and it does not change simply because a later extension moved the entrance.

Conservation areas, listed buildings and protected land

Roof mounted panels in a conservation area are not automatically excluded from Part 14. The wall restriction above is the specific protected land limitation for solar, and roof slopes remain permitted development unless an Article 4 direction has removed the right.

Article 4 directions are the trap. Many conservation areas carry a direction removing householder permitted development for alterations visible from the highway, and some name microgeneration equipment directly. Check the council's list of directions for your address rather than assuming the general position applies.

Listed buildings are a separate consent regime. Works that affect the special architectural or historic interest of a listed building need listed building consent under the Planning (Listed Buildings and Conservation Areas) Act 1990, whether or not planning permission is required, and fixing panels through a historic roof covering will affect that interest. Expect the council to ask for a short Heritage Statement setting out the significance of the building, the effect of the installation and why a less harmful position was rejected. A related note on solar panels and listed buildings goes through the consent position in more detail.

Stand alone arrays in the garden

Class B of Part 14 covers a free standing array within the curtilage of a dwellinghouse, and the limits are tighter than most people expect:

• only one stand alone installation within the curtilage
• no part higher than four metres
• at least five metres from the boundary of the curtilage
• the panel surface area no greater than nine square metres
• no single dimension, including any framework, greater than three metres

Nine square metres is a small array by modern standards, roughly four or five panels. A garden array sized to run a heat pump will usually exceed it and need permission.

On article 2(3) land, a stand alone array must not be visible from a highway that bounds the curtilage. Within the curtilage of a listed building, Class B does not apply at all.

Taking the equipment down

Both classes carry a removal condition. The equipment must be removed as soon as reasonably practicable when it is no longer needed for microgeneration. That is a live obligation rather than a formality, and it is the reason a failed or disconnected array left on a roof for years can attract an enforcement enquiry.

The reinstatement point is worth flagging to clients on older roofs. Removing an array after fifteen years leaves fixings through the covering, and making good is not covered by the permitted development right.

When a full application is needed

You need planning permission where the projection exceeds 200 millimetres, where the array would sit above the ridge, where a wall array faces a highway on protected land, where an Article 4 direction applies, where the stand alone limits are exceeded, or where the building is within the curtilage of a listed building for Class B purposes.

For a householder application the council will want existing and proposed elevations showing the panels at scale, a roof plan, a site location plan and, in a sensitive area, a short design justification. Similar considerations apply to other alterations that change the appearance of a front elevation, such as rendering or cladding a house, and the drawings need to show the existing condition as clearly as the proposal.

Where the works fall within permitted development but you want certainty, apply for a Lawful Development Certificate under section 192 of the Town and Country Planning Act 1990. That is the only formal way to confirm that an installation is lawful, and it is worth having when the house is sold.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. If the panels fall outside Part 14 and you need supporting documents, enter your postcode on PlanScope to see which reports the application is likely to need. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.