Battery storage alongside a solar scheme

A battery storage planning application sits with the local planning authority whatever the capacity, because electricity storage was taken out of the nationally significant infrastructure regime in England and Wales and left with councils. Co-locating storage with a solar farm changes the application in four places: fire safety, noise from inverters and cooling plant, the layout required to fight a fire in a container yard, and the decommissioning position for equipment with a shorter life than the panels around it.

The planning principle is usually the easy part. The detail is where these schemes stall.

How storage is treated in planning terms

A battery energy storage system has no use class. It is assessed as a sui generis use or, where it is ancillary to the generating station, as part of that development. Most authorities prefer a single application covering generation and storage together with a description that names both, because a storage element described loosely as ancillary plant invites an argument later about what was permitted.

Capacity does not change the decision maker. Storage facilities other than pumped hydro were removed from the Planning Act 2008 regime, so a large battery yard is a local application even where a solar array of comparable output would not be. Thresholds for solar generation have moved, so check the current figure rather than working from an older one.

Where the storage is bolted onto a consented solar scheme after the event, the route is usually a fresh full application rather than a variation, since the character of the development changes.

Fire safety and the evidence authorities expect

This is the issue that attracts objections, and the objections are often better informed than applicants expect.

The concern is thermal runaway in a lithium-ion cell propagating through a module and then a container, with flammable off-gassing before ignition. The planning response is a battery safety management plan covering the chemistry proposed, the detection and suppression designed in, separation distances between containers, the approach to off-gas venting, and what the fire and rescue service is expected to do if it attends.

Consult the fire and rescue service early and record the response in the submission. Authorities take a service that has engaged and is content far more seriously than an applicant's assurance that the technology is safe. Where the authority asks for a full fire engineering document, that is a report type where a professional with fire engineering competence is legally expected, and a drafted document is a starting point for that professional rather than a substitute.

Three site questions follow from the fire case and belong on the layout rather than in the text.

• An emergency water supply of stated capacity, whether a tank, a lagoon or a hydrant, with the draw point reachable by an appliance.
• Separation distances between containers and from the boundary, dimensioned on the plan.
• Containment for firewater run-off, so that what is used to fight a fire does not reach a watercourse.

Noise from inverters, transformers and cooling

Storage runs at night, and that is what distinguishes its noise case from a solar array's.

Inverters, transformers and the air conditioning serving the battery containers all produce sound with a tonal character, and transformer hum attracts an acoustic feature correction under BS 4142. The assessment compares the rating level at the nearest residential receptor with the measured background sound level, and rural night-time background levels are low. A site that passes comfortably in the afternoon can fail at 2am.

Design responses in rough order of usefulness: set the plant back from the boundary, orientate cooling units away from receptors, specify quieter units at procurement rather than assuming attenuation later, use acoustic barriers close to the source, and only then consider operational restrictions, which operators resist because the market they serve runs overnight. A Noise Impact Assessment with a night-time baseline survey is the document that settles it, and taking the baseline in a quiet season matters as much as the equipment data.

Layout, landscape and the land underneath

Containers are tall, rectangular and industrial in a way that panels are not. A solar array reads as a low horizontal field. A battery yard reads as a small industrial compound, and the landscape argument has to be made separately for it.

A Landscape and Visual Impact Assessment prepared to the third edition of the landscape institute guidelines covers the receptors and viewpoints agreed with the officer. Put the compound in the least exposed part of the site, use existing landform rather than relying on new planting that takes 15 years to perform, and show the compound in the photomontages rather than only the panels.

Agricultural land quality is the other site-level question. Where the proposal takes best and most versatile land, national policy expects poorer quality land to be used in preference, and the evidence is an Agricultural Land Classification survey carried out by a soil scientist on ground that is not waterlogged. Survey timing is a programme risk worth planning for.

Biodiversity net gain applies, and a compound of hardstanding and gravel delivers none of it, so the gain has to come from the land around the development. A Biodiversity Net Gain Assessment using the statutory metric has to be completed by a competent person under the Environment Act 2021 regime, with the biodiversity gain plan approved by the authority before development begins.

Decommissioning, restoration and the life of the equipment

Batteries have a shorter working life than panels, and cells get replaced during the permission. Say so, because an authority that believes the containers are permanent will condition them as permanent.

Useful decommissioning conditions cover three things. A trigger, usually a stated period after the equipment ceases to export or store electricity. A scope, listing what is removed and to what depth foundations are grubbed out. And a restoration specification with an aftercare period, which on agricultural land means soil handling that leaves the field usable.

A financial guarantee is sometimes requested. Whether an authority can require one depends on the obligation tests, and the arguments usually land in a section 106 rather than a condition. Expect the question on a large scheme.

The submission in practice

The core application documents still apply, and the technical set usually adds the battery safety management plan, the noise assessment with a night-time baseline, the landscape and visual work, ecology and biodiversity net gain, agricultural land classification where relevant, a construction traffic plan for abnormal loads, and drainage covering both the compound and the firewater containment.

Grid connection is a commercial matter rather than a planning requirement, and an authority cannot refuse for want of a connection offer. It will come up at committee anyway, so having a position on deliverability saves time. The same applies to the question of what happens to the cells at end of life, which is where our note on solar canopies over car parks and the wider site reuse question meets the same objection.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

Browse the 66 report types to see which documents a co-located storage and generation scheme is likely to need.

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