Domestic solar panels and the Class A Part 14 limits
Roof-mounted solar on a house is usually permitted development, including in conservation areas. The traps are flat roofs, walls fronting a highway and listed buildings.
Solar panels on the roof of a house are usually permitted development, including in a conservation area, provided they sit no more than 0.2 metres proud of the roof slope and no higher than the ridge. The exceptions that catch people out are listed buildings, scheduled monuments, walls facing a highway in a conservation area, and tilted frames on flat roofs. Class A of Part 14 of Schedule 2 to the General Permitted Development Order 2015 sets all of it out.
Read the limits before you buy the system, because the installer's quote will not mention them.
What Class A allows
Class A permits the installation, alteration or replacement of solar photovoltaic or solar thermal equipment on a dwellinghouse or a block of flats, and on a building within the curtilage such as a garage or outbuilding. The two dimensional limits are the ones that matter on a pitched roof:
- the equipment must not protrude more than 0.2 metres beyond the plane of the wall or the roof slope, measured perpendicular to that surface
- the highest part of the equipment must not be higher than the highest part of the roof, excluding any chimney
A standard in-plane roof mounting on a pitched roof clears both without difficulty. The order has been amended several times, so check the current text on legislation.gov.uk before relying on a figure quoted in a sales brochure.
This is general guidance, not legal advice, and a lawful development certificate is the only formal way to confirm that works are lawful. Check the position with your local planning authority or a qualified professional before relying on it.
The 0.2 metre rule and flat roofs
Here is where most domestic schemes fail. The protrusion is measured perpendicular to the roof surface, so on a flat roof the 0.2 metres is measured vertically.
Tilted frames on a flat roof are typically 300 to 500 mm high at the back of the panel, which puts them outside Class A immediately. Flat-laid panels on a flat roof stay within the limit and lose output. Neither answer is obviously right, and the honest position is that a flat-roofed house usually needs a planning application if you want the array tilted to a sensible angle.
| Situation | Position under Class A |
|---|---|
| In-plane panels on a pitched roof | Permitted, subject to the 0.2 m and ridge height limits |
| Tilted frame on a flat roof | Usually outside Class A, so permission needed |
| Panels on a garage or outbuilding in the curtilage | Permitted on the same terms |
| Panels on a wall fronting a highway in a conservation area | Not permitted, so permission needed |
| Any installation on a listed building | Not permitted, so permission needed |
Conservation areas
The common belief that solar panels are banned in conservation areas is wrong. Class A restricts one thing: in a conservation area or a World Heritage Site, the equipment must not be installed on a wall which fronts a highway. Roofs are not caught by that restriction, including front roof slopes.
Two caveats, both real. A council can make an Article 4 direction removing Class A rights across all or part of a conservation area, and some have. And the condition attached to Class A requires the equipment 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, which is a judgement a council could test later.
Check the council's online map for Article 4 directions before you commit. It takes a minute.
Listed buildings
Class A does not apply to installation on a listed building or on a building within its curtilage, so planning permission is required. Listed building consent is a separate application under the Planning (Listed Buildings and Conservation Areas) Act 1990 and will almost always be needed too, because fixings pass through historic fabric.
Applications do succeed. What makes the difference is siting out of principal views, usually on a rear slope or an outbuilding, using panels with a matt dark finish and black frames, running cables internally, and keeping the array to a simple rectangle aligned with the roof geometry. A short Heritage Statement identifying the significance of the building and explaining why the chosen slope causes the least harm is worth the effort.
What rarely succeeds is a front-slope array on a prominent listed frontage, however good the carbon case.
Ground-mounted arrays
An array on the ground falls under Class B of Part 14 rather than Class A, and the limits are tighter. Broadly, one standalone installation per curtilage, no more than 4 metres high, at least 5 metres from the curtilage boundary, with a panel surface area of no more than 9 m² and no dimension of the array greater than 3 metres. In a conservation area or World Heritage Site it must not be nearer to a highway bounding the curtilage than the nearest part of the house.
Nine square metres is around four or five panels, so Class B suits a top-up rather than a whole-house system. Larger ground arrays need an application. Different rules again apply to commercial canopies and farm-scale installations, which we cover in solar canopies over car parks and, for other rural generation, in farm wind turbines and permitted development limits.
Batteries, inverters and the rest of the kit
A battery installed inside the house, a garage or an existing outbuilding is not development at all, because it affects only the interior. An inverter on an internal wall is the same.
An external battery cabinet in the garden is a building, and whether it is permitted depends on Part 1 Class E, which covers buildings incidental to the enjoyment of the dwellinghouse, with its own limits on height, position and the proportion of the garden covered. Keep it behind the front elevation, keep it low, and check the Class E limits rather than assuming the battery rides along with the panels.
Two non-planning steps belong on the same checklist. The distribution network operator has to be notified of the connection, and a certified installation matters if you want an export tariff. Neither is a planning matter, and both get forgotten. If you are also considering a heat pump, the borehole and permitting questions are covered in ground source heat pumps and borehole permitting.
Proving it was lawful
Permitted development rights expire in the sense that they can be withdrawn, and buyers' solicitors ask awkward questions five years later. If your installation is near any of the limits, apply for a lawful development certificate for proposed use or development under section 192 of the Town and Country Planning Act 1990 before you install, or for existing works under section 191 afterwards.
The fee is lower than a full application and the certificate is a formal decision rather than an opinion. On a conveyancing timetable that is worth having.
An illustrative case: a 1930s semi in a conservation area with a south-facing front roof slope and a north-facing rear. The owner assumed the front was impossible and quoted for the rear, halving the output. The front slope was in fact permitted development, because the restriction applies to walls fronting a highway rather than roof slopes, and there was no Article 4 direction. A twenty minute check changed the economics of the whole installation.
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Frequently asked questions
Do I need planning permission for solar panels in a conservation area?
Usually not for a roof installation. Class A of Part 14 restricts installation on a wall which fronts a highway in a conservation area or World Heritage Site, and roof slopes are not caught by that restriction. Check whether the council has made an Article 4 direction removing the right, because some have in sensitive areas.
Can I tilt panels on a flat roof under permitted development?
Generally no. The 0.2 metre protrusion limit is measured perpendicular to the roof surface, which on a flat roof means vertically. Tilted frames are usually 300 to 500 millimetres high, so they fall outside Class A. Either lay the panels flat and accept lower output, or apply for planning permission for a tilted array.
What are the limits for a ground-mounted array?
Class B of Part 14 allows one standalone installation per curtilage, up to 4 metres high, at least 5 metres from the curtilage boundary, with a panel surface area of no more than 9 square metres and no array dimension over 3 metres. In conservation areas it must not sit nearer a bounding highway than the house does.
Do I need consent for solar on a listed building?
Yes, and two consents. Class A does not apply to a listed building or a building in its curtilage, so planning permission is required, and listed building consent is needed separately because fixings pass through historic fabric. Rear slopes, outbuildings, matt black panels and internal cable runs make approval far more likely.
Does a home battery need planning permission?
Not if it is inside the house, a garage or an existing outbuilding, because that affects only the interior. An external cabinet in the garden is a building and has to fit within Part 1 Class E for buildings incidental to the enjoyment of a dwellinghouse, with its own limits on height, siting and garden coverage.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.