The short answer
Rooftop solar on a business building in England often does not need a planning application. It can be permitted development under Class J of Part 14, Schedule 2 of the Town and Country Planning (General Permitted Development) (England) Order 2015 (the GPDO), provided it stays within the limits below. The main exceptions are roof arrays above 50 kW, which need a prior approval application first, and listed buildings and scheduled monuments, which fall outside Class J.
What Class J covers
Class J applies to solar on a building other than a dwellinghouse or a block of flats, such as a factory, warehouse, office or farm building. It has three parts:
- J(a): microgeneration solar thermal equipment on a building.
- J(b): microgeneration solar PV equipment on a building.
- J(c): other solar PV equipment, on the roof of a building only.
"Microgeneration" takes its meaning from section 82 of the Energy Act 2004: plant with a capacity of no more than 50 kilowatts of electricity or 45 kilowatts thermal. So PV up to 50 kW falls under J(b); larger arrays fall under J(c), on roofs only.
The limits on a business roof
| Where the panels go | Not permitted development if… |
|---|---|
| Pitched roof | the equipment protrudes more than 0.2 metres beyond the plane of the roof slope |
| Flat roof | its highest part is more than 1 metre above the highest part of the roof (excluding any chimney) |
| Any roof | it is within 1 metre of the external edge of the roof |
| Wall (J(a) and J(b) only) | it protrudes more than 0.2 metres, is within 1 metre of a junction with another wall or the roof, or is on a wall fronting a highway on protected (article 2(3)) land |
All Class J work must, so far as practicable, be sited to minimise its effect on the external appearance of the building and the amenity of the area. It must be removed as soon as reasonably practicable once no longer needed. Class J sets no capacity cap: S.I. 2023/1279 removed the 1 megawatt threshold from 21 December 2023.
Systems above 50 kW: the prior approval step
Before starting a J(c) installation, you must ask the local planning authority to decide whether its prior approval is needed for the design or external appearance of the development, in particular the impact of glare on occupiers of neighbouring land. This is not a full planning application. You send a written description, a plan showing the site and the proposed development, your contact address and any required fee.
The council gives notice with a site notice for at least 21 days, or by serving notice on adjoining owners or occupiers. It takes representations into account and can refuse an application that breaks the Class J limits or lacks enough information. Work can start once you are told prior approval is not required, once approval is given, or 56 days after the council received the application if it has not told you whether prior approval is given or refused.
The prior approval step is not in itself a reason to cut a design back to 50 kW. Size the system to the building's electricity use first.
What changed on 27 August 2026, and what did not
S.I. 2026/896 came into force on 27 August 2026. It rewrote the domestic solar limits in Classes A and B and added definitions of "plug-in solar" and "roof enclosure". Domestic installations that were permitted immediately before 27 August 2026, but that the change took out of permitted development, can still go ahead until the end of 26 August 2027. It did not amend Class J, Class K or Class OA, so the business limits on this page were not changed by it. For the householder side, see our guide to planning permission for home solar panels.
Conservation areas and other protected land
"Article 2(3) land" means conservation areas, areas of outstanding natural beauty, National Parks, the Broads, World Heritage Sites and areas specified under section 41(3) of the Wildlife and Countryside Act 1981. On that land, Class J adds one restriction: no J(a) or J(b) equipment on a wall fronting a highway. It sets no extra limit on roofs there, because S.I. 2023/1279 removed the old rule against equipment on a roof slope fronting a highway.
Listed buildings and scheduled monuments
Class J does not apply to a listed building, a building within a listed building's curtilage, or a site designated as a scheduled monument, so rooftop solar there needs a planning application. Listed building consent is also required under section 7 of the Planning (Listed Buildings and Conservation Areas) Act 1990 for works that alter a listed building in a way that would affect its character as a building of special architectural or historic interest. Works that alter or add to a scheduled monument need scheduled monument consent from the Secretary of State under section 2 of the Ancient Monuments and Archaeological Areas Act 1979.
Ground-mounted arrays and car-park canopies
Class K permits stand-alone microgeneration solar within the curtilage of a non-domestic building. You can have one stand-alone installation with no more than 9 square metres of panels, no array dimension (including any housing) over 3 metres and no part over 4 metres high. No part can be within 5 metres of the curtilage boundary, within a listed building's curtilage or on a scheduled monument. On article 2(3) land, an array nearer the highway than the building is limited to 2 metres high and needs a prior approval application about its appearance. A ground-mounted array bigger than this falls outside Class K and will normally need a planning application.
Class OA permits solar canopies over areas lawfully used as off-street parking, other than parking for a house or block of flats. No part can be more than 4 metres above ground level or within 10 metres of the curtilage of a house or block of flats. Canopies are not allowed within a listed building's curtilage or on or within the curtilage of a scheduled monument. Every canopy needs a prior approval application covering siting, design and external appearance, including glare, and must be completed within 3 years of that stage.
When you need a full planning application
- The building is listed, within a listed building's curtilage, or on a scheduled monument.
- The design breaks a Class J limit, such as the 1 metre edge gap.
- A ground-mounted array is larger than Class K allows.
- An Article 4 direction by the council or the Secretary of State has removed the rights.
- A condition on an existing planning permission for the site rules it out. Article 3(4) of the GPDO says the Order does not permit development contrary to such a condition.
For certainty, you can apply to the council under section 192 of the Town and Country Planning Act 1990 for a certificate confirming that the proposed work would be lawful.
For sizing, grid and funding questions, see our commercial solar Yorkshire page. Running a large shed roof? See our page on solar for warehouses and logistics buildings.
