Planning Permission for Commercial Rooftop Solar PV (England)

What Class J covers

Class J of Part 14, Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015 is the rule that decides whether a roof array on a business building needs a planning application. It permits three kinds of work on buildings that are not dwellinghouses or blocks of flats: microgeneration solar thermal equipment, microgeneration solar PV equipment on a building, and "other solar PV equipment on the roof of a building".

The split between the second and third limb is size. "Microgeneration" takes its meaning from section 82 of the Energy Act 2004, which caps it at 50 kilowatts of electrical capacity. So a rooftop system up to 50 kW sits in the straightforward limb, and a larger rooftop array is the "other solar PV" limb, which carries an extra step (see below). Class J has no kW ceiling of its own: the limits that apply to a 400 kWp warehouse roof are the same physical ones that apply to a 30 kWp office roof.

The three limits that shape the design

Paragraph J.1 lists what is not permitted. For a roof array, three limits do the work:

• Pitched roof: the equipment must not protrude more than 0.2 metres beyond the plane of the roof slope. That means flush-mounted or close-to-roof on-roof systems.
• Flat roof: the highest part of the PV equipment must not be more than 1 metre above the highest part of the roof.
• Roof edge: the equipment must not be installed within 1 metre of the external edge of the roof.

The flat-roof limit is a geometry check, and it is one reason low-tilt layouts dominate commercial flat roofs. For a module about 2.3 m long (typical of current commercial modules), the height of the top edge above its support is roughly 2.3 m multiplied by the sine of the tilt: about 0.4 m at 10°, about 0.6 m at 15° and about 1.15 m at 30°. A 30° south-facing rack therefore breaks the 1 m limit before the frame and ballast tray are even added, while a 10° to 15° east-west layout stays comfortably inside it. The same arithmetic also explains the yield trade-off set out in kWh per kWp by UK region and roof layout. These are worked examples with an assumed module length, not a substitute for the structural and mechanical designer's own drawing; measure from the real rack against the highest part of the roof.

What is excluded

Class J does not apply on a scheduled monument site, and it does not apply to a listed building or within the curtilage of one. Those need planning permission, and a listed building needs Listed Building Consent as well. For equipment fixed to a wall rather than a roof (Class J(a) and (b) only), paragraph J.2 adds that it must not protrude more than 0.2 metres, must not sit within 1 metre of the junction with another wall or the roof, and, on article 2(3) land, must not be on a wall that fronts a highway.

The version of Class J on legislation.gov.uk (read 20 October 2026) has had several amendments, most recently S.I. 2023/1279 (in force 21 December 2023) and S.I. 2026/313 (in force 9 April 2026). Older guides, including some installer pages, describe the earlier text, so check the revised wording, not a summary of it. Councils can also withdraw permitted development rights locally through an Article 4 direction, so a quick call to the planning authority is worth making on any site in a designated area.

Arrays over 50 kW: the prior-approval step

Where the array falls in the "other solar PV equipment on the roof" limb, paragraph J.4(2) makes permitted development conditional on applying to the local planning authority before starting for a determination whether its prior approval is needed. The matters it can consider are the design or external appearance of the development, "in particular the impact of glare". The authority publicises the proposal by site notice for at least 21 days or by notifying adjoining owners or occupiers, and the work must not begin until the authority gives notice of its decision or 56 days pass without one.

In practice the 56-day period makes the prior-approval route an item of up to eight weeks on the programme for a large roof, and the glare assessment is the document the authority will want: where the array faces neighbouring windows, an airfield or a road, show the modules' orientation and tilt against those receptors.

Conditions that always apply

Two conditions in J.4(1) apply to every Class J installation. 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, and it must be removed as soon as reasonably practicable when no longer needed. The removal condition is worth remembering for lease and end-of-life clauses.

England only

Everything above is the English order. Scotland, Wales and Northern Ireland each have their own planning rules for solar, with different thresholds, so do not carry the 0.2 m, 1 m and 1 m figures across the border without checking the devolved text.

A planning checklist for the specifier

• Is the building listed, in a listed building's curtilage, or on a scheduled monument site? If so, Class J is out.
• Is the array 50 kW or less, or larger? Larger means a prior-approval determination before work starts.
• Is the highest point of the array within 1 m of the highest part of a flat roof (or 0.2 m of a pitched slope), and is every module at least 1 m from the roof edge?
• Are any panels on a wall? Then check J.2, and article 2(3) land.
• Has anyone confirmed there is no Article 4 direction on the site?

Planning is one of several design decisions in a full specification; the rest of that process is set out in our guide to commercial PV systems, and the mounting choice that drives it in rooftop vs ground-mounted vs solar carport. If you want a second pair of eyes on a specific roof, you can send the site details and we reply by email.

Sources

• Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 14, Class J, revised text on legislation.gov.uk, read 20 October 2026.
• Energy Act 2004, section 82 (microgeneration, 50 kW electrical), read 20 October 2026.

This guide is general information, not legal advice. Confirm the position for a specific building with the local planning authority.