Do You Need Planning Permission for Commercial Rooftop Solar in 2026?

For most commercial rooftops in England, the short answer is no — you do not need a full planning application. Rooftop solar is permitted development, and the 1 MW size cap that used to push larger arrays into the planning system was removed on 21 December 2023. But “permitted development” is not the same as “no process”, and the part of the project most likely to stall is not planning at all. It is the grid connection. This is the 2026 reality for owners, landlords and asset managers.

A note on scope before we go further: the planning rules below apply to England only. Scotland, Wales and Northern Ireland operate their own permitted development regimes, and the thresholds differ.

The 1 MW cap is gone

Until late 2023, rooftop solar above 1 MW of generating capacity fell outside permitted development and needed a full planning application — a real constraint on large warehouse and distribution roofs, where 1 MW is roughly 5,000–7,000 m² of panel.

The Town and Country Planning (General Permitted Development etc.) (England) (Amendment) Order 2023 (SI 2023/1279) removed that cap on 21 December 2023. There is now no upper size limit on rooftop solar under permitted development in England. A 2 MW array on a single logistics shed is, in principle, permitted development in the same way a 50 kW array on a small office is.

That is a genuine unlock for industrial and logistics property, where roof area is the limiting factor rather than load.

So what is “permitted development”, exactly?

Permitted development rights let you carry out certain works without a full planning application — but they come with conditions, and several of them have a procedural step built in.

Rooftop solar on a commercial building falls under Class J of Part 14 of the GPDO. Class J allows the installation of solar PV (and solar thermal) equipment on the roof of a non-domestic building, subject to limits and a prior-approval requirement.

Prior approval is not the same as planning permission, but it is not nothing either. Before installation, you notify the local planning authority, which then has 56 days to decide whether it wishes to approve specific matters — principally the design and external appearance of the equipment and, for larger or more sensitive sites, glint and glare. If the authority does not respond within 56 days, you can proceed. Glint and glare matters most near airfields, busy roads and overlooked residential windows, and a short glint-glare assessment is a sensible thing to have ready.

Treat the 56 days as a real line item in your programme, not a formality you can skip.

The Class J limits you have to stay inside

Permitted development applies only if you stay within the conditions. The ones owners trip over most:

Flat-roof commercial buildings are common and worth a word: tilted-frame arrays on a flat roof can exceed the 0.2 m projection limit depending on how they are mounted, which can take the installation outside Class J and into a full application. This is a design decision your installer should be flagging at survey, not something you discover at planning.

Car-park canopies are a different class

If your asset includes parking, solar canopies over the car park are covered separately under Class OA (the solar car-port class), not Class J. The principles are similar — permitted development with conditions and a prior-approval step — but the limits, height allowances and siting tests differ. If you are weighing roof versus canopy, treat them as two distinct planning questions rather than assuming the roof answer carries across.

When permitted development does not apply

Class J carves out a meaningful set of buildings and locations. You will need a full planning application — and possibly listed building or scheduled monument consent — where any of the following apply:

• Listed buildings. Solar on or within the curtilage of a listed building is outside permitted development and needs both planning permission and listed building consent.
• Scheduled monuments. Excluded outright.
• Conservation areas and World Heritage Sites. Permitted development rights are restricted; equipment on a principal or side elevation fronting a highway is typically excluded, and roof installations may be constrained.
• Article 4 directions. A local authority can issue an Article 4 direction that withdraws permitted development rights for a defined area or building type. If one is in force over your asset, the default “no application needed” answer flips. Check the local planning authority’s records before you assume Class J applies.

None of these makes solar impossible — plenty of listed and conservation-area buildings carry panels — but they change the route, the timeline and the cost, and they belong in your due diligence before you commit to a target install date.

The real bottleneck in 2026: the grid

Here is the part owners underestimate. Once you are clear of planning, the longest pole in the tent is almost always the connection to the distribution network.

Any solar installation above roughly 50 kW generally requires a G99 application to the local Distribution Network Operator (DNO) before it can connect and export. G99 is the engineering recommendation governing how generation connects to the grid; below ~50 kW the lighter-touch G98 process applies, but most commercial rooftops sit well above that line.

A G99 application is an assessment of whether the local network can accept your generation. The DNO will either accept the connection, accept it with conditions, or quote for reinforcement works if the network in your area is constrained. On a congested part of the network, reinforcement can be expensive and slow — and in some areas the practical answer is a connection offer with a long lead time. DNO response and connection timescales can run from a couple of months to well over a year depending on the area and the size of the array.

The lever that keeps many projects viable is export limitation under G100. If you cap exported power — using an export limitation scheme so the array only ever pushes a defined amount onto the grid — you can often secure a faster, cheaper connection while still self-consuming the bulk of what you generate on site. For a high-load building that consumes most of its solar anyway, an export-limited connection frequently makes more economic sense than waiting and paying for reinforcement to enable full export.

The single most useful thing an owner can do is start the G99 conversation early — ideally in parallel with, or even ahead of, the planning prior-approval step. The grid answer determines what size of system is actually deliverable, and it is the variable most likely to reshape the project. Designing the array first and discovering the connection constraint second is how programmes slip by quarters.

What this means for your programme

For a typical unlisted commercial building in England, outside a conservation area and with no Article 4 direction, the planning path is straightforward: Class J permitted development with a 56-day prior-approval window. The work that determines whether the project lands on time and at the size you modelled sits on the grid side — the G99 application, any reinforcement, and the export-limitation decision.

Sequenced properly, the two run together: prior-approval notification and G99 application submitted in parallel, glint-glare assessment ready if the site warrants it, and the system sized to the connection the DNO will actually give you rather than the roof area you happen to have. We cover the full sequence — and how it interacts with capital allowances and ownership structure — in our planning and grid guide for commercial solar.

If you want a read on your specific roof — whether Class J applies, where the conservation or Article 4 traps might be, and what the realistic G99 picture looks like for your postcode — request a quote and we will map the planning and grid route alongside the numbers.