Solar battery grants: the funding, reliefs and export income behind solar-plus-storage
Solar battery grants are the first thing most businesses ask about when they look at adding storage to their solar, and we would rather be honest about them than imply a cheque exists that does not. There is no single headline cash grant for commercial battery storage in the UK. What there is instead is a stack of reliefs and income streams that, taken together, materially change the after-tax cost of a solar-plus-storage system: plant and machinery capital allowances, the Smart Export Guarantee on whatever you still export, a narrow 0 per cent VAT relief for residential and charity-occupied buildings, NESO grid-services income for larger assets, and the Industrial Energy Transformation Fund where storage forms part of a wider decarbonisation project. This page sets out which of those apply to you, how they stack, and how we size and deliver a battery so the funded benefit is as large as it honestly can be.
The funding landscape: which schemes apply and how they combine
The largest lever for a limited company is the Plant and Machinery Capital Allowances. Battery storage and its associated infrastructure qualify as plant and machinery, so the Annual Investment Allowance covers the first £1m of qualifying spend at 100 per cent. It is worth being precise, because the market routinely overstates this: solar and storage are special-rate assets, so the 100 per cent full-expensing regime does not apply to them. Above the £1m AIA cap a 50 per cent first-year allowance applies to the balance. For a limited company that can be worth up to around a 25 per cent effective tax saving in year one, depending on how your spend sits against the cap, and your accountant should confirm the position for the relevant accounting period.
The Smart Export Guarantee pays for power you export, typically 4 to 15p per kWh and supplier-set, on MCS-certified installations up to 5 MW. A battery adds most of its SEG value not by exporting more but by shifting export into higher-priced windows on a time-of-use export tariff rather than spilling at midday for the lowest rate. The two reliefs combine cleanly: the capital allowance reduces the cost of the asset, and the export income tops up the everyday return alongside the self-consumption saving. For the narrow case of residential accommodation or a building used solely for a relevant charitable purpose, 0 per cent VAT on Energy Saving Materials covers standalone retrofit storage connected to the grid since 1 February 2024, runs to 31 March 2027, and is then set to move to 5 per cent rather than back to 20. General commercial premises do not qualify, a point routinely mis-stated, so we will tell you plainly if your building falls outside it. Larger behind-the-meter and grid-scale assets can also earn from NESO grid services (Dynamic Containment, Moderation and Regulation, the Balancing Mechanism and the Capacity Market), with revenue stacking across Dynamic Containment and the Balancing Mechanism now permitted, but frequency-response prices have become volatile and saturated, so we treat that as upside, never the foundation. Where storage sits inside a wider qualifying decarbonisation project on an eligible industrial site, the Industrial Energy Transformation Fund offers capital grants at a 30 to 50 per cent intervention rate, typically £100,000 to £30m per project, subject to the current DESNZ competition window. Our grants and funding guide works through each scheme in turn.
How we size solar-plus-storage to maximise the funded benefit
The reliefs only pay off on capacity that actually does work, so sizing is where the funding case is won or lost. Commercial battery sizing is driven by the demand profile and the value stack, never by headline kW: we size power (kW) to the peak you need to shave and energy (kWh) to the duration of that peak. Most behind-the-meter commercial systems land at 1.5 to 2.5 hours of duration, for example 250 kW / 500 kWh. For solar-plus-storage specifically, we size the battery to the daytime export surplus, not the PV array, because a large array on a daytime-busy site may have little surplus to store. A self-consumption battery typically lands between 50 kW / 100 kWh and 500 kW / 1,000 kWh and lifts self-consumption from a typical 40 to 60 per cent toward 80 per cent and above, saving in the region of 10 to 120 tonnes of CO2 a year depending on how much surplus it captures. We pull at least 12 months of half-hourly meter data and the site's current DUoS band schedule before final sizing, and confirm DNO import and export capacity early, because G99/G100 is usually the long pole. Oversizing wastes the funding, since unused capacity earns nothing while still attracting cost, which is exactly why we never quote a size from a rule of thumb before we have seen the data.
Costs and payback after the relief (illustrative)
As a 2026 rule of thumb, fully installed behind-the-meter storage lands at roughly £400 to £700 per kWh of usable capacity, falling toward £250 to £400 per kWh at multi-MWh scale. A solar-plus-storage project on this site typically falls between £60,000 and £600,000, with a simple payback near 7 years for a well-matched system and faster where the solar surplus and the import-to-export price spread are large. The capital allowance position improves the after-tax cost in year one, and the Smart Export Guarantee tops up the everyday return, so the funded payback is shorter than the headline figure suggests. These ranges are illustrative and depend entirely on your demand profile, tariff and how the spend sits against the £1m AIA cap, which is why we build every number from your real data and share the full model. Our cost and payback guide works through the allowance and export income on a self-consumption battery.
Compliance: the standards that make a system eligible and safe
MCS certification on the storage element matters for funding as well as quality, because the Smart Export Guarantee requires an MCS-certified installation. Alongside that we work to NICEIC or NAPIT electrical registration, BS EN 62619 for cell safety, BS EN/IEC 62933 for system safety, and PAS 63100:2024 fire-protection principles, with RECC and TrustMark where a residential or charitable supply is involved. A G99 connection agreement is required for storage above 16 A per phase (about 3.68 kW single-phase), which covers most commercial systems, while G98 covers small-scale connections. A G100 export and import limitation scheme holds a site within its agreed capacity, typically reacting within 15 seconds (60 seconds at most), and is often the route that lets a project proceed on a constrained network. Behind-the-meter enclosures on an existing commercial site are often permitted development or a minor application; we confirm the planning, separation and firefighting-access route in the feasibility study. The fire and insurance scrutiny on lithium-ion storage has tightened, which is why we specify thermally stable lithium-iron-phosphate cells and engage your insurer up front: the risk lies in cheap, non-compliant kit, which we do not install.
How we approach the application and the project
We start from your half-hourly meter data and your solar generation profile, size for self-consumption first, and model capital, asset finance, lease and shared-savings routes side by side so the funding fits your balance sheet rather than forcing a capital outlay. We confirm which reliefs your building and company actually qualify for before we quote, rather than implying a grant that does not apply. We submit the G99 application and open the DNO conversation on day one, because the connection timeline is usually the longest item. You receive a fixed-price proposal with the warranted cycle count, throughput and degradation curve stated, backed by a 10-year insurance-backed workmanship warranty, and the full model is shared so your finance team can stress-test every assumption and feed it into your own capital appraisal. If your surplus is small and a battery is not justified, we will tell you so rather than sell you one.
An illustrative example
As an illustrative composite based on typical UK solar-plus-storage projects, and not a real named client or real project: a Midlands precision-engineering plant on a single-shift-plus profile had a sharp weekday late-afternoon demand peak and an existing 300 kW rooftop array exporting surplus at midday, with an annual electricity bill near £420,000. A 250 kW / 500 kWh lithium-iron-phosphate battery integrated with the existing PV lifted solar self-consumption from 52 per cent to 84 per cent and cut red-band import sharply, for an indicative annual saving near £71,000 and a payback close to 6.4 years. The model was built from 12 months of half-hourly data and handed to the finance director to stress-test, with any frequency-response income treated as unmodelled upside. The figures are illustrative and depend on the site, the scheme rules at the time, and your generation profile, tariff and demand shape.
If you want to dig into a particular configuration, see solar-plus-storage self-consumption or peak shaving and load shifting. When you are ready, read the cost and payback guide, review the grants and funding routes, request a feasibility from your meter data, or work through the battery storage FAQs first.
