Evidence base for a battery energy storage site

A grid-scale battery storage evidence base is shaped by two issues that do not arise on most rural applications: how the fire and rescue service will respond to a thermal event, and the fact that the inverters and cooling plant run continuously rather than during working hours. Get those two right and the rest of the application is an ordinary countryside scheme with a landscape, ecology and access case. Get them wrong and the objections write themselves.

Where battery storage sits in the planning system

Standalone electricity storage other than pumped hydro was taken out of the national infrastructure consenting regime in England in 2020, so battery storage schemes are determined by the local planning authority under the Town and Country Planning Act 1990 whatever their capacity. A 500 megawatt site and a 20 megawatt site go to the same committee.

That has consequences. Authorities vary widely in how much technical support they have available, the determination period is the standard major period rather than an infrastructure timetable, and the evidence base has to be written for a planning officer rather than an inspector with a technical remit.

Screening under the Environmental Impact Assessment Regulations 2017 is the first question on a larger site, particularly where the site area or the sensitivity of the location brings it within Schedule 2. Screen early, because the answer changes the survey programme.

Fire safety and the emergency services response

This is the issue that dominates consultation and it is worth addressing before the first objection arrives.

National planning guidance on renewable and low carbon energy encourages applicants to engage with the local fire and rescue service on battery storage proposals, and the fire service's response is what officers and members read most carefully. Engage at pre-application, in writing, and ask what the service wants to see.

The matters that come up consistently are access for appliances to every part of the site including the far side of the compound, the availability and volume of water for firefighting and where it comes from, separation distances between battery units and between the compound and any dwelling or combustible boundary, containment of contaminated firewater so it does not reach a watercourse or a groundwater source protection zone, gas and smoke dispersion in the event of thermal runaway, and remote monitoring with an agreed escalation and shutdown procedure.

A safety management plan covering those matters, prepared by someone with the relevant fire-engineering competence and agreed with the fire and rescue service, is normally secured by condition. That document is a fire-engineering deliverable rather than a planning statement, and it is not one of PlanScope's report types. Where the scheme includes a building that is a relevant building for Planning Gateway One, a Fire Statement is a separate statutory requirement, and it too needs a competent fire engineer.

Noise from inverters and cooling plant

Battery sites make a steady, often tonal, sound from transformers, inverters and air-cooled heat rejection plant, and it continues through the night. That combination, continuous operation with a tonal character, is what makes the noise case harder than it looks.

A Noise Impact Assessment to BS 4142 is the standard requirement. The elements that matter are a background sound survey at the nearest noise-sensitive receptors covering night-time periods, manufacturer sound power data for the actual plant proposed rather than a generic figure, a propagation calculation to each receptor, and the character corrections the standard requires for tonality and impulsivity.

Two practical points. Plant selection is part of the mitigation, so an assessment carried out before the equipment is chosen has to be redone or conditioned tightly. And cooling plant runs hardest on hot nights, when windows are open, which is the condition the assessment should test rather than an annual average.

Expect a condition fixing a rating level at the nearest receptors and requiring a post-commissioning verification survey.

Landscape effects and screening

Battery compounds are low but extensive, and they bring fencing, lighting columns, CCTV, hardstanding and a control building. The visual issue is usually the industrial character of the enclosure rather than its height.

A Landscape and Visual Impact Assessment following the recognised guidance, with viewpoints agreed with the authority, is the normal requirement outside urban areas. Screening planting takes years to work, so present the effects at year one as well as at maturity and say which case you are asking the authority to accept.

Lighting deserves its own layout with spill contours. A compound lit for security in open countryside changes the character of a wide area, and a scheme lit only on activation by detection is a much easier case to argue.

Ecology and biodiversity net gain

Many battery sites sit on improved or semi-improved grassland, which produces two effects worth planning for.

The baseline survey is usually straightforward, though a preliminary ecological appraisal still has to check for protected species along boundaries, in ditches and in any farm structures. Where reptiles, badgers or nesting birds are present, seasonal survey windows apply, and a licensed ecologist is legally required for protected species work under the habitats and wildlife legislation.

Biodiversity net gain is the more interesting part. Because the compound retains open ground between the units and around them, a battery site can often deliver its ten per cent on site through grassland enhancement and boundary planting, which avoids buying units off site. A Biodiversity Net Gain Assessment using the statutory metric has to be completed by a competent person under the Environment Act 2021 regime, and the biodiversity gain plan is approved by the authority after permission, so the thirty-year management and monitoring commitment needs to be priced into the scheme.

Where the site is greenfield agricultural land, an agricultural land classification survey may be needed to establish whether it is best and most versatile, because loss of that land is a policy consideration in its own right.

Access, abnormal loads and construction traffic

Transformers and containers arrive on vehicles that most rural accesses cannot take. Work the route backwards from the nearest strategic road, identify the pinch points, and agree the route with the highway authority before the application.

A Construction Traffic Management Plan is normally conditioned, and for abnormal indivisible loads the plan needs to cover the escorting arrangements, any temporary works such as verge protection or sign removal, and the hours of movement. Operational traffic is trivial by comparison, a few maintenance visits, which is worth stating plainly because objectors assume otherwise.

Grid connection and the red line question

The connection is where applications get procedurally untidy. Decide early what sits inside the application boundary: the compound only, or the compound plus the cable route and the substation works.

Cabling and works by a licensed electricity undertaker have their own permitted development rights under the General Permitted Development Order, which is why cable routes are often outside the red line. That is legitimate, and it has to be explained rather than left implicit, because an objector will argue that the scheme has been artificially split. State in the planning statement what is being consented where and under what power.

Where the connection point is far from the site, the cable route may cross land you do not control, and the environmental effects of that route are a matter the authority may want covered even if the works themselves are permitted.

Decommissioning and restoration

Battery permissions are usually temporary, for a period tied to the asset life, with a requirement to decommission and restore the land.

Set out the proposed period, the decommissioning method, what is removed and to what depth, how the land is restored and to what use, and the mechanism securing it. Authorities increasingly want financial security through a planning obligation rather than a condition, because a condition against a company that no longer exists is worth little. Expect to negotiate the form and the amount.

Enter your postcode on PlanScope to see which reports your site is likely to need. The 12 flat brownfield report list shows the same exercise on an urban residential scheme. 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 rather than legal advice, so check the position with your local planning authority or a qualified professional before relying on it.