Planning permission for commercial solar — when you need it, and when you don't

Good news first: for the large majority of UK businesses, putting solar on your roof needs no planning application at all. It falls under "permitted development" — pre-approved by national rules, no council application required. And it got much easier recently: in November 2023 the government removed the old 1MW cap that had forced larger rooftop arrays to seek permission. Today a sizeable commercial rooftop system on an ordinary building is, in most cases, permitted development.

But "most cases" isn't "all cases," and there are separate consents that catch people out even when planning is fine. Here's the real picture.

When rooftop solar is permitted development (no application needed)

For a standard commercial building, roof-mounted panels are permitted development provided they meet conditions broadly like these:

• Panels don't protrude more than 200mm from the roof surface.
• Panels don't extend above the highest part of the roof (excluding the chimney).
• Panels are set back, typically at least 1 metre from the external edges of the roof.
• The installation is on a building that isn't listed and isn't in a designated area (see below).

Meet those, and on an ordinary industrial, retail, office, or agricultural building you can usually proceed without a planning application — at essentially any system size now the 1MW cap is gone.

When you DO need planning permission

Permitted development rights fall away in these situations:

• Listed buildings. Any external alteration needs listed building consent, and panels on a listed building (or within its curtilage) will almost always require permission. Expect scrutiny.
• Conservation areas, National Parks, AONBs, World Heritage Sites. Designated areas restrict permitted development, especially where panels would be visible from a public highway. Check your building's status.
• Scheduled monuments. Off the table without consent.
• Ground-mounted arrays. Permitted development for ground-mount is far more limited — generally only small systems qualify, and anything beyond a modest size (commonly cited around 9m² / low kW) needs a full planning application. A field of panels is a planning project, not a permitted development.
• Wall-mounted panels facing a highway in sensitive locations, and other edge cases your installer or planning officer can flag.

If any of these apply, you'll need a planning application — typically determined in around eight weeks, and worth a pre-application enquiry with the council first.

The consents people forget (even when planning is fine)

Planning permission is not the only approval in play. Three others matter for commercial systems:

1. DNO grid connection (the big one). Before you can export — and often before you can install at commercial scale — you need approval from your Distribution Network Operator under the G99 connection process. This is entirely separate from planning. For larger commercial systems the DNO application can be the longest lead-time item in the whole project, sometimes months, and the DNO can require (chargeable) grid reinforcement. Start this early. A system that's permitted development can still be held up for months by the grid connection.

2. Building regulations / structural. Your roof has to safely carry the additional load. A structural survey confirms the roof can take the panels and mounting; this is a building-regs and safety matter, independent of planning. Don't assume an old roof is fine.

3. Building insurance and lease/landlord consent. Tell your insurer (it can affect cover), and if you lease, get landlord consent — see our guide to solar on a leased building.

Sanity-checking your own situation

Four quick questions tell you most of what you need:

1. Is the building listed, or in a conservation area / National Park / AONB? If yes, assume you need permission and check with the council.
2. Roof-mounted or ground-mounted? Roof on an ordinary building is usually permitted development; ground-mount of any real size usually isn't.
3. Does the install meet the conditions (under 200mm protrusion, not above the roofline, set back from edges)? If your installer wants to do something unusual, query it.
4. Have you started the DNO connection process? Whatever the planning answer, this is the consent most likely to delay you — begin it as soon as the project is real.

A competent installer will check planning status and handle the DNO application as part of their service. If a quote is silent on the grid connection, that's a question to ask before you sign — we cover it in reading a commercial solar quote.

The bottom line

For an ordinary commercial roof, planning is usually a non-issue since the 1MW cap was removed — the conditions are about how the panels sit, not how big the system is. The real gatekeepers are the exceptions (listed buildings, designated areas, ground-mount) and, more often, the DNO grid connection, which has nothing to do with planning and everything to do with your timeline.

To size a system for your building, run the calculator. For the financial side, see grants and funding. For monthly updates as the rules evolve, subscribe to the Brief.

General information, not planning or legal advice. Confirm your building's status with your local planning authority.