Solar on farm buildings: permitted development limits

Solar on farm buildings permitted development rights sit in Part 14 of Schedule 2 to the General Permitted Development Order 2015, not in Part 6. That distinction catches people out every season. Part 6 is the agricultural rights, and it covers buildings and operations reasonably necessary for agriculture on the holding. Part 14 is the microgeneration rights, and it is Part 14 that lets you put panels on a grain store roof or a turbine in a yard. Confuse the two and you either submit a prior notification that the council cannot determine, or you build something with no lawful cover at all.

The purpose test is where the two parts meet, and it is the test that decides most rural renewables questions.

Which rights cover which installation

Part 14 divides microgeneration by whether the premises are domestic or not, and by whether the equipment sits on a building or stands alone.

Class J has been amended more than once, and the capacity ceiling for rooftop installations on non-domestic buildings has been relaxed since the Order was made. Read the current consolidated text of Part 14 on legislation.gov.uk before you rely on any figure, because secondary guidance and trade summaries lag behind the amendments.

Class K is the one that disappoints people. A standalone non-domestic array is held to a small panel area and a low overall height, and only one standalone installation is permitted within the curtilage. It is a right for a single array powering a building, not a route to a field of panels.

The purpose test and the agricultural use requirement

Part 6 Class A permits agricultural development on a unit of five hectares or more, provided the development is reasonably necessary for the purposes of agriculture within that unit. Part 6 Class B covers smaller units of between 0.4 and five hectares, with tighter limits.

Energy generation is not agriculture. A building erected under Part 6 to house generating plant, or a hardstanding laid under Part 6 for an array, is outside the purpose test and the right does not apply. The same reasoning bites where the output is mostly exported. If the installation primarily serves the grid rather than the holding, the argument that it is reasonably necessary for agriculture becomes very hard to run.

Part 14 does not carry an agricultural purpose test in those terms, which is why it is the right place to look. What Part 14 does carry is a requirement that the equipment is used for microgeneration, together with a condition that it be removed as soon as reasonably practicable when no longer needed for that purpose. That condition travels with the installation and the council can enforce it.

Where you do want a Part 6 building, the familiar limits apply. The ground area covered must not exceed 465 square metres, the height is capped at 12 metres and at 3 metres within three kilometres of an aerodrome, and nothing may sit within 25 metres of the metalled part of a trunk or classified road. Significant Part 6 development needs a prior notification to the council for a determination as to whether its prior approval of siting, design and external appearance is required.

Where a full application starts

The honest line for most farm renewables schemes of any scale is that permitted development will not reach them.

A ground-mounted array beyond the Class K limits, a turbine above the Class H envelope, a battery storage compound, a biomass boiler house or an anaerobic digestion plant all need planning permission. So does a building whose main purpose is to house generating or storage equipment, however agricultural the setting looks.

The threshold questions for a larger scheme are the ones a planning officer will ask in the first meeting. What is the land classified as, because the loss of best and most versatile land weighs against development and an Agricultural Land Classification survey is the way that is answered. What is the landscape designation. Where is the grid connection. And what happens at the end of the operational life.

Grid connection is a separate consent and a real constraint

Panels without a connection are an expensive roof covering. The grid connection is a separate exercise from planning, handled through a connection application to the distribution network operator, and its cost and timescale are frequently the thing that kills a rural scheme.

Two planning points follow. First, the connection infrastructure may need its own consent. Underground cables and substations are often covered by the electricity undertaker rights in the Order, but a new overhead line can require consent under section 37 of the Electricity Act 1989, and a substation compound on a designated site can need permission in its own right. Second, export capacity is not a planning matter, so a permission tells you nothing about whether you can sell the power. Get an indicative connection offer before you commission any planning documents.

Where a scheme is designed around heat rather than power, our note on safeguarding a future heat network connection sets out how to keep the option open at design stage. For combustion plant the air quality position matters more than the planning class, and our piece on biomass boilers in a smoke control area covers the overlap with environmental protection law.

Designated land, listed buildings and Article 4

Part 14 rights are restricted on designated land, meaning conservation areas, National Parks, the Broads, National Landscapes and World Heritage Sites. Restrictions typically bite on the wall or roof slope facing a highway, and on standalone installations visible from a highway. Read the specific class conditions rather than assuming a blanket ban.

Panels on a listed building are a separate matter entirely. Permitted development rights do not remove the need for listed building consent, and fixing an array to the roof of a listed barn will usually require it. Expect the conservation officer to ask about fixings, reversibility, the visibility of cable runs and whether a less visible roof slope would work.

Article 4 directions can remove Part 14 rights in a defined area. Check the council's Article 4 register before you order equipment, because the direction will not be on the deeds.

Glint, glare and the highway

Two technical objections recur on farm arrays, and both are answerable.

Glint and glare matters where an array sits near an aerodrome, a railway or a road on an alignment that puts reflected light into a pilot's or driver's eye. Aerodrome safeguarding consultation is triggered by proximity to a safeguarded airfield, and a glint and glare study using the panel geometry and the sun path is the standard answer. The Civil Aviation Authority publishes the safeguarding framework.

Highway objections are usually about the access rather than the array. A field access that was adequate for a tractor twice a season may not be adequate for construction deliveries, and the highway authority will say so. Deal with the construction phase explicitly, including the swept paths at the junction and any temporary passing bays.

Conditions, aftercare and tying the installation to the holding

Permitted development under Part 14 comes with the removal condition described above. A planning permission for a larger scheme will come with more.

Expect a decommissioning condition requiring removal and restoration within a defined period after generation ceases, a landscape and biodiversity scheme, a construction management plan, a condition fixing the panel height and the layout as approved, and on some sites a requirement to retain agricultural use between and beneath the rows. Where the land is let, make sure the tenancy and the planning obligation do not contradict each other on who removes what.

Councils increasingly ask for an Energy Statement that sets out the generation case against local plan policy rather than a generic benefits list, and for an honest account of how much of the output serves the holding.

PlanScope can draft the planning statement, energy statement and supporting documents for a farm renewables scheme, structured to UK planning policy, with flags where your own yield figures, connection offer and land classification need to go in. Enter your postcode on PlanScope to see which reports a rural site is likely to need. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.

This is general guidance, not legal advice. A lawful development certificate is the only formal way to confirm that works are lawful, so check the position with your local planning authority or a qualified professional before relying on permitted development rights.