Peak Shaving & Demand Management for UK Commercial Sites

Why this use case matters for UK businesses

Peak-shaving only pays because distribution charges are banded by time of day: our DUoS charges guide explains the red band, capacity charges and how to find the hours that apply to your supply.

For most commercial sites, the expensive electricity is not the average unit it is the peak. A spiky daytime load drives up three separate charges at once. The red-band Distribution Use of System (DUoS) rate applies to every unit drawn across the late-afternoon peak. The available-capacity charge bills you on the agreed import capacity (kVA) you reserve, whether you use it or not. And the peak unit rate itself can sit anywhere between 25p and 45p/kWh on a half-hourly contract. Trim the height of your demand curve at the worst hours and all three charges fall together.

Peak shaving uses a behind-the-meter battery to do exactly that. The battery discharges during the costly window so the meter sees a lower, flatter draw, then recharges when power is cheap. Nothing about your production changes, the machines run as before. What changes is the shape of demand the grid sees, and that shape is what your bill is built on. Sizing starts with power and energy, and kW vs kWh explains how to read them. If you are weighing whether a battery suits the site at all, our buying guide to commercial batteries sets out six checks to run on your half-hourly data.

There is a second, often larger prize. A constrained site that is bumping against its agreed import capacity can use a battery to draw more power during peaks than the grid connection alone would allow, because the battery supplies the difference. That lets a business add EV chargers, new plant, or an extra shift without paying for a costly DNO reinforcement. Deferring or avoiding that upgrade frequently dwarfs the unit-rate savings. See our cost breakdown for how these streams combine.

How the battery does it

Everything starts with your half-hourly meter data. Any business on a maximum-demand or half-hourly settled supply has it, and it is the single most important input. Twelve months of half-hourly readings give a load profile that shows exactly when your demand peaks, how high it climbs, how predictable those peaks are, and how long they last.

A typical manufacturing or process site shows a recognisable signature: a sharp morning ramp as plant starts up, a sustained daytime plateau, and demand spikes when several large loads coincide. The expensive part is the weekday evening peak, broadly 16:00 to 19:00, when red-band DUoS and the highest unit rates land at the same time. The battery is programmed to discharge across that window, shaving the top off the demand curve so the grid never sees your true maximum.

The control system watches demand in real time and holds the metered draw below a target threshold, releasing stored energy whenever the site would otherwise breach it. Outside the peak, when power is cheapest overnight or in the small hours, it recharges ready for the next day. Because the peaks on a process site are usually predictable, the same pattern repeats day after day, which is what makes the saving bankable rather than speculative. Where the data shows the numbers do not stack up, that is the answer, and it is the point of working from real data rather than averages.

Sizing and economics

A storage system is sized on two numbers, not one. Power, measured in kW, is how hard it can push, it sets how much you can shave off an instantaneous peak. Energy, measured in kWh, is how long it can sustain that push. A 250 kW / 500 kWh system is a “2-hour” battery: it can hold 250 kW of shaving for two hours before it is empty. Get either dimension wrong and the saving disappears, too little power and you cannot flatten the spike, too little energy and the battery runs flat before the peak ends.

For peak shaving the indicative envelope is 200 to 1,000 kWh of energy and 100 to 500 kW of power, run at around 0.5C so the cells discharge over roughly two hours. Cost follows the published UK bands on the cost page for the size you need, and the annual saving depends entirely on the shape of your peaks, your charging bands and your capacity agreement, so this page gives no typical saving. The guide to kW vs kWh explains how to read the two numbers.

What moves the cost? Scale is the biggest lever: the published UK bands on the cost page show the cost per kWh falling as systems get larger. Then there is the electrical infrastructure: switchgear, the G99 connection works, civils and any DNO requirements. The economics improve sharply when several value streams stack, peak-rate avoidance, red-band DUoS, the kVA charge reduction and, where it applies, a deferred capacity upgrade. A battery sized purely for peak shaving can often also earn grid-flexibility revenue in the hours it would otherwise sit idle.

A worked illustration

A worked illustration, not a customer result: if a site’s metered demand peaks at 550 kW and a 300 kW battery holds it below 450 kW across the weekday peak, the agreed capacity can in principle fall by up to 100 kW. What that is worth depends on the capacity charge in your contract, which is why the first step is to read it, alongside a year of half-hourly data.

The peak shaving calculator applies the published 2026/27 red, amber and green unit rates and the capacity charge for the four National Grid Electricity Distribution areas to your own peak and battery size, and the East Midlands guide shows that region’s figures in one place.

Compliance and grid connection

A peak-shaving system of this size needs a full G99 application to the District Network Operator (G98 covers only the smallest installations). The DNO may grant the connection with an export or import limitation scheme, or require Active Network Management, and the G99 timescale varies widely, so the application should go in early. The installer should design to the IET Code of Practice for Electrical Energy Storage Systems and the relevant standards, with fire, thermal, detection and separation design, all under CDM 2015, and engage your insurer before energisation.

One point specific to peak shaving: once the battery is reliably holding your maximum demand down, your agreed import capacity is likely larger than you now need. Renegotiating the agreed kVA downward removes excess available-capacity charges — a saving that continues every month for the life of the system, and one many businesses never claim. Confirm your installer is MCS-certified for battery storage and NICEIC, RECC or TrustMark registered.

Who it suits — and who it doesn’t

Peak shaving suits sites with a spiky, predictable daytime load: manufacturers, process plants, cold stores, and any operation where several large loads coincide inside the red-band window. It is at its most compelling where the site is also capacity-constrained, because deferring a DNO reinforcement adds a large saving on top of the unit-rate reductions. The more pronounced and repeatable your peaks, the better the case.

It is a weaker fit where demand is flat and predictable with no real peaks, there is little to shave, so the unit-rate saving is thin. Sites with a generous, under-used import capacity and modest peak charges may find the payback drifts past ten years. If your main objective is overnight cost-shifting rather than clipping spikes, energy arbitrage is the better-matched strategy, and where resilience is the priority, backup power and resilience should lead the design. Whichever leads, the half-hourly data comes first, and it shows whether storage stacks up for your site.

Frequently asked questions

How much can peak shaving actually cut off our bill? It depends entirely on the shape of your peaks, your charging bands and your capacity agreement, so there is no honest typical figure. The exact figure depends entirely on the shape of your peaks, which is why the figure has to come from twelve months of your own half-hourly meter data before anyone quotes.

Can a battery really help us avoid a DNO capacity upgrade? Yes. Because the battery supplies the extra power during peaks, a behind-the-meter system lets a constrained site draw more during peak periods than its agreed import capacity, so you can add EV chargers, plant or shifts without a costly grid reinforcement. The avoided upgrade is often the single largest part of the business case.

Does commercial peak-shaving storage qualify for 0% VAT? No. Commercial battery storage is standard-rated at 20% VAT, though any VAT-registered business recovers it in full. The 0% VAT relief applies only to domestic and charitable buildings (until 31 March 2027). On the capital allowances side, the Annual Investment Allowance lets you deduct 100% of the cost in year one up to £1m. Above £1 million a year, a company claims the 50% first-year allowance on the special-rate spend; this site treats a battery as special-rate plant, as HMRC treats solar panels, and our tax guide explains why.

What a peak shaving service includes, and how to judge a peak shaving supplier

A peak shaving service is an engineering and control contract, not a battery sale. It covers twelve months of half-hourly data analysis, an agreed target peak, an EMS control strategy tuned to red-band DUoS half-hours, the G99 application and any G100 limitation scheme, and support to renegotiate your agreed import capacity once measured peak demand falls.

Five workstreams separate a service from a supply-only quote. Data analysis sets the target peak from your own consumption rather than a rule of thumb. Control strategy defines what the energy management system does in every half-hour, including which peaks it defends. Scheduling maps discharge onto the red DUoS band and recharge onto the cheapest hours, because the Triad regime has ended and the value now sits in avoiding red-band half-hours rather than three winter peaks. Grid compliance covers the G99 application, usually the critical path, plus G100 import or export limitation where the DNO asks for it. Commercial follow-through means going back to the supplier and the DNO to cut the billed kVA once the lower peak is proven in the data.

Three things give a box sale away. The quote leads with a price per kWh instead of a target peak in kW. Flexibility income is quoted as a fixed annual number rather than as site-specific and never guaranteed. And nobody has asked for your half-hourly data before pricing the job.

We are independent of suppliers and manufacturers, so the specification follows your load profile, not a stock list. Start with the commercial battery storage cost ranges, then the design detail behind a battery energy storage system, and what the idle hours can earn through grid services revenue. Set the target peak from your half-hourly data before anyone talks about hardware; send us your details and we reply by email.

See also

• commercial power backup in Milton Keynes
• battery storage installation across Nottinghamshire
• commercial solar battery storage in Hampshire