Planning is one of the first questions on any commercial solar project — and since a rule change in late 2023, the answer in England is usually better than people expect. Here’s the position, and where the exceptions still bite.
Rooftop solar is usually permitted development
In England, solar on the roof (or walls) of a commercial building falls under permitted development rights — meaning no planning application, provided the installation meets the conditions. The significant change came in December 2023, when the Government removed the previous 1MW capacity cap for rooftop solar on non-domestic buildings. Large warehouse, factory and distribution roofs — exactly the buildings with the best solar potential — can now be fully panelled under permitted development.
The physical conditions that remain are straightforward: on a pitched roof, panels must not protrude more than 0.2m beyond the plane of the roof slope; on a flat roof, the highest part of the installation must sit no more than 1m above the highest part of the roof (excluding chimneys); and no equipment may sit within 1m of the roof edge. Comfortable limits for the tilted mounting frames flat-roof arrays actually use.
One step many guides miss: for rooftop solar above 50kW (which is most commercial systems), permitted development comes with a prior approval requirement — a light-touch application to the local planning authority covering design, external appearance and in particular the impact of glare on neighbours. It is not a planning application, but it is a formal step with a response window, and we build it into the programme from day one.
The exceptions that still apply
Permitted development is conditional, and a handful of situations still require an application:
- Listed buildings — always require consent.
- Conservation areas and other designated land — additional restrictions apply, particularly for installations visible from a highway.
- Physical conditions — panels must not protrude beyond the limits above or extend past the roof edge; installations must be removed when no longer needed.
- Ground-mounted arrays at commercial scale normally require a full planning application — permitted development for stand-alone solar is limited to very small installations.
None of these rule a project out; they change the route. Novalux has delivered projects across the UK through both permitted development and full applications — including farm and agricultural sites where ground-mount and rooftop combine.
Wales has its own rules — and they’re also generous
The rules above are England’s. Wales runs its own permitted development regime for non-domestic solar, and — contrary to plenty of stale guides still circulating — Wales removed its output threshold back in April 2019, so there is no capacity cap on commercial rooftop solar in Wales either. The physical limits are similar: no more than 20cm protrusion beyond a wall or pitched-roof plane, a 1m height limit on flat roofs, nothing within 1m of the roof edge, and listed buildings and scheduled monuments excluded.
Two Welsh conditions to know: permitted development for solar does not apply within 3km of an airport or aerodrome perimeter, and every installation must be sited, so far as practicable, to minimise glint and glare. With our head office in Monmouthshire we work on both sides of the border daily, and we confirm the applicable regime for every site as part of the design stage.
Carports, ground-mount and solar farms
Since December 2023, England also has a permitted development class for solar canopies on non-domestic car parks — up to 4m high, with prior approval covering siting, appearance and glare. It’s the route that makes solar carports with EV charging quick to consent.
Ground-mounted arrays are different: standalone permitted development is capped at a token 9m² in both England and Wales, so any commercial ground-mount system goes through a full planning application — which we prepare and submit as part of the project.
At solar-farm scale the consenting regimes changed recently in both nations: since 31 December 2025, England’s nationally-significant-infrastructure threshold sits at 100MW (up from 50MW), so ground-mount below that is decided by the local planning authority; and since 15 December 2025 Wales consents generating stations of 50–350MW as Significant Infrastructure Projects through the Welsh Ministers, with anything smaller handled locally. In practice: virtually every commercial and farm-scale project, rooftop or ground-mount, is a local decision.
Other consents worth knowing about
Planning is not the only consent on a commercial project. The DNO grid connection is a separate approval with its own timeline — usually the longer of the two — and buildings with unusual roof structures need a structural assessment before design is finalised. We run all three in parallel from day one so none of them becomes the critical path.
Checked for your site, not assumed
Every Novalux proposal states the consent route for your specific building — permitted development or application, England or Wales — before you commit, alongside the tax relief that applies and what the system will cost. Request a Quick Quote and we’ll include it.