Solar panels on houses: Part 14 Classes A and B

Most domestic solar panels go up without a planning application because solar panel permitted development is granted by Part 14 of the Town and Country Planning (General Permitted Development) (England) Order 2015. Class A covers equipment fixed to a house or a building in its curtilage. Class B covers a stand-alone array in the garden. Both come with limits that are easy to breach by accident, and both carry two conditions that stay with the installation for its whole life.

The rules are dimensional rather than discretionary. Get the projection, the ridge height and the boundary distance right and you do not need permission. Get one of them wrong and the whole installation is unlawful, which matters most when you sell.

What Class A allows on a roof

Class A permits the installation, alteration or replacement of microgeneration solar photovoltaic or solar thermal equipment on a dwellinghouse or a block of flats, and on a building within the curtilage of either. That last part covers a garage or a garden office roof.

The equipment has to be for microgeneration. A domestic roof array is comfortably within that. An installation designed to export at commercial scale from a house roof is not, and the fact that you have a grid connection agreement does not change the planning position.

Where the building is a block of flats rather than a house, Class A still applies, but ownership and the lease usually decide the question long before planning does. The roof of a converted building is often retained by the freeholder.

The 200 millimetre projection and the ridge line

Two dimensional limits do most of the work in Class A.

The equipment must not protrude more than 200 millimetres beyond the plane of the wall or the roof slope, measured perpendicular to that surface. On a pitched roof that is generous for in-plane or on-plane panels and tight for anything mounted on a raised frame.

The equipment must not sit higher than the highest part of the roof, excluding the chimney. Flat roofs are where installers get caught, because a tilted frame on a flat roof can breach both limits at once. Measure from the existing roof surface, not from the parapet.

Treat the table as the starting point and read the current text of Part 14 before you order the frame. The GPDO is amended often, and the version on legislation.gov.uk is the one that counts.

Stand-alone arrays in the garden under Class B

Class B covers a ground-mounted array in the curtilage of a house or block of flats. The array must not exceed four metres in height, must not be within five metres of the boundary of the curtilage, and the surface area of the equipment must not exceed nine square metres with no dimension over three metres including any housing or supporting framework.

Only one stand-alone installation is permitted within the curtilage. But a second array needs planning permission even where the first one is small and barely visible.

Nine square metres is roughly four or five panels. For most households that is a supplement to a roof array rather than an alternative to it, which is why ground-mounted domestic solar is far less common than the rules would suggest. A larger garden array is a full application, and on an open plot it will be assessed on visual impact and glint.

Conservation areas, listed buildings and Article 4

In a conservation area or a World Heritage Site, Class A does not permit wall-mounted solar on a wall that fronts a highway. Roof-mounted equipment on the rear or side slope is normally still permitted, though the siting condition below still applies.

Under Class B, in a conservation area or World Heritage Site the array must not be nearer to any highway bounding the curtilage than the part of the house nearest that highway. Neither class permits installation on a scheduled monument or within the curtilage of one.

Listed buildings are the bigger trap. Listed building consent under the Planning (Listed Buildings and Conservation Areas) Act 1990 is required for works affecting the special architectural or historic interest of the building, and that duty sits entirely outside the GPDO. Panels on a listed roof, and often on an outbuilding within its curtilage, need consent whatever Part 14 says. Assume consent is required, talk to the conservation officer early, and support the application with a Heritage Statement that addresses reversibility, fixings and views from the street.

An Article 4 direction can withdraw Part 14 rights for a defined area. They are less common for solar than for householder extensions, but they exist. Check the council's Article 4 register before you rely on permitted development.

The two conditions attached to every installation

Class A and Class B both carry the same pair of conditions, and they are easy to overlook because they are not dimensional.

First, the equipment must, so far as practicable, be sited to minimise its effect on the external appearance of the building and the amenity of the area. That is a genuine obligation, not a statement of intent. Putting an array on a front slope when the rear slope faces south-west at a similar yield invites an enforcement enquiry.

Second, the equipment must be removed as soon as reasonably practicable when it is no longer needed for microgeneration. Dead panels left on a roof for years are technically a breach.

Neither condition needs a council sign-off. Both can be the basis of an enforcement notice if a neighbour complains and the council agrees the siting was avoidable.

Battery storage and where it sits

Part 14 covers the generating equipment. It does not cover a battery.

A battery installed inside the house, in a garage or in an existing outbuilding is usually not development at all, because there is no building operation and no material change of use. A free-standing battery cabinet in the garden is a building operation, and its planning position comes from Part 1 Class E of the GPDO as an outbuilding incidental to the enjoyment of the dwellinghouse. Class E carries its own limits on height, position relative to the highway and total curtilage coverage.

That means the same installation can be lawful under two different classes with two different rulebooks. Where the battery cabinet sits forward of the principal elevation, or the property is in a conservation area, the outbuilding rules may bite even though the panels are fine.

Proving it was lawful when you sell

Permitted development leaves no paper trail. A conveyancing solicitor asking for evidence four years later will not accept an installer's word for it.

The clean answer is a lawful development certificate for existing use or development under section 191 of the Town and Country Planning Act 1990, or a certificate for proposed development under section 192 before you start. The proposed version costs less and moves faster, because you are describing a design rather than proving a history. A short Planning Statement setting out the projection, ridge height and boundary distances against the Part 14 wording is usually all the certificate application needs.

Keep the roof photographs, the panel specification and the installer's mounting detail. Those three documents answer nearly every question a purchaser's solicitor raises.

If the scheme also involves an outbuilding, a heat pump or an extension, check each element against its own class rather than assuming a single permitted development answer covers the lot. You can browse all 66 PlanScope report types to see which supporting documents a certificate or full application would need.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it, and remember that a lawful development certificate is the only formal way to confirm that works are lawful. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.