Planning Rules for Garden Solar Panels
Garden solar sits under planning rules that are genuinely permissive — and genuinely specific. This page sets out the English permitted development position for each mounting type, flags where the other UK nations differ, and ends with the one step that beats reading any website: asking your council, in writing, before you spend.
Stand-alone ground arrays: the tight one
In England, a stand-alone solar installation in a garden is often permitted development — but the conditions are the tightest in domestic solar, and all of them must hold. It must be the first stand-alone installation within the property's curtilage (the allowance is for one). No part may exceed four metres above ground. It must sit at least five metres from every boundary of the curtilage. The panel area must not exceed nine square metres, with no single dimension over three metres. And the protective designations bite: within the curtilage of a listed building, stand-alone solar PD generally falls away entirely, while in conservation areas the array must not be nearer a highway than the house. Miss any condition and you are not in a grey zone — you need planning permission, full stop.
The five-metre boundary rule deserves emphasis because it disqualifies more gardens than the area cap. A garden ten metres wide has, at most, a zero-width strip that qualifies. Where PD fails, the consent route is unglamorous but reliable: a householder application (£258 in England), drawings showing siting and heights, and a case officer who mostly cares about neighbour amenity and street scene. Garden arrays of 3–5kWp are approved routinely; the eight-week determination period is the real cost, so start it before ordering anything. Full design detail for this route lives on the ground array page.
Panels on garden buildings: the generous one
Solar mounted on a shed, garage, garden room, or other outbuilding is treated like roof solar on the house: often permitted development provided panels project no more than 200mm from the roof or wall surface, do not sit higher than the highest part of the roof (excluding chimneys), and the listed-building and conservation-area conditions are respected. There is no nine-square-metre cap on this route — which produces the useful quirk that a large shed roof can lawfully carry more PD solar than the lawn beside it. The catch is that the building itself must be lawful: an outbuilding that crept over its own PD limits when built cannot launder panels into legitimacy. If the garden room went up without the scrutiny it needed, resolve that first.
Pergolas and canopies: the ambiguous one
A solar pergola is assessed both as a garden structure (height limits: typically 2.5 metres within two metres of a boundary, more further in) and as a solar installation, and councils differ on which lens leads. Because the structure exists to carry the panels, some authorities read it as a stand-alone solar installation and apply the nine-square-metre logic; others treat it as an outbuilding with panels on top. This is the one garden solar route where we recommend a written LPA view as standard practice rather than caution — a short pre-application enquiry, often free for householders, settles it before steel is ordered.
Wales, Scotland, Northern Ireland — and the catches everywhere
Wales runs a similar PD framework with its own measurements; Scotland's regime differs more substantially, particularly on stand-alone installations; Northern Ireland's differs again. If you are outside England, treat every figure above as illustrative only. And in all four nations, three catches override the general rules: Article 4 directions (councils can strip PD rights street by street), planning conditions on your own house's original consent (common on newer estates — check your deeds pack), and restrictive covenants, which are a legal matter rather than planning but sting identically. None are exotic; all are findable in an afternoon.
How to actually confirm
Email your Local Planning Authority's duty planner with a one-page sketch: array or structure position, dimensions, distances to boundaries, and a note of any designations. Ask whether they consider the proposal permitted development, and keep the reply. For certainty that survives a house sale, a Lawful Development Certificate (around £129 for a proposed use in England) turns "we think so" into a document. It is rarely necessary for a four-panel array — but for a pergola, or anything near a boundary dispute, it is the cheapest insurance in the project. Then the fun part: budgets on the costs page, and a sense-check of your whole plan via the contact form whenever you want one.