Do solar panels on farm buildings need planning permission?

In England most rooftop solar on a non-domestic building such as a barn or shed is permitted development under Class J of Part 14 of the General Permitted Development Order 2015. Panels on a pitched roof must not stand more than 0.2 m proud of the roof slope, panels on a flat roof must not rise more than 1 m above the highest part of the roof, and nothing may sit within 1 m of the roof's external edge. Class J does not apply to listed buildings, buildings in the curtilage of a listed building, or scheduled monuments. Arrays above microgeneration size (50 kW) fall under Class J(c) and need a prior approval application about design and glare before work starts. Wales, Scotland and Northern Ireland have their own rules.

Is there still a 1 MW limit on permitted development for farm roofs?

No. The paragraph of Class J that capped rooftop capacity was omitted on 21 December 2023 by S.I. 2023/1279. What remains are the physical limits (0.2 m on pitched roofs, 1 m on flat roofs, a 1 m setback from the roof edge), the exclusions for listed buildings and scheduled monuments, and the prior approval step for arrays above 50 kW.

How much electricity does solar on a farm building generate?

It depends mostly on location and roof pitch. EU PVGIS data for a south-facing, rack-mounted array gives roughly 960-1,045 kWh per kWp a year on a 30-degree roof across England, falling to about 870 kWh in Aberdeen. A shallow 10-degree barn roof gives less — about 870-960 kWh per kWp in England — and produces around three quarters of its output between April and September.

Is there a grant for solar panels on farm buildings in England?

Not an open one at the moment. Round 2 of the Improving Farm Productivity grant, which paid 25% towards solar on farm building rooftops and irrigation reservoirs (minimum grant £15,000, maximum £100,000), is closed for applications according to gov.uk guidance updated on 2 March 2026. The Farming Equipment and Technology Fund's 2026 window closed on 12 May 2026. Capital allowances remain the main financial support.

What tax relief can a farm claim on solar panels?

Solar panels are special rate expenditure under section 104A(1)(g) of the Capital Allowances Act 2001. That means the Annual Investment Allowance (£1 million a year) can write the cost off in full, and companies can instead claim the 50% first-year allowance on new and unused special-rate assets bought from 1 April 2023, with the balance in the special rate pool at 6% a year. Full expensing is for main-rate assets, so it does not cover solar panels.

Will solar panels make a farm building liable for business rates?

Agricultural buildings used solely for agricultural operations are exempt from non-domestic rates in England and Wales under Schedule 5 of the Local Government Finance Act 1988. Separately, rating guidance excepts renewables plant from rateable value where most of the power is used on the premises (England from 1 April 2022 to 1 April 2035). Systems over 10 kW that mainly export are normally assessed as a separate hereditament — see our business rates guide.

Do farm building solar systems need a G99 application?

Almost always. G98 covers small systems up to 16 A per phase (about 3.68 kW on a single phase). Anything larger — which includes practically every farm building array — needs a G99 application to the distribution network operator before connection, and the DNO's response can take weeks or months.

Solar Panels on Farm Buildings UK: Roofs, Rules & Grants

Updated 26 September 2026. Published by SolarPanelsForFarms.uk (SEO Dons Ltd), an independent publisher: we don't install — quotes come from MCS-certified installers we match you with.

Most farms already own the best place in the parish for solar: big, south-facing roofs on buildings nobody wants to look at. Solar panels on farm buildings — barns, general-purpose sheds, grain stores, cubicle housing, poultry and pig units, packhouses — avoid the planning fight a field array faces, keep the land in production and put generation right next to the loads it feeds. The questions that decide a project are rarely about the panels. They are about the roof (its pitch, its sheeting and its frame), the planning route, the grid connection and whether the building is used in a way that lets you use the electricity yourself. This guide works through each one with current sources, so you can go into quotes knowing what a good answer looks like.

Which farm buildings suit solar panels?

Almost any agricultural building with a sound roof and a clear southerly aspect can take an array. What changes from one building to the next is how much of the roof is usable, what it is clad in and how its frame was designed.

Steel portal-frame sheds and grain stores

Wide, clear spans with profiled steel sheeting are the simplest host. Rail systems clamp to the profile or fix into the purlins — see fixing solar to metal farm roofs. Grain stores often carry the largest roofs on the farm, which is useful if drying and cooling loads sit alongside.

Dutch barns and older general-purpose buildings

Curved or shallow roofs and older, lighter frames need a structural check before anything is fixed. Many buildings of this era are clad in asbestos cement — a different job entirely (see below).

Livestock housing, dairy and poultry units

Continuous ventilation, lighting, milk cooling and water heating mean electricity is used through the day, which is what makes self-generated power worth the most. Ammonia in the building's air is the extra consideration for the panels themselves.

Listed barns and traditional stone buildings

Class J does not cover a listed building or a building within the curtilage of a listed building, so these need planning permission and, usually, listed building consent. A modern shed on the same holding is often the easier roof.

How much a farm building roof generates, region by region

Generation per kilowatt-peak (kWp) is the number that turns a roof into money, and it depends more on where the farm is and how steep the roof is than on the panel brand. The figures below come from the European Commission's PVGIS tool, queried for this guide on 26 September 2026 (SARAH3 satellite data 2005–2023, rack-mounted crystalline panels, 14% system losses, due south).

Location	10° barn roof (kWh/kWp/yr)	30° roof (kWh/kWp/yr)	June, 10° roof	December, 10° roof	Share Apr–Sep
Exeter, Devon	957	1,045	131	22	73%
Peterborough, Cambridgeshire	927	1,026	127	21	74%
Shrewsbury, Shropshire	881	963	124	18	74%
York, North Yorkshire	868	960	120	17	75%
Aberdeen, north-east Scotland	786	877	119	10	78%

Two practical lessons fall out of that table. First, a steeper roof earns roughly a tenth more over the year than a shallow one in the same place, so if a farm has a choice of buildings, the steeper south-facing roof usually wins. Second, the shallow roofs typical of portal-frame sheds concentrate their output into summer: a 10° roof near York makes 120 kWh per kWp in June and just 17 in December. A 50 kWp array on that roof would produce about 43,400 kWh over a year (50 × 868), most of it between April and September. That suits a farm whose heaviest loads are in the summer half — ventilation, cooling, irrigation, early harvest drying — far better than one whose peak is a winter lambing shed. For the month-by-month picture and what it means for self-consumption, see whether solar panels can power a whole farm.

The roof: structure, sheeting and the survey

A farm building was designed for the loads its builder expected — sheeting, snow and wind — not for a layer of panels, rails and the people who fit them. Before a quote becomes a contract, the installer should confirm three things in writing: that the frame and purlins can take the added dead load and the wind uplift on the array; how the rails will fix to the sheeting or purlins without creating leak paths; and how the roof will be accessed safely during installation and for maintenance afterwards.

Safe access is a legal point, not a courtesy. Regulation 9 of the Work at Height Regulations 2005 requires employers to stop anyone working on or near a fragile surface where the work can reasonably be done another way, and otherwise to provide suitable platforms, coverings, guard rails or similar protection. Fibre-cement sheets and roof lights are the classic fragile surfaces on farm buildings, which is why a professional plan will talk about stagings, netting or edge protection rather than "walking the purlin lines".

Asbestos cement roofs

Many post-war farm buildings are clad in asbestos cement (AC). HSE's task sheet a14 on removing AC sheets is blunt: "AC roofs are always fragile and cannot bear weight", and it tells workers to avoid drilling through AC. That rules out treating an AC roof like a steel one. The realistic routes are to overclad the old sheets with non-asbestos sheeting fixed to the existing purlins (HSE describes this overlay approach), to remove the AC and re-sheet before the solar goes on, or to put the array on a different roof. Removing intact AC sheets on a small scale is normally non-licensed work; if the sheets break up and create significant dust, HSE classes it as notifiable non-licensed work, and large-scale removal needs a full risk assessment and plan of work. Farm buildings are non-domestic premises, so the duty to manage asbestos under regulation 4 of the Control of Asbestos Regulations 2012 also applies. Our full guide covers the options for solar panels on asbestos roofs.

Livestock buildings and ammonia

Ammonia from manure and slurry is corrosive, and modules on or near animal housing are exposed to it for decades. The international test for this is IEC 62716:2013, "Photovoltaic (PV) modules – Ammonia corrosion testing". TÜV Rheinland, which certifies to it, describes it as relevant to the roofs of livestock buildings: 20 test cycles over 480 hours, passing only if the module shows no obvious visual defects and loses no more than 5% of maximum output. Ask for the certificate for the exact module model on the quote. Our guide to agricultural solar panels explains which certifications matter and why.

Planning permission for solar on farm buildings (England)

In England, rooftop solar on a non-domestic building is permitted development under Class J of Part 14 of the General Permitted Development Order 2015. The householder rules people quote (Class A) do not apply to a barn. Under Class J, development is not permitted if:

• panels on a pitched roof would protrude more than 0.2 m beyond the plane of the roof slope;
• panels on a flat roof would rise more than 1 m above the highest part of the roof;
• any equipment would sit on a roof within 1 m of its external edge;
• the building is listed, is within the curtilage of a listed building, or the site is a scheduled monument.

Two points catch people out. The old capacity cap on rooftop permitted development was omitted on 21 December 2023 (S.I. 2023/1279), so a large array can still be permitted development. But Class J separates "microgeneration" solar — up to 50 kW, as defined in section 82 of the Energy Act 2004 — from "other solar PV equipment on the roof of a building", and that larger category, which covers most farm-scale arrays, needs a prior approval application to the local planning authority about design and external appearance, "in particular the impact of glare on occupiers of neighbouring land", before work starts. Every Class J installation must also be sited, so far as practicable, to minimise its effect on the building's appearance and be removed when no longer needed. Ground-mounted panels are a different class altogether: Class K allows only a single stand-alone unit of up to 9 m², no more than 4 m high and at least 5 m from the boundary, so a field array needs planning permission. Our farm solar planning guide covers applications in more depth.

The grid connection

Connection is often the longest lead item. Engineering Recommendation G98 covers small generators up to 16 A per phase — about 3.68 kW on a single phase — and those are notified after installation. Practically every farm building array is larger, so it needs a G99 application to the distribution network operator before it is connected, and the DNO may impose an export limit or ask for reinforcement. Starting the application early, alongside the structural survey, protects the programme. See G98 and G99 explained for farm solar.

Grants, tax relief and business rates in 2026

Grants (England). The Improving Farm Productivity grant paid 25% towards solar PV on farm building rooftops and irrigation reservoirs — a minimum grant of £15,000 (25% of £60,000) and a maximum of £100,000 per business — and excluded ground-based arrays and north-facing or heavily shaded roofs. Round 2 is closed for applications (gov.uk guidance updated 2 March 2026), and the Farming Equipment and Technology Fund's 2026 window closed on 12 May 2026. Check gov.uk for any future round before budgeting a grant into a farm-building project; our farm solar grants page tracks the schemes in each nation.

Tax relief. Solar panels are special rate expenditure under section 104A(1)(g) of the Capital Allowances Act 2001. The Annual Investment Allowance — £1 million a year for sole traders, partnerships of individuals and companies — can relieve the full cost in the year of purchase. Companies can instead claim the 50% first-year allowance on new and unused special-rate assets bought from 1 April 2023, with the rest going into the special rate pool at 6% a year. Full expensing applies only to main-rate assets, so it is not available for solar panels.

Business rates. Agricultural buildings used solely in connection with agricultural operations are exempt from non-domestic rates in England and Wales under Schedule 5 of the Local Government Finance Act 1988. The government's Rating Manual (updated 11 May 2026) excepts renewables plant from rateable value where the majority of the power is used on the premises, from 1 April 2022 to 1 April 2035 in England and from 1 April 2024 in Wales, while a system over 10 kW that mainly exports "will normally constitute a separate hereditament". What that means for a farm roof is set out in our guide to business rates on solar panels on farm buildings.

What a good quote for a farm building should show

1. The roof, identified precisely — building, sheeting type, pitch and orientation, and whether it contains asbestos (with the survey result, not an assumption).
2. A structural statement — who checked the frame and purlins, against what loads, and any strengthening required.
3. The planning route — Class J permitted development, a Class J(c) prior approval for arrays above 50 kW, or a full application for listed or ground-mounted schemes.
4. The grid route — G98 or G99, the DNO, any export limit, and who pays for reinforcement.
5. Module certifications — including IEC 62716 for livestock buildings and IEC 61701 salt-mist testing for coastal farms.
6. Generation and self-use — a yield estimate that reconciles to PVGIS for your postcode and a self-consumption figure built from your half-hourly meter data.

Solar Panels on Farm Buildings