Do you need planning permission for commercial solar panels?

Planning is the question that worries businesses most before going solar, and for rooftop arrays it is usually the easy part. The rules changed in December 2023 to remove the old 1 MW cap, so size alone no longer triggers an application in England. What still matters is where the panels sit on the roof, what kind of building you have, and — separately — the grid connection. This guide separates the three, because they are often confused. When you want a number for your roof, the calculator gives you one in about a minute.

When you don't need planning permission

For most commercial buildings in England, rooftop solar is permitted development and needs no planning application — as long as the installation stays within the limits below. These are the conditions that keep an array inside permitted development.

If your roof meets all of these and the building is not protected (see next section), you can normally proceed without a planning application. It is still worth a quick check with your local planning authority, because protrusion and edge limits are easy to breach on an unusual roof.

The exceptions

Permitted development rights fall away — wholly or partly — for protected buildings and locations. If any of these apply, assume you need to check with your local planning authority before ordering anything:

• Listed buildings — listed building consent is needed as well as, in most cases, planning permission.
• Scheduled monuments — separate consent applies and rooftop solar is often not permitted at all.
• Conservation areas — permitted development is restricted, particularly for panels visible from a highway.
• Article 4 directions — a local authority can use an Article 4 direction to remove permitted development rights for an area, meaning a full application is required even where it otherwise would not be.

Flat-roof specifics

Flat roofs are common on commercial units and have one extra requirement worth flagging. The roof covering generally needs to achieve a BROOF(t4) fire rating — the standard that governs a roof's resistance to fire spreading across its surface — before panels go on. On a flat roof the 1m protrusion limit gives room for a tilted mounting frame, and keeping the array well inside the parapet line both satisfies the edge rule and reduces wind loading. Your installer should confirm the roof build-up meets the fire rating as part of the survey.

Building regs are not the same as planning

Even where no planning application is needed, building regulations always apply. They are a separate approval covering structural safety and electrical work, and they cannot be skipped on a commercial roof. In practice this means two things for your project:

A reputable installer treats both as standard. If a quote omits the structural survey, ask why — it is one of the line items a thin quote tends to drop. Our quote-comparison checklist lists the rest.

The grid side: G99 approval in 8–12 weeks

The part of a commercial solar project that most often sets the timeline is not planning at all — it is the grid connection. A system that exports to the grid needs approval from your distribution network operator under engineering recommendation G99, which typically takes 8–12 weeks. This is a connection consent, entirely separate from planning permission, and it is the single biggest reason to start early. SolarGridCheck maintains the definitive walk-through of the process, including what the DNO assesses and how export limits work:

Scotland, Wales and Northern Ireland differences

The permitted development rules above apply to England. The devolved nations run their own planning systems, and the thresholds for commercial rooftop solar differ.

In practice, Scotland and Wales broadly mirror England's approach — most commercial rooftop solar is permitted development — but each runs its own General Permitted Development rules and conditions, and Northern Ireland is different again. Confirm the current rules with your local planning authority before assuming permission is not needed.

Timeline: 5–9 months end to end

Putting the pieces together, a commercial rooftop project typically runs 5–9 months from first survey to commissioning. The panels themselves go up in days to a few weeks; the calendar is driven by design, the G99 application and scheduling. Because the grid approval runs in parallel with everything else, getting that application in early is the most effective way to shorten the whole project.

Updated June 2026 · By Taro Schenker, founder of Business Solar Check. We're independent — we don't install solar. Figures are indicative UK averages; your site survey confirms the numbers for your roof.