Peak shaving is the practice of using stored energy to cap the highest spikes in a site's grid demand, and for large UK commercial users it targets one of the fastest-growing lines on the bill: demand charges that reach 7.26 pounds per kVA a month on supplies above 100kVA in 2025/26 (Socomec, 2025). For a heavy industrial load that translates into six-figure annual charges before a single unit of energy is priced.
For installers, peak shaving is where a commercial battery earns its payback. Great Britain now runs around 10GW of grid battery capacity delivering roughly 18GWh (Carbon Commentary, 2026), and the same physics scales down to a factory, cold store or fleet depot. This guide covers what peak shaving is, how it differs from load shifting, how to size a system for it, and the grid steps a compliant install needs.
Key Takeaways
- Peak shaving caps demand spikes; load shifting moves energy across the day. Most commercial batteries do both, but you size them differently.
- The saving comes from avoided demand and capacity charges, which the 2025/26 Access Significant Code Review pushed sharply higher for many sites (NUS Consulting, 2025).
- Size the battery to the peak power in kW you need to clip and the length of that peak, not to annual energy throughput.
- UK factory paybacks for standalone commercial storage commonly land between 6 and 10 years (Solar Panels for Factories, 2026).
- Any commercial system above 3.68kW per phase needs Distribution Network Operator approval under G99 before it energises.
What is peak shaving?
Peak shaving means discharging a battery during a site's short demand peaks so the meter never records the full spike, then recharging when demand and prices fall. It works because UK network charges reward a lower measured peak. Grid battery capacity has grown fast enough to overtake nuclear for the first time (Drax, 2025).
On a commercial site the peaks are usually brief. A chiller bank starting, a paint line ramping, or the first shift powering up can double the site's draw for twenty minutes. The battery covers that window so the grid connection and the bill are sized to the average, not the worst moment. That is the whole idea, and it is why half-hourly meter data matters more than any rule of thumb.
There is a wider market signal behind this too. The UK grid-scale fleet added a record 4GWh in 2025 and keeps growing, which tells you the economics of clipping peaks now stack up at every scale (Energy-Storage.News, 2025). What works for a 50MW grid asset also works for a 300kWh battery in a factory switchroom: both exist to keep the measured peak down.
Peak shaving vs load shifting: what is the difference?
Peak shaving targets the maximum power drawn in any half hour to cut demand and capacity charges. Load shifting moves the timing of energy use, charging when unit rates are low and discharging when they are high, to cut the energy portion of the bill. Both use the same hardware, but the control logic and battery sizing differ.
The distinction decides how you size and program the system, so it is worth setting out plainly:
- Peak shaving. Goal is a lower kVA peak. Sized to peak power and peak duration. Saves on demand and capacity charges.
- Load shifting. Goal is cheaper energy timing. Sized to the energy moved per cycle. Saves on unit rates and time-of-use spreads.
- Combined. Most 2026 commercial installs run both modes, with the energy management system prioritising demand-charge events over arbitrage.
In practice we see the sharpest peaks cluster in the DUoS red band on winter weekday evenings, which is also when unit rates spike, so the two strategies often fire the battery at the same moment (TotalEnergies, 2025).
How does peak shaving cut a commercial energy bill?
The saving lands in the non-energy charges. Distribution Use of System charges are billed by time band, with the costly red band on weekday late afternoons and evenings, and capacity is charged on the site's measured peak. The 2025/26 Access SCR rebalanced these: standing charges fell by an average 72% while capacity charges more than doubled for many bands (NUS Consulting, 2025).
That rebalancing is the reason peak shaving pays better in 2026 than it did three years ago. When the network recovers more of its cost through a measured peak, clipping that peak is worth more. Well-sized systems can remove a large share of a site's demand-charge exposure, and the April 2026 DUoS update left average charges broadly flat while widening the regional gap (Drax, 2025).
Three charge lines respond to a shaved peak:
- DUoS red-band consumption. Discharging through the red window cuts the priciest distribution units.
- Capacity charge (kVA). A lower agreed capacity reduces the fixed monthly kVA line.
- Capacity Market and DUoS bands. Avoiding the measured peak protects against future band-driven rises.
Sizing a battery energy storage system for peak shaving
Size to power and duration, not to yearly consumption. Pull twelve months of half-hourly data from the site's meter, find the recurring peaks, and set the discharge power in kW to the amount you want to clip. Then multiply by the peak duration to get the energy in kWh. A 200kW clip lasting 90 minutes needs roughly 300kWh of usable capacity.
Two field checks stop oversizing. First, look at how often the true peak occurs; if it is a handful of half hours a month, a smaller battery cycled hard beats a large one sitting idle. Second, confirm the inverter can deliver the clip power continuously, because peak shaving is a power problem before it is an energy one. Our single line diagram guide shows how to keep the protection and metering unambiguous.
A workable sizing sequence:
- Extract half-hourly demand for a full year and plot the load duration curve.
- Set the target peak (kVA) you will not exceed, and read off the clip power in kW.
- Multiply clip power by the longest typical peak duration for usable kWh, then add depth-of-discharge headroom.
- Check inverter continuous power and round to a real product size.
What does peak shaving battery storage cost in 2026?
Installed commercial storage runs from about 350 pounds per kWh at large factory scale to 700 to 1,200 pounds per kWh for smaller systems, as fixed engineering, grid and civil costs spread differently across the size range (Elum Energy, 2026). The UK grid-scale market added 4GWh in a record 2025, and that volume keeps pushing prices down (Energy-Storage.News, 2025).
Indicative 2026 ranges to frame a quote:
- Small commercial, 30 to 100kWh. Around 700 to 1,200 pounds per kWh installed (Elum Energy, 2026).
- Large factory scale, 500kWh and above. Closer to 350 pounds per kWh as fixed costs spread (Solar Panels for Factories, 2026).
- Payback. Standalone commercial storage commonly returns in 6 to 10 years in UK factories (Solar Panels for Factories, 2026).
- Demand-charge reduction. A well-sized system targets a large share of the site's kVA exposure (Socomec, 2025).
These are planning figures, not quotes. The real number depends on the DNO connection, switchgear, fire strategy and whether solar or a hybrid inverter is part of the scheme (hybrid inverter guide).
Grid connection and compliance for commercial peak shaving
A commercial battery above 3.68kW per phase is a G99 job, so the DNO application and any witness test come before energisation, not after. Build the protection settings, export limit and single line diagram into the design early, because a late DNO condition can force a hardware change. Government statistics show grid-scale storage scaling nationally, and the same connection rules apply to a factory unit (gov.uk, 2025).
Safety documentation is the other half. An electrical energy storage install should follow the IET Code of Practice for the fire strategy, ventilation and isolation, and the DNO paperwork should match what is actually installed. Getting the application right first time is covered in our G99 application guide, and the storage safety detail sits in our IET Code of Practice guide.
Where peak shaving works best
The strongest cases share a shape: a high measured peak relative to average load, a site above 100kVA where demand charges bite, and predictable peak timing. Manufacturing with shift starts, cold storage, EV charging hubs and large retail all fit. A flat commercial roof often carries solar to pair with the battery, which changes the sizing and the return (flat roof solar).
Reonic's design tools let installers model the load profile, battery size and DNO paperwork for a commercial peak-shaving job in one place, so the proposal reflects the real half-hourly data rather than a rule of thumb. The weaker cases are flat-profile sites with no sharp peak, where load shifting or solar self-consumption usually returns more than shaving ever will.
Frequently asked questions
Is peak shaving the same as load shifting?
No. Peak shaving cuts the maximum power drawn in any half hour to reduce demand and capacity charges, while load shifting moves energy use to cheaper times to reduce unit-rate costs. The same battery can do both, but peak shaving is sized to peak power and duration, whereas load shifting is sized to the energy moved each cycle.
How big a battery do I need for peak shaving?
Size it to the peak you want to clip. Take the clip power in kW from the site's half-hourly data, multiply by the typical peak duration for usable kWh, then add depth-of-discharge headroom. A 200kW clip over 90 minutes needs roughly 300kWh usable. Confirm the inverter can deliver the clip power continuously, since shaving is a power problem first.
Does a peak shaving battery need DNO approval?
Yes, for almost every commercial case. Anything above 3.68kW per phase needs a G99 application to the Distribution Network Operator, with protection settings and often a witness test agreed before energisation. Submit the application early, because a late DNO condition on export limit or protection can force a change to switchgear or inverter configuration.
Can solar power peak shaving?
Solar helps but rarely does the job alone, because peaks do not always align with generation. A hybrid system charges the battery from solar when it is available and from cheap grid energy overnight, then discharges through the demand peak. On a flat commercial roof this pairing improves the return, though the battery, not the array, is what clips the measured peak.
How much can peak shaving save a UK business?
It depends on the demand charge and the peak shape. With supplies above 100kVA facing charges around 7.26 pounds per kVA a month, clipping a large peak can remove a substantial slice of the kVA bill, and typical UK factory paybacks fall between 6 and 10 years. Sites with flat load and no sharp peak see little benefit.
