EV Charging Hub Storage: Solar battery grants

EV charging hub storage: funding the battery that makes more chargers possible

Rapid and ultra-rapid EV chargers create short, severe demand spikes that can trigger an expensive grid upgrade long before the average load justifies it. A single bank of ultra-rapid chargers all drawing at once can momentarily exceed a connection that copes easily with the site's normal load, and the DNO sizes the connection for that worst case. A battery buffers those spikes, charging off-peak and from on-site solar and discharging into the charging peaks, which lets you install more chargers on your existing connection and deploy far faster than DNO reinforcement allows. For an operator weighing the funding, this is often the cheapest enabler of a charging hub: rather than pay for a connection upgrade you cannot get quickly, the battery lets the existing connection do more. The capital allowance position applies to the battery in the usual way, and where chargers are grant-funded under the OZEV scheme that funding sits alongside the battery investment, though the schemes cover different parts of the project.

This page is for fleet depots, retail forecourts and destination charging sites that want to scale up charging without waiting on the grid. The funding story combines the capital allowances on the battery, the avoided or deferred reinforcement cost, the off-peak and solar charging savings, and, where applicable, the OZEV grant support on the charging infrastructure itself. It is one of the few configurations on this site where a charging-specific grant genuinely enters the picture, even though it funds the chargers rather than the battery. The key idea is that storage and charging are designed as one system: the battery is not a bolt-on, it is the thing that lets the connection carry a charging load it otherwise could not. We size the battery to the charger demand profile, model how it lets the connection carry more, and design the storage and charging infrastructure together so the two halves work as one.

The three site types each read the funding differently. A fleet depot charges predictably overnight on a cheap tariff, so the battery both buffers the depot charging peak and shaves the operational evening peak, and the case leans on demand-charge avoidance and the value of getting the fleet electrified now rather than after a reinforcement. A retail forecourt or destination charger sees revenue per charging session, so every additional charger the battery enables on the existing connection is direct income, and the funding case is driven by throughput as much as by saving. A mixed site does both. We tailor the model to which of these you are, because the same battery that looks like a cost-avoidance measure on a depot looks like a revenue-enabler on a forecourt, and the way the funding is best structured follows from that distinction.

What a typical install looks like and how we size it

An EV charging hub battery usually lands between 100 kW / 200 kWh and 1 MW / 2 MWh, sized to buffer the charger demand spikes that would otherwise breach the connection. The sizing logic starts from the charger profile: how many rapid or ultra-rapid units, their combined peak draw, and the realistic simultaneity, since chargers rarely all hit full power at the same instant. We model that against the site's existing agreed import capacity. The battery's power must cover the spike above the connection limit and its energy must hold through the charging peak, with off-peak and solar charging refilling it between peaks. Where solar is present, the daytime generation charges the battery and reduces grid draw further, which both lowers the running cost and stacks a self-consumption benefit on top of the enabling role. The CO2 saving varies with how the battery is charged, with the largest benefit where solar does the charging rather than the grid. We pull at least 12 months of half-hourly data plus the proposed charger schedule before sizing, because a battery sized to the wrong charger simultaneity either fails to enable the chargers, defeating the whole purpose, or carries unused capacity that earns nothing. Getting the simultaneity assumption right is the single most important judgement in the design.

Costs, payback and tax relief

An EV charging hub storage project typically falls between £120,000 and £1.4m, with a simple payback near 7 years on the energy savings, before counting the avoided reinforcement cost and the revenue the additional chargers generate, which is often the larger prize for a commercial charging operator. As special-rate plant, the battery draws 100 per cent Annual Investment Allowance on the first £1m of qualifying spend and a 50 per cent first-year allowance on the balance, which for a limited company can be worth up to around a quarter of the project value back as tax saved in year one, depending on how the spend sits against the £1m cap. The funding picture is strongest when you read it as a whole rather than as a battery payback in isolation: the allowance on the battery, the reinforcement you avoid, the off-peak and solar charging savings, and the throughput the extra chargers unlock combine into the real return. For a destination or forecourt operator, every charger that can be added on the existing connection is additional revenue that the battery makes possible. Our cost guide shows how these streams combine for a charging hub.

Funding routes in detail

The funding routes combine reliefs, avoided cost and, uniquely on this site, a charging-specific grant. The primary route is the Plant and Machinery Capital Allowances: 100 per cent AIA on the first £1m, then 50 per cent first-year allowance on the balance, applied to the battery and switchgear as special-rate assets. Where chargers are grant-funded, the OZEV scheme requirements apply to the charging infrastructure, which sits alongside but separate from the battery funding, so the grant supports the chargers while the allowances support the battery. The Smart Export Guarantee applies to any solar surplus the site exports rather than stores. For larger assets, NESO grid services can add income between charging peaks, treated as upside given how volatile and saturated frequency-response prices have become rather than as the foundation of the case. The avoided DNO reinforcement, while not a grant, is often the single largest line in the funding case, since it removes a six-figure cost and a long queue and lets the chargers go live in months rather than the better part of two years. We model capital, asset finance, lease and shared-savings routes side by side so the funding fits the way you want to finance the hub.

Compliance and sector considerations

An EV charging hub battery needs G99 for the storage and G100 for the combined site export and import limitation, so the chargers and battery together stay within the agreed capacity. The charger installation must meet BS 7671 and, where grant-funded, the OZEV scheme requirements. Fire separation between the battery enclosure and the charging bays must follow your insurer's and the NFCC's guidance, which matters more here than on most sites because the battery and the chargers share a compact area where vehicles and people are present. Across the site level the wider framework applies: BS EN 62619 for cell safety, BS EN 62933 for system safety, PAS 63100:2024 principles for fire protection, NICEIC or NAPIT electrical registration, and CDM 2015 where the work exceeds 30 person-days. Behind-the-meter enclosures on existing commercial sites are often permitted development, subject to size and siting, with separation distances, firefighting access and noise to consider, and we confirm the planning and separation route in the feasibility study so the layout is right before any groundwork.

How we approach this kind of project

We design the storage and the charging infrastructure together rather than bolting a battery onto a charger layout, because the whole point is that the two work as one system within the connection limit. We model the charger demand profile and simultaneity against your existing agreed capacity from half-hourly data, size the battery to buffer the spikes, and design the G100 scheme to hold the combined site within its limit. We submit the G99 application and engage the DNO on day one so the connection clock starts, carry out roof, plant-room and asbestos checks before we quote a fixed price, and deliver a fixed-price proposal with the warranted cycle count, throughput and degradation curve stated, backed by a 10-year insurance-backed workmanship warranty. The full model, including the avoided-reinforcement comparison and the throughput the extra chargers unlock, is shared so your finance team can stress-test the whole hub case rather than the battery alone.

An illustrative example

As an illustrative composite based on typical UK projects, and not a real named client or real project: a regional distribution depot wanted to electrify 40 vans and add 8 rapid chargers, but the DNO quoted a six-figure reinforcement and an 18-month wait to lift the import capacity, with the existing connection nearly maxed at peak. A 1 MW / 2 MWh lithium-iron-phosphate battery with a G100 import limitation scheme let the chargers and the van fleet deploy on the existing connection inside about 5 months instead of waiting 18 for reinforcement, buffering the charger spikes and shaving the depot's evening peak as well. The indicative position avoided roughly £180,000 of reinforcement capital plus around £40,000 a year in off-peak charging and demand-charge savings, for a payback near 7.2 years on the savings alone, before the value of the chargers going live more than a year sooner and the charging throughput that earlier deployment unlocked. The figures are illustrative and depend on your charger plan, the realistic simultaneity across the units, your connection and your DNO terms, which is exactly why the design starts from the half-hourly data rather than a headline charger count.

If the wider point is using a battery to get around a constrained connection for any new load, see battery storage as a grid connection enabler, and if you also have rooftop solar to pair with the chargers, see solar-plus-storage. When you are ready, read the cost and payback guide, review the funding routes, request a feasibility from your meter data, or work through the battery storage FAQs.