Peak Shaving & Load Shifting: Battery storage for business

Why peak shaving is the core money-saving case for battery storage for business

For most UK businesses the bill is no longer mostly about the units of electricity you use. Non-commodity charges, the red-band Distribution Use of System charges, capacity-market levies and residual charges, now make up a large and rising share of what you pay, and they are concentrated into predictable expensive windows. The red DUoS band, typically weekday late afternoon into early evening, costs far more per kWh than the green or amber bands, and capacity-based standing charges are driven by your peak demand. A battery that discharges across those red half-hours and your demand spikes cuts both the unit charges and the capacity charges at once, while charging back up overnight on a cheap tariff or from surplus solar. This is the most controllable saving in commercial energy, because unlike wholesale prices the charging structure is published in advance and you can design straight to it.

Peak shaving is the strongest fit for battery storage for business where demand is spiky and predictable, process plant with heavy machinery, refrigeration that cycles hard, EV charging hubs that pull short severe spikes. The old Triad regime, the three winter half-hours that once set transmission charges, has been replaced by fixed banded residual charges, so the classic Triad-avoidance play no longer exists in its old form. Many competitors still talk about it, which is exactly why accurate DUoS-band and capacity-charge modelling now wins. We model the current charging structure, not yesterday's, and we shave the peaks that actually cost you money today.

The reason this matters more every year is that the expensive part of the bill keeps moving away from the commodity. Wholesale prices remain elevated and volatile, but it is the non-commodity charges, the red-band DUoS, the capacity-market levy, the residual charges, that are hard to forecast and rising as a share of the total. A peak-shaving battery is the most direct lever a business has against that structure, because it acts precisely in the half-hours where the charges concentrate. It is also a lever you control: you are not betting on a market price, you are cutting a charge that is published in advance. That is why a peak-shaving case stands on its own even when wholesale arbitrage and grid-services income are stripped out, and why we build the model that way, with everything else treated as upside on top of a saving you own.

What a typical install looks like and how we size it

A peak-shaving battery typically lands in the 100 kW / 200 kWh to 1 MW / 2 MWh range, sized by two separate numbers that are easy to confuse. Power, in kW, is set by the size of the demand peak you need to flatten. Energy, in kWh, is set by how long that peak lasts. Most behind-the-meter commercial systems settle at 1.5 to 2.5 hours of duration, for example 250 kW backed by 500 kWh, which is enough to ride across a red-band window or a process spike without running flat. Because the battery shifts rather than generates power, the carbon saving varies with how much of your peak import you displace and how dirty the grid is in your peak window. We never quote a size from a rule of thumb. We pull at least twelve months of half-hourly data, overlay your DUoS band schedule, identify the red-band half-hours and the capacity-chargeable window, and size power and duration to the peaks that carry the cost.

The detail matters because the value lives in the tail of your demand curve. A site with occasional very sharp spikes wants high power and modest duration. A site with a long sustained afternoon plateau wants more energy. Getting that power-to-energy ratio right is the difference between a battery that clips every expensive peak and one that runs out halfway through. We model both against your data and show you the avoided charges half-hour by half-hour.

Chemistry and degradation feed straight into the sizing decision. We specify lithium-iron-phosphate cells for almost all commercial peak-shaving installs because they combine long cycle life with strong thermal stability, and a peak-shaving battery cycles hard every working day, so cycle life is not academic. Quality lithium-iron-phosphate cells are typically warranted for around 6,000 to 10,000 cycles, or ten years, to roughly 70 percent retained capacity, and we size so the system still meets your peak-shaving target near the end of that life rather than only at the start. Where the duty is heavy, planned augmentation keeps the usable energy on target. We state the warranted throughput and degradation curve in the proposal, so the saving you are shown in year one is one the asset can still deliver in year eight or nine.

Costs, payback and tax relief

A peak-shaving project typically runs £120,000 to £1.4m depending on power, duration and any switchgear, with a simple payback near 6.5 years in 2026 and faster where your red-band exposure and capacity charges are high. Qualifying battery plant is plant and machinery, so the Annual Investment Allowance covers the first one million pounds at 100 percent and the 50 percent First-Year Allowance applies above that, since storage is a special-rate asset, which for a limited company can return up to around a quarter of the project value as tax saved in year one. Where the site also has solar, the Smart Export Guarantee lets the battery time any export into higher-priced windows. The core return, though, is demand-charge avoidance you control, not export income, and our cost guide models it from your own DUoS bands.

Funding routes in detail

Capital is rarely the blocker. The plant and machinery capital allowances are the primary route, 100 percent Annual Investment Allowance on the first one million pounds of qualifying spend, then a 50 percent First-Year Allowance on the balance, which is worth confirming with your accountant for your accounting period. Where the building qualifies as residential or relevant-charitable, the 0 percent VAT relief on standalone retrofit storage can apply through to 31 March 2027 before moving to 5 percent, though general commercial premises such as a standard factory or warehouse do not qualify. For larger sites, NESO grid services, Dynamic Containment, the Balancing Mechanism and the Capacity Market, can add income, with revenue stacking across Dynamic Containment and the Balancing Mechanism now permitted, but frequency-response prices have become volatile and saturated, so we model that strictly as upside and build the case on demand-charge savings. The Industrial Energy Transformation Fund can support storage where it forms part of a wider qualifying decarbonisation project at an industrial site, not as a standalone battery. We compare capital, asset finance, lease and shared-savings routes side by side.

Compliance and sector considerations

A peak-shaving battery needs a G99 connection agreement, and where you intend to participate in demand-side response, additional metering may be required. If the battery is sited near a hazardous zone, DSEAR and ATEX considerations apply. The battery room or enclosure needs fire separation in line with PAS 63100 principles and your insurer's requirements, and the system should meet BS EN 62933 for system safety with cells to BS EN 62619. Spiky industrial sites in particular benefit from early insurer engagement, because correctly specified lithium-iron-phosphate systems with battery management, thermal monitoring and fire detection are exactly what insurers want to see. Behind-the-meter enclosures on an existing site are often permitted development or a minor application, subject to size, siting and any conservation constraints.

How we approach this kind of project

We start with twelve months of half-hourly meter data and your current DUoS band schedule, because peak shaving is a data exercise before it is an engineering one. We model the red-band half-hours, the capacity-chargeable window and the demand spikes, and we size power and energy to the peaks that carry real charges. We design for self-consumption and demand-charge avoidance as the core case and treat any grid-services or export income as upside only, so the model does not lean on revenue that has proven fragile. We check enclosure siting, fire separation and any DSEAR exposure early, and we submit the G99 application alongside the survey so the network clock starts immediately. You receive a fixed-price proposal stating the warranted throughput and degradation curve, an insurance-backed warranty, and the full spreadsheet so your finance team can test every assumption.

A behind-the-meter peak-shaving project typically runs four to nine months from contract to commissioning, with one to six weeks of physical installation once on site, and the network connection is almost always the longest item, which is why the G99 application goes in early. After commissioning, the real performance comes from the control logic: a planned operation and maintenance contract provides remote monitoring with automated alerts, periodic inspection, firmware updates and battery-management oversight, and software-led optimisation decides when to charge and discharge against your tariff and DUoS bands. That optimisation is what keeps the battery clipping the right half-hours as the charging structure and your demand evolve, rather than running a fixed schedule that drifts out of date. Most clients pair the system with a ten-year-plus maintenance agreement aligned to the cell warranty so the demand-charge saving holds up across the asset's life.

An illustrative example

As an illustrative composite based on typical UK projects, and not a real named client: a precision-engineering plant ran a sharp weekday late-afternoon demand peak that overlapped the red DUoS band, on a single-shift-plus profile with an existing rooftop solar array spilling midday surplus. We modelled a 250 kW / 500 kWh lithium-iron-phosphate battery. In the model the red-band import on peak days fell by the large majority, capacity charges eased, and lifted solar self-consumption added to the saving, with the whole case built from half-hourly data and handed to the finance director to stress-test. The figures are illustrative and depend on your demand profile, DUoS bands and tariff.

Peak shaving is rarely the only job a battery does on a site, and that is part of its appeal: the same asset that clips your red-band demand can also store solar surplus, support a constrained connection, or back up a critical load, so the demand-charge saving is the foundation rather than the whole return. If your peaks come from EV chargers or a constrained connection, see EV charging hub storage and grid connection enabler storage, and if you already run solar, solar-plus-storage stacks naturally on top. When you are ready, read the cost guide and funding routes, request a free feasibility, or browse the battery storage FAQs.