Permitted development for solar: the actual rules

Class A — solar on a building

The grant itself is broad:

The installation, alteration or replacement of microgeneration solar PV or solar thermal equipment on— (a) a dwellinghouse or a block of flats; or (b) a building situated within the curtilage of a dwellinghouse or a block of flats.

Note what that includes: alteration and replacement, not just first installation. Replacing an existing array is within the class on the same terms.

What is not permitted — A.1

Five limbs. Development is not permitted by Class A if:

(a) Protrusion. The equipment

would protrude more than 0.2 metres beyond the plane of the wall or [in the case of a pitched roof,] the roof slope when measured from the perpendicular with the external surface of the wall or [pitched] roof slope

The bracketed words were inserted in December 2023. Measured from the perpendicular — so it is the depth of the whole assembly away from the surface, not its thickness alone. Standard on-roof rails and modules on a pitched roof are comfortably inside 0.2 m. Frames that tilt panels up away from a shallow pitch may not be.

(b) Height on a pitched roof.

in the case of solar PV or solar thermal equipment on a pitched roof, it would result in the highest part of the solar PV or solar thermal equipment being higher than the highest part of the roof (excluding any chimney)

So: not above the ridge. Chimneys are expressly excluded from the comparison, which means a tall chimney does not buy you height.

(ba) Height on a flat roof. Inserted 21 December 2023:

in the case of solar PV or solar thermal equipment on a flat roof, it would result in the highest part of the solar PV or solar thermal equipment being more than 0.6 metres higher than the highest part of the roof (excluding any chimney)

This is the one to know. A flat roof gets a 0.6 metre allowance, which is what makes a tilted frame possible — and it is a real constraint on how steeply you can mount, because a 2-metre panel at 20° rises about 0.68 m before you add the frame.

(c) Walls fronting a highway on protected land.

in the case of land within a conservation area or which is a World Heritage Site, the solar PV or solar thermal equipment would be installed on a wall which fronts a highway

Walls. Not roofs. This is the most widely misdescribed provision in the whole part, and it has its own page: conservation areas.

(d) Scheduled monuments. Not permitted, without qualification.

(e) Curtilage buildings of a listed dwellinghouse.

the solar PV or solar thermal equipment would be installed on a building within the curtilage of the dwellinghouse or block of flats if the dwellinghouse or block of flats is a listed building

Read that carefully — it excludes the outbuilding, where the house is listed. It does not, by its terms, exclude the listed house itself from Class A. That surprises people, and it does not mean what they hope: see listed buildings.

Conditions — A.2

Permitted development under Class A is subject to these:

(a) solar PV or solar thermal equipment is, so far as practicable, sited so as to minimise its effect on the external appearance of the building; (b) solar PV or solar thermal equipment is, so far as practicable, sited so as to minimise its effect on the amenity of the area; … (c) solar PV or solar thermal equipment is removed as soon as reasonably practicable when no longer needed.

And, inserted in December 2023, a prior approval requirement:

(ba) in the case of solar PV or solar thermal equipment installed on a flat roof located on article 2(3) land, before beginning development the developer must apply to the local planning authority for a determination as to whether the prior approval of the local planning authority will be required with respect to the impact of the appearance of the solar PV or solar thermal equipment on that land

Class B — standalone and ground-mounted solar

The installation, alteration or replacement of stand-alone solar for microgeneration within the curtilage of a dwellinghouse or a block of flats.

“Stand-alone solar” is defined in the order as “solar PV or solar thermal equipment which is not installed on a building”.

What is not permitted — B.1

Two of those are much tighter than people expect.

Nine square metres of panel is roughly 4 to 5 modern panels — on the order of 2 kWp. A ground-mounted array of any real size is not permitted development and needs planning permission.

Five metres from the boundary rules out most small gardens entirely, before the area limit even applies.

Within the curtilage of a listed building, standalone solar is excluded outright — a stricter rule than Class A applies to the building itself.

Conditions — B.2

Minimise the effect on the amenity of the area so far as practicable, and remove when no longer needed. Plus, since December 2023, a prior approval requirement where a standalone array in a conservation area sits nearer to a bounding highway than the house does.

What “article 2(3) land” means

Several provisions turn on it. Schedule 1, Part 1 of the order defines it as:

• an area designated as a conservation area under section 69 of the Planning (Listed Buildings and Conservation Areas) Act 1990
• an area of outstanding natural beauty
• an area specified for the purposes of section 41(3) of the Wildlife and Countryside Act 1981
• the Broads
• a National Park
• a World Heritage Site

If your property is on any of those, the flat-roof prior approval condition applies to you.

Other definitions worth knowing

“Block of flats” means a building which consists wholly of flats. A shop with flats above is not a block of flats for these purposes, which changes which class applies.

“Microgeneration” takes its meaning from section 82(6) of the Energy Act 2004.

“Solar canopy” — a canopy structure installed with solar equipment, open on all sides or, where it adjoins a building, on three. There is a separate class, Class OA, for solar canopies over non-domestic off-street parking. It expressly does not apply to parking for a dwellinghouse or block of flats, so it is not a route for a domestic carport.

A practical checklist

Before assuming permitted development:

1. England? If not, this page does not apply.
2. Listed? Stop and read listed buildings.
3. Article 2(3) land? Read conservation areas, and note the flat-roof prior approval requirement.
4. Scheduled monument? Not permitted.
5. Pitched roof: under 0.2 m protrusion, not above the ridge.
6. Flat roof: not more than 0.6 m above the highest part.
7. Article 4 direction in force? Rights may have been withdrawn. Ask the authority.
8. Close to any limit? Apply for a lawful development certificate.