How far can solar panels protrude from a pitched roof without planning permission?

That single measurement is the one householders check before ordering, because it is the limit most domestic arrays breach when they are mounted on tilted frames rather than fixed flush. It is also the limit that changes shape depending on where the property is: England, Scotland, Wales and Northern Ireland each set their own version, and conservation areas, listed buildings and Article 4 Directions can remove the right altogether.

The short answer: 200mm from a pitched roof slope

For a house with a pitched roof, the permitted development position is that the equipment does not stick out more than 0.2 metres from the roof slope⁷. Guidance for a block of flats uses the same figure, with panels projecting no more than 200mm from the wall surface or, where relevant, the roof slope¹. Local authority guidance repeats it in the same terms: roof-mounted panels and equipment should project no more than 200mm from the roof slope or wall surface⁸.

The limit is not a planning judgement about appearance. It is a fixed threshold written into the permitted development classes, and it applies to the equipment and its mountings together. A panel fixed flush to the roof covering sits far inside it. A panel on a raised frame, or one tilted to improve the angle to the sun, is the case where the measurement starts to matter.

The figure is consistent across England, Wales and Northern Ireland in its domestic form. Northern Ireland's legislation states that development is not permitted if any part of the solar PV or solar thermal equipment would protrude more than 20 centimetres beyond the plane of any existing roof slope which faces onto and is visible from a road⁵. The same 20 centimetre road-facing figure appears in the Northern Ireland rules for roof-mounted equipment⁹. Wales uses 20 centimetres beyond the plane of the wall or the roof slope, measured from the perpendicular with the external surface¹⁰.

Scotland takes a different approach for curtilage buildings, with a 500 millimetre limit from the outer surface of an external wall, roof plane, roof ridge or chimney under Class 6HB¹¹. That is a separate class from the domestic house rules and applies to buildings within the curtilage of a dwelling, so a Scottish householder checking an outbuilding or an ancillary structure is working to a different number from the 200mm that governs the house itself.

How the 200mm limit is measured

The measurement is taken perpendicular to the external surface of the roof slope or wall, not vertically from the ground and not along the pitch of the roof. Guidance for Southampton states that panels would breach the limit if they project more than 200mm from the roof slope or wall surface when measured perpendicular with the external surface³. Brighton and Hove uses the same construction: more than 200mm from the roof slope or wall surface when measured perpendicular to the external surface¹².

That perpendicular measurement is what makes the limit practical rather than theoretical. It is the distance from the plane of the existing roof covering out to the furthest point of the panel and its fixings. A mounting system that lifts the panel clear of the roof surface, with a panel frame adding further depth, stays inside the limit only while the total stays under 200mm. A frame designed to tilt the panel away from the roof to catch a better angle can push the outer edge past 200mm, particularly at the top of the array.

Local authority guidance across England repeats the same wording, which is a useful check that the figure is not a local variation. Bedford's advice note states panels should project no more than 200mm from the roof slope or wall surface¹³. Camden's guidance uses the identical perpendicular construction¹⁴. Hart's technical advice note states that equipment must not protrude more than 0.2 metres beyond the plane of the wall or, in the case of a pitched roof, the roof slope, measured from the perpendicular with the external surface¹⁵.

The height condition sits alongside the projection limit and is measured differently. Panels should not be installed above the highest part of the roof, excluding the chimney¹. On a flat roof the measure changes again: panels must not exceed 60cm above the highest part of the roof, excluding the chimney⁴, and a separate Welsh figure states that flat-roof panels cannot protrude more than 1 metre above the plane of the roof¹⁶.

When panels may protrude further: conservation areas and exceptions

Conservation area status does not by itself raise the 200mm figure, but it changes which rules apply and, in some places, removes the permitted development right entirely. West Northamptonshire's guidance states that planning permission is required for the erection of solar panels on roofs where they project more than 20cm from the roof plane, or on walls facing the highway, or on listed buildings or within their curtilage, including stand-alone solar panels¹⁷. The 20cm threshold is the same number, applied as the point at which consent is needed rather than as a permitted development allowance.

Where permitted development has been extended in conservation areas, the figures used in proposals are much larger. A Scottish consultation on domestic permitted development used 1 metre from the outer surface of the wall or roof, including associated mountings, as the conservation area limit¹⁸. An earlier Scottish consultation used the same 1 metre figure¹⁹. Scottish circular guidance describes Class 6HA, under which no part of the solar panel equipment may protrude more than 1m from the surface of the wall, roof plane, roof ridge or chimney²⁰. Class 6J for non-domestic buildings uses the same 1 metre limit from the surface of the building⁶.

These larger figures are not a general allowance for a house in a conservation area in England. They belong to specific classes and specific national frameworks, and a householder reading a 1 metre figure needs to check which class it comes from before relying on it. The safest reading is that 200mm remains the domestic baseline, and that conservation area status is a prompt to check the local position rather than a reason to expect a larger limit.

Local Listed Building Consent Orders show how a local authority can set its own condition. The Royal Borough of Kensington and Chelsea order requires that the solar equipment would protrude no more than 0.2 metres beyond the plane of the roof when measured from the perpendicular with the external surface of the roof, unless agreed otherwise in writing by the local planning authority²¹. Southwark's proposed order uses the same 0.2 metre figure, stating that the solar panels will not protrude more than 0.2 metre beyond the plane of the roof when measured from the perpendicular²².

Outbuildings: a different protrusion limit

Solar panels on a garage, shed or other outbuilding are governed by separate classes, and the figures diverge more here than anywhere else in the rules. Scottish legislation sets a 500 millimetre limit: solar panels may not protrude more than 500mm from the wall or roof of the outbuilding they are attached to⁶. Scottish consultation material on domestic permitted development for outbuildings uses 200mm from a wall or pitched roof, and 500mm from the surface of a flat roof¹⁸. An earlier consultation used the same 200mm figure for a wall or pitched roof of an outbuilding¹⁹.

In England, the Planning Portal describes a different set of figures for walls, balconies and roof enclosures. On a wall, balcony or roof enclosure which abuts a highway, the solar PV should not protrude more than 0.2 metres beyond the plane of the wall, and on any other wall, balcony or roof enclosure it should not protrude by more than 0.4 metres¹. Those figures apply to the rules following 27 August 2026 and cover structures that are not the main pitched roof of the house.

The domestic class in England and Wales states that the equipment would not be permitted if it would protrude more than 0.2 metres beyond the plane of the wall or the roof slope when measured from the perpendicular with the external surface of the wall or roof slope². That is the general domestic figure, and it is the one to work from unless a specific class for the structure in question gives a different number.

Conditions that must be met alongside the protrusion limit

The projection figure is one condition among several, and an array that meets it can still fall outside permitted development on another ground. The height condition is the most commonly missed: panels should not be installed above the highest part of the roof, excluding the chimney¹. A panel that clears the ridge, even by a small amount, fails that test regardless of how little it projects.

The road-facing condition is the second. Northern Ireland's rules state that development is not permitted if any part of the solar PV or solar thermal equipment would protrude more than 20 centimetres beyond the plane of any existing roof slope which faces onto and is visible from a road⁵. The same 20 centimetre road-facing figure appears in the Northern Ireland domestic class⁹ and in the Northern Ireland legislation for roof-mounted equipment²³. A roof slope that faces a road is therefore subject to a stricter reading than one that faces a garden.

For non-domestic buildings the capacity limits sit alongside the projection limit. Permitted development rights exist for non-domestic solar panels up to 45kw electricity or 50kw thermal²⁴. Non-domestic permitted development rights do not apply within 3 kilometres of the perimeter of an aerodrome or technical site¹⁶. Proposed non-domestic rights have also used an edge condition, with equipment not to be located on the roof closer to the edge of the roof than the height of the installed equipment²⁵, and a proposed 1 metre limit from the roof excluding chimneys or other roof features²⁵.

When permitted development rights do not apply

Permitted development is withdrawn in several situations, and in each of them the 200mm figure stops being a threshold and becomes irrelevant to whether consent is needed. An Article 4 Direction is the clearest case. Where one applies, planning permission is required to install solar panels, and directions of this kind cover specific areas such as Bishopstone Conservation Area and the Swindon Railway Village Area²⁶. Southampton's guidance states that buildings in conservation areas covered by Article 4 Directions which remove permitted development rights for roof alterations may require planning permission³.

Article 4 Directions are site-specific, so the only reliable check is with the local planning authority for the address. A direction covering one conservation area or one historic estate has no effect on a neighbouring parish, and a householder cannot infer the position from the general conservation area rules. The Article 4 Directions page sets out how they are made and what they withdraw.

Listed buildings are the other main exclusion. West Northamptonshire's guidance states that planning permission is required for solar panels on listed buildings or within their curtilage, including stand-alone panels¹⁷. Local Listed Building Consent Orders can grant consent for specified works without a separate application, but they come with their own conditions, including the 0.2 metre projection condition used in the Kensington and Chelsea order²¹ and the same figure in Southwark's proposed order²².

Where permitted development does not apply, the application route is the same as for any other householder project, and the projection figure becomes one of the design matters a planning officer weighs rather than a fixed pass or fail. The wider framework is set out in Permitted Development Rights for Home Energy Equipment and in Listed Buildings and Conservation Areas.