UK Commercial Solar Planning Permission and Permitted Development Class J Guide

Key Takeaways

• Commercial solar PV on non-domestic buildings is permitted development under Schedule 2, Part 14, Class J of the the 2015 General Permitted Development Order.
• Statutory amendments under Statutory Instrument No. 1279 of 2023 formally repealed the former 1 megawatt (1MW) capacity cap on non-domestic rooftop arrays.
• On commercial flat roofs, equipment must not rise higher than 1 metre above the roof and must be set back at least 1 metre from the roof edge.
• On pitched roofs, panels must not protrude more than 0.2 metres beyond the roof slope plane.
• Commercial wall-mounted systems must project no more than 0.2 metres and remain at least 1 metre from junctions with other walls or roofs.
• Class J rights do not apply to listed buildings or buildings within the curtilage of a listed building.

The Scope of Class J Permitted Development

Commercial solar installations in England operate under Schedule 2, Part 14, Class J of the Town and Country Planning (General Permitted Development) (England) Order 2015.

Class J permits the installation, alteration or replacement of microgeneration solar thermal equipment, microgeneration solar PV equipment, or other solar PV equipment on the roof or walls of a building, explicitly applying to non-domestic premises other than a dwellinghouse or a block of flats. This framework covers industrial manufacturing plants, logistics warehouses, agricultural barns, commercial offices, and retail parks.

Repeal of the 1 Megawatt (1MW) Capacity Cap

Historically, commercial rooftop solar installations exceeding 1 megawatt required a full planning application. This threshold created unnecessary delays for large commercial and industrial rooftops capable of supporting multi-megawatt generation.

Under the Town and Country Planning (General Permitted Development etc.) (England) (Amendment) (No. 2) Order 2023 (Statutory Instrument No. 1279 of 2023):

• Paragraph J.3 of Class J, which restricted capacity to 1 megawatt, was formally omitted.
• Commercial rooftop arrays can now exceed 1MW under permitted development rights, subject to relevant prior approval considerations.
• The statutory amendment also omitted paragraph J.1(d), removing previous highway frontage restrictions on article 2(3) land for non-domestic roof slopes.

Technical Setback and Dimensional Constraints

To qualify for permitted development under Class J, commercial solar arrays must respect strict geometric setbacks:

Pitched Roof Installations

• Equipment installed on a pitched roof must not protrude more than 0.2 metres beyond the plane of the roof slope when measured perpendicular from the external surface.

Flat Roof Installations

• Maximum Height: Where equipment is installed on a flat roof, the highest part of the solar PV equipment must not be higher than 1 metre above the highest part of the roof (excluding any chimney).
• Perimeter Safety Setback: Equipment must not be installed within 1 metre of the external edge of that roof. This 1-metre perimeter buffer ensures visual containment from ground level and safe maintenance access.

Wall-Mounted Installations

Where solar PV is mounted onto commercial building elevations:

• Panels must not protrude more than 0.2 metres from the wall surface.
• Panels must not be installed within 1 metre of a junction of that wall with another wall or with the roof of the building.

Heritage and Conservation Exclusions

Commercial permitted development rights under Class J do not apply across protected heritage assets:

• Development is strictly not permitted if equipment would be installed on a listed building or on a building within the curtilage of a listed building.
• Installations on sites designated as scheduled monuments are excluded from Class J rights.
• For stand-alone non-domestic solar under Class K, installations on article 2(3) land closer to a bounding highway than the nearest part of the building are restricted to 2 metres in height.

Statutory Conditions and Decommissioning Obligations

All commercial Class J developments are governed by mandatory statutory conditions:

1. Appearance Minimisation: Solar PV equipment must, so far as practicable, be sited so as to minimise its effect on the external appearance of the building.
2. Removal Obligation: Solar equipment must be removed as soon as reasonably practicable when no longer needed for electricity generation.