Grid Connection Enabler (Behind-the-Meter): Solar battery grants

Using a battery to beat a constrained grid connection, and funding it

One of the most valuable but least understood uses of commercial battery storage is as the route around a constrained grid connection. Grid connection and capacity upgrades face long DNO queues, and that queue is often the single thing blocking a business from adding EV charging, heat pumps, or new production load. If your DNO has quoted a six-figure reinforcement and a long wait to lift your import capacity, a behind-the-meter battery with a G100 import limitation scheme can let you add that load while staying inside your existing agreed capacity. The battery buffers the peak import so the site never breaches its limit, which avoids or defers the reinforcement cost and the connection queue entirely. For a business looking at the funding side, this configuration is unusual in that the headline benefit is often avoided capital expenditure rather than an ongoing energy saving, and that avoided capex is frequently larger than the battery itself.

This page exists because the grid-constraint angle is poorly explained across the market, and getting it right is a genuine technical-credibility opportunity. Often the battery is the solution to the constraint rather than a victim of it: instead of the connection blocking the battery, the battery unblocks the expansion. The funding case here is the same set of capital allowances that apply to every other battery configuration, but the value being unlocked is different. Instead of cutting your bill, the battery lets a project proceed that would otherwise be blocked or delayed by 18 months or more, since G99 study and connection timescales can run anywhere from 3 to 18 months depending on network capacity. Where that project is itself revenue-generating or strategically necessary, the battery becomes the enabling asset for the whole investment, and the allowance position on the battery sits alongside the wider capital case for the expansion it makes possible.

It helps to be precise about what a constrained connection actually means in practice, because the constraint is what the funding has to overcome. Your site has a Maximum Import Capacity agreed with the DNO, and adding EV chargers, heat pumps or production plant can push the instantaneous peak above that figure even where the average load is comfortable. The conventional answer is a reinforcement, where the DNO upgrades the network to lift your capacity, but that carries a six-figure cost and a place in a queue that can stretch well over a year on a busy network. A behind-the-meter battery sidesteps both by absorbing the peaks that would breach the limit, so the agreed capacity never has to change. That is why the funding conversation here is so often about avoided capital rather than energy savings: the most valuable thing the battery does is make a reinforcement unnecessary.

What a typical install looks like and how we size it

A grid-connection-enabler battery usually lands between 250 kW / 500 kWh and 2 MW / 4 MWh, sized by the gap between your existing agreed capacity and the new peak demand you want to add. The sizing logic is different from peak shaving: here we model the import profile of the new load, EV chargers, heat pumps or production plant, against your existing Maximum Import Capacity, and size the battery to buffer the difference for as long as the peak lasts. The G100 scheme reduces import to keep the site within its agreed limit, typically reacting within 15 seconds and within 60 seconds at most, so the battery must have the power to respond quickly and the energy to hold through the peak. DNO consultation is essential before final sizing, because the agreed capacity and the network's appetite for the limitation scheme shape the design, and the right size on paper is worthless if the DNO will not accept the scheme. As with all storage, the CO2 saving varies with how the battery is charged. We pull at least 12 months of half-hourly data and the proposed new-load profile before sizing, because the whole point of this configuration is the headroom it creates against a fixed limit, and that can only be sized from the real numbers.

Costs, payback and tax relief

A grid-connection-enabler project typically falls between £300,000 and £2.6m, with a simple payback near 7.5 years on the energy savings alone, though the real return is usually sharper once the avoided reinforcement capex and the deferred connection queue are counted. 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. Because the battery enables an investment rather than simply saving on the existing bill, we model the full picture: the allowance on the battery, the avoided DNO reinforcement cost, the deferred queue, and any energy savings from off-peak charging and demand shaving. For many businesses the deciding factor is not the simple payback at all but the fact that the expansion can happen now rather than in 18 months, and the cost of the wait is what the battery removes. Our cost guide sets out how the avoided-capex and energy-saving streams combine.

Funding routes in detail

The funding routes for this configuration are the same reliefs that apply across commercial storage, with the avoided reinforcement as the standout. 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 the G100 control infrastructure as special-rate assets. Where the new load is solar-charged, the Smart Export Guarantee applies to any surplus the site still exports. For larger assets that also provide frequency response, NESO grid services can add income, with revenue stacking across Dynamic Containment and the Balancing Mechanism now permitted, but we treat that as upside given how volatile and saturated frequency-response prices have become. Where the enabling project is part of a wider industrial decarbonisation package in an eligible SIC code, the Industrial Energy Transformation Fund may be relevant at a 30 to 50 per cent intervention rate, subject to the current DESNZ competition window, since it funds qualifying decarbonisation packages rather than standalone batteries. The strongest part of the funding story here, though, is not a relief at all: it is the reinforcement cost you never have to spend and the queue you never have to join. We model capital, finance, lease and shared-savings routes side by side.

Compliance and sector considerations

This configuration needs a G99 connection agreement for the storage asset and a G100 export and import limitation scheme to hold the site within its Maximum Import and Export Capacity, typically reacting within 15 seconds and within 60 seconds at most. DNO consultation before final sizing is not optional, because the whole approach depends on the network accepting the limitation scheme as an alternative to reinforcement, and we confirm that route with your DNO before final design. Across the site level, the wider standards 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, BS 7671 for the installation, and CDM 2015 where the work exceeds 30 person-days. Behind-the-meter enclosures on existing commercial sites are often permitted development or a minor application, subject to size and siting, with separation distances, firefighting access and noise to consider. The G100 scheme and the DNO agreement are the long poles, which is exactly why we start them on day one rather than after the survey.

How we approach this kind of project

We open the DNO consultation and submit the G99 application alongside the survey, because on this configuration the network conversation is the entire premise, and starting it late kills the timeline advantage that justifies the battery in the first place. We model the new-load import profile against your existing agreed capacity from half-hourly data, size the battery to buffer the gap, and design the G100 scheme to hold the site within its limit while reacting fast enough to satisfy the DNO. We carry out roof, plant-room and asbestos checks before we quote a fixed price. You receive a fixed-price proposal with the warranted cycle count, throughput and degradation curve stated and a 10-year insurance-backed workmanship warranty, and we share the full model, including the avoided-reinforcement comparison, so your finance team can stress-test the whole case rather than just the battery in isolation. If a straightforward reinforcement turns out cheaper and quicker than the battery for your specific situation, we will say so.

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, holding the site within its agreed import capacity and buffering the charger spikes. 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 13 months saved. The figures are illustrative and depend on your connection, DNO terms and the new load you are adding.

If the new load you want to add is EV charging specifically, see EV charging hub storage, and if your priority is trimming demand charges on the existing load, see peak shaving and load shifting. 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.