Do I Need Planning Permission for Solar on Agricultural Buildings? (2026 Guide)

For the overwhelming majority of UK farms, the honest answer is no — rooftop solar on an agricultural building is almost always Permitted Development and does not need a full planning application. The general guidance you’ll find from bodies like the NFU is broadly correct but stops short of the detail that actually decides your project, so this guide goes further: the exact legal route, the specific conditions you must meet, and the precise circumstances where a planning application genuinely is required.

The short answer: rooftop PV is usually Permitted Development

Most farm rooftop solar installations are carried out under Permitted Development (PD) rights, meaning you do not submit a planning application — provided you meet the conditions set out in legislation. The relevant route for the building itself is Class A, Part 14 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015 (“the GPDO 2015”), which covers the installation, alteration or replacement of microgeneration solar PV or solar thermal equipment on a building.

This is the part most general guides gloss over. PD is not a blanket permission — it is a set of rights that exist only while you stay inside specific limits. Break a condition and your installation is unlawful, exposing you to enforcement. Get it right and you save weeks of waiting and a planning fee.

Class A, Part 14 GPDO 2015: the conditions that apply

Under Class A, Part 14, solar equipment on a building (including agricultural buildings such as barns, grain stores and dairy parlours) is permitted development if you observe the following:

• No part of the equipment may protrude more than 0.2m beyond the plane of the roof slope when measured perpendicular to that slope. Standard flush-mounted panels on a pitched roof comfortably meet this.
• The equipment must not be installed on a wall or roof slope that fronts a highway where the building is in a Conservation Area or World Heritage Site.
• The equipment must, so far as practicable, be sited to minimise its effect on the external appearance of the building and on the amenity of the area.
• Equipment no longer needed for microgeneration must be removed as soon as reasonably practicable.

These are genuinely achievable on a typical steel-portal or fibre-cement farm roof. The “minimise the effect on amenity” condition is a duty, not a discretionary planning judgement — you don’t apply for it, you simply comply with it.

The 1 MW cap — the December 2023 change everyone misses

The single most important recent change is the 1 MW capacity ceiling. Since amendments that took effect in December 2023, rooftop solar on commercial and agricultural buildings in England can be installed under Permitted Development up to 1 megawatt (1 MW) of installed capacity — a significant uplift from the previous restrictive thresholds that effectively capped larger systems.

For most farm buildings this removes the cap as a practical barrier: a 1 MW array is enormous (roughly 5,000–6,000 m² of roof), far larger than a single typical barn roof. If you are roofing out an entire range of buildings, however, keep total installed capacity per building in mind — this is exactly the kind of scale where a specialist should design and document the system. Our overview of solar panels for agricultural buildings sets out how multi-roof schemes are sized and connected.

When you DO need full planning permission

PD rights are switched off, restricted or overridden in several situations. If any of these apply, assume you need a planning application — and confirm it with your local planning authority (LPA) before you order panels.

• Listed buildings. A listed farmhouse, listed barn or building within the curtilage of a listed building requires Listed Building Consent for solar, and usually planning permission too. This is the firmest “stop” in the whole framework — do not rely on PD.
• Conservation Areas and World Heritage Sites. PD is restricted: you cannot use the front-facing roof slope facing a highway, and an Article 4 Direction may remove PD rights altogether.
• AONBs (National Landscapes), National Parks and the Broads. These “Article 2(3) land” designations attract tighter control, and LPAs frequently use Article 4 Directions to strip out PD. Always check whether an Article 4 Direction covers your holding.
• Ground-mounted (standalone) solar. This is a different route — Class A, Part 14 also permits standalone solar but only within strict size limits: no more than 9m wide, 9m deep and 4m high, sited at least 5m from any boundary, and not within the curtilage of a listed building. Anything beyond a single small array of this size needs planning permission. A commercial-scale ground array on farmland is a full planning matter (and often an EIA screening one).
• Breaching any Class A condition — for example panels protruding beyond 0.2m, or a front-facing array in a Conservation Area.

If a building’s roof is also being replaced — common where ageing fibre-cement sheets contain asbestos governed by the Control of Asbestos Regulations 2012 — a combined re-roof plus solar approach can be the cleanest path, and most re-roofing work is itself PD.

Scotland and Wales: the rules differ

The GPDO 2015 applies to England only. The devolved nations run their own regimes:

• Scotland. Permitted development is governed by the Town and Country Planning (General Permitted Development) (Scotland) Order 1992 as amended. Roof-mounted solar on non-domestic buildings is broadly PD subject to similar conditions, but designations and projection limits differ — check with your Scottish LPA.
• Wales. Permitted development sits in the Town and Country Planning (General Permitted Development) Order 1995 as it applies to Wales, amended by Welsh Government. Again, rooftop solar is largely PD with conditions, but the thresholds and the treatment of designated land are not identical to England’s 1 MW position.

The practical takeaway: never assume an English threshold applies north of the border or in Wales. Confirm the position with the relevant authority.

Prior approval and grid: the steps that come before installation

Even where solar itself is full PD, two procedural steps commonly apply.

Prior approval. For certain larger or sensitive installations, the GPDO requires you to apply to the LPA for a determination as to whether their prior approval is needed — typically for the design and external appearance, or siting. This is lighter and faster than a full planning application but is not optional where the legislation specifies it.

Grid connection. Separately from planning, any grid-connected system must satisfy your Distribution Network Operator. Systems are connected under engineering standard G98 (small) or G99 (larger commercial arrays), and a farm-scale system will almost always require a formal G99 application and connection offer. Equipment should be MCS-certified so the installation qualifies for the Smart Export Guarantee (SEG), which currently pays roughly 8–15p/kWh for exported electricity — useful, though the real prize is offsetting grid import at around 25–28p/kWh.

The numbers behind doing it properly

Planning compliance is only step one; the financial case is what makes farm solar compelling. Capital allowances are central: solar qualifies for the 100% Annual Investment Allowance (AIA) — letting you write off the full cost (within the £1m AIA limit) against taxable profits in the year of purchase. See our breakdown of the 100% AIA on farm solar, and our guides to cost and grants and funding for the wider picture. For farms preferring zero capital outlay, a PPA for farms is an alternative route.

Whether you run a dairy parlour with high daytime base load or a grain store needing summer drying power, getting the planning route right keeps the project lawful and the returns intact. If you want certainty rather than a best guess, a specialist who installs across the agricultural sector will confirm your PD position in writing before any work begins — that’s what proper solar panels for agricultural buildings projects look like.

Ready to confirm your planning route and size a system for your roof? Get a free, no-obligation quote.