Permitted development in England
In England, solar panels on a dwellinghouse (a single house, not a flat) are permitted development under the Town and Country Planning (General Permitted Development) (England) Order 2015, as long as certain conditions are met.
The conditions include: the panels must not protrude more than 200mm from the roof surface or wall when installed; on a pitched roof, panels must not be higher than the highest part of the roof (excluding the chimney); on a flat roof, panels must be at least 1 metre from the edge; the installation must be removed when no longer needed; and in a World Heritage Site, panels must not be visible from a highway.
These conditions cover the vast majority of standard domestic installations. If your installer is MCS-certified, they will be aware of the permitted development limits and will flag anything that falls outside them.
When planning permission is required
Listed buildings require planning permission (and listed building consent) for solar panel installations in England, Wales, and Scotland. This applies regardless of how the installation is carried out — any alteration to a listed building's fabric requires consent. Some local authorities are sympathetic to discreet roof installations; others are not. Get pre-application advice from your local planning authority before commissioning a survey.
Conservation areas do not automatically require planning permission, but the visibility condition applies: panels in a conservation area must not be visible from a highway. In practice this means front-facing installations on road-facing elevations will usually require permission. Rear-facing installations on houses not directly overlooked from the road are typically permitted development.
Article 4 Directions can remove permitted development rights from specific areas or property types. Check with your local planning authority if you are in an area subject to an Article 4 Direction — these are sometimes applied to streets of historic character.
Flats and maisonettes
Permitted development for solar panels applies to dwellinghouses, not flats. If you own a flat (including a maisonette), permitted development rights do not apply, and you will need planning permission for any external solar installation.
In practice, solar installations on flats are relatively rare because roof rights and building regulations for communal roofs raise separate issues beyond planning. If you own or manage a block of flats and want to install solar, the planning application route is required, and you will need agreement from all freeholders or leaseholders with an interest in the roof.
Scotland, Wales, and Northern Ireland
Scotland has similar permitted development provisions but with some differences in the detail. The Scottish Government has generally been supportive of solar, and the conditions are broadly comparable to England.
Wales introduced updated permitted development rights for solar in 2023, expanding what is allowed without permission and explicitly aiming to support the transition to renewable energy. Welsh homeowners now have more flexibility than previously.
Northern Ireland operates under separate planning regulations. The principles are similar, but you should check with your local council or the Planning Portal Northern Ireland for current specifics.
If you are in any doubt — especially for a listed building, in a conservation area, or if your installation is in any way non-standard — contact your local planning authority for pre-application advice before proceeding. Most will respond within a few days and the advice is free.