Ground-mounted solar and best and most versatile land

A ground-mounted solar scheme on grades 1, 2 or 3a agricultural land is making a policy argument it does not have to make. Those grades are the best and most versatile land, and national policy expects their economic and other benefits to be taken into account, with poorer quality land preferred where development of agricultural land is shown to be necessary. Everything that follows in an application flows from where the site sits in that classification, which is why the survey comes before the layout.

The provisional mapping is not the answer. It is the reason to commission a survey.

How agricultural land quality is assessed

The Agricultural Land Classification grades land from 1 to 5 on the basis of physical limitations on agricultural use: climate, site factors such as gradient and flood risk, and soil properties including texture, depth, stoniness, wetness and droughtiness. Grade 3 is subdivided into 3a and 3b, and that subdivision is the one that matters, because 3a is within the best and most versatile category and 3b is not.

The published provisional ALC mapping was produced at a scale intended for strategic planning, typically covering large areas with a single grade and without the 3a and 3b split. It is useful for a first look and not usable as evidence. Overlay the site on the provisional mapping to understand the risk, then commission a detailed survey.

A detailed survey involves auger borings and soil pits on a grid across the site, field description of each horizon, and laboratory analysis where texture or stoniness is borderline. The method follows the revised guidelines and criteria published for grading agricultural land, and the work is done by a soil scientist rather than by an ecologist or a planner.

Why grade matters to the policy test

Where a site is mostly 3b, 4 or 5, the agricultural land argument is weak and the case turns on landscape and visual effects instead. Where it is substantially 1, 2 or 3a, the authority has to weigh the loss, and objectors will press the point.

Two arguments carry weight in response. The first is that the land is not lost: panels are mounted on piles, the ground between and beneath them remains in agricultural use as grassland, and sheep grazing continues through the operational life. That argument is stronger where the design supports it, with generous row spacing, no concrete bases, and stock-proof fencing that allows grazing.

The second is reversibility. A scheme with a defined operational period and a decommissioning scheme leaves the soil resource intact, which is a different proposition from building houses on the same field.

What does not help is an assertion that the land is poor quality without a survey to prove it. Councils have seen that too often.

The survey needed and its seasonal limits

Field survey for ALC can be carried out through most of the year, with one real constraint: soil cannot be properly described when it is waterlogged or frozen, and wetness class assessment is unreliable in extreme conditions at either end. Allow for weather delay rather than programming the survey for January and hoping.

Sampling density is the variable that gets squeezed. A density too low to support the 3a and 3b split invites a challenge from the authority's own adviser, and the whole report then carries little weight. Agree the grid spacing with the surveyor by reference to site size and variability, and show the boring locations on a plan in the report.

An Agricultural Land Classification report should present the grade map, the boring log, the classification reasoning for each grade boundary, and the proportion of the site in each grade as a figure in hectares. Councils usually expect that work to be signed by a suitably qualified soil scientist, and professional review is strongly advised before it goes in.

Landscape and visual evidence expected

Solar farms are low, extensive and reflective, and a landscape objection turns on extent and field pattern rather than height. The usual evidence is a Landscape and Visual Impact Assessment prepared to the third edition of the Guidelines for Landscape and Visual Impact Assessment, with a zone of theoretical visibility, agreed viewpoints and photomontages from them.

Four points recur in officer reports:

• Visibility from public rights of way crossing or adjoining the site, which is usually more important than visibility from roads.
• The effect on field pattern where hedgerows would be removed for access or cable routes.
• Cumulative effect with other consented or operational schemes in the same landscape character area.
• The adequacy of proposed screening in its first five years rather than at maturity.

That last one is where applications lose. A new hedge drawn at mature height on a photomontage is not mitigation for year one, and a condition requiring planting in the first available season does not change the physics.

Glint, glare and aviation safeguarding

Where a site lies near a licensed aerodrome, a gliding site or a military airfield, a glint and glare assessment is normally required, modelling reflections towards runway approaches, control towers and flight paths. The assessment also looks at nearby dwellings and roads, though the aviation receptors are the ones that produce objections from safeguarding consultees.

Mitigation is usually about panel orientation, tilt angle and screening, and occasionally about excluding part of a site. Raise it early with the aerodrome operator, because a safeguarding objection arriving in week ten of a determination is difficult to resolve inside the period.

Grid connection and cable route consents

The grid connection is frequently the part that defeats a scheme, and it is the part least often resolved at application stage. A connection offer sets the point of connection, the capacity and the date, and the route between the site and that point may cross land in other ownership.

Three separate consent questions arise. Whether the cable route needs planning permission or falls within the permitted development rights available to electricity undertakers. Whether a substation compound needs its own permission and where it sits visually. And whether highway works for a cable crossing need a street works agreement with the highway authority.

Describe the connection arrangement in the application even where it is consented separately. An officer who cannot see how the electricity leaves the site will ask, and the answer will take three weeks by email.

Decommissioning and the temporary permission

Most ground-mounted solar permissions are granted for a defined period, with a condition requiring removal of the equipment and restoration of the land within a stated time after generation ends. The period varies and is a matter for the authority, so propose one and justify it by reference to the design life of the equipment and the connection agreement.

A decommissioning and restoration scheme, secured by condition or obligation, should address removal of panels, frames, piles, cables and the substation, treatment of access tracks, reinstatement of soil profiles, and a timescale. Where soils are stripped at construction, the handling and storage method matters as much as the restoration specification, because compacted and mixed soil does not recover its original grade.

An illustrative example

A 30 hectare arable field is proposed for a ground-mounted scheme. The provisional mapping shows grade 3 across the whole field. A detailed survey with borings on a 100m grid finds 11 hectares of 3a on the drier southern slope and 19 hectares of 3b on heavier soils to the north. The layout is revised to concentrate panels on the 3b area, leaving a 3a margin in arable cropping, and the statement quantifies the best and most versatile land affected in hectares. This example is illustrative and the grading on any other site would differ.

The same logic about using the least constrained land first applies to other renewables on a holding, whether that is solar canopies over car parks or farm wind turbines within permitted development limits.

One honest uncertainty. Larger solar schemes can fall to be determined as nationally significant infrastructure under the Planning Act 2008 rather than by the local planning authority, and the generating capacity threshold for solar has been changed, so check the current figure before assuming the route.

This is general guidance, not legal advice. Agricultural land classification and landscape assessment are specialist disciplines, so take advice from qualified professionals and check the position with your local planning authority.

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