Battery storage on a commercial site
A battery does not make energy. It moves it in time. That only pays if one hour costs more than another.
What it actually is
A battery charges when electricity is cheap or when your own generation exceeds what the building is using, and discharges when it is expensive or when demand peaks.
It stores solar that would otherwise export, avoids expensive tariff periods, and trims the peaks that drive capacity charges.
A battery does not make electricity. It moves it in time. It charges when power is cheap, or when your own generation is running ahead of what the building is using, and it discharges when power is expensive or when the site is drawing its hardest.
That means a battery only earns money when one hour genuinely costs more than another, or when you have surplus generation that would otherwise leave the site for a low export price. If your tariff is flat, your load is flat and you have no array, a battery has nothing to work with.
There are three separate jobs a commercial battery can do, and a proposal should be clear about which one it is buying. It can store your own generation instead of exporting it. It can shift consumption out of expensive tariff periods. It can shave the short sharp peaks that set your capacity and network charges.
The third one is underrated. On many industrial sites the largest lever is not the unit rate at all. It is the agreed capacity and the charges that sit on top of it, and a modest battery that trims a peak can be worth more than a large one that chases a tariff spread.
Which buildings it suits, and which it does not
It suits sites with a sharp daily peak, a time of use tariff, or an existing array exporting a meaningful share of what it makes.
It suits you less if your load and tariff are flat and you have no generation.
- Manufacturing with heavy start up loadsGood fitShort, sharp peaks when plant starts are exactly what a battery is good at flattening.
- Sites with a large existing arrayGood fitIf a meaningful share of generation is being exported, storing it instead is real value. Check the export share first, from data.
- Cold storage and process coolingDependsThe thermal mass of the store is itself a battery. Shifting compressor run times may achieve much of the same result for nothing.
- Offices on a time of use tariffDependsThe case rests on how wide the difference between periods is and how much load sits in the expensive window.
- Sites at their agreed capacityDependsA battery can defer a costly connection upgrade. Compare that avoided cost, not just the tariff saving.
- Small even load sites on a flat tariffRarelyNothing to arbitrage, nothing to store, no peak to shave.
- Buildings with no plant space or tight fire separationRarelyEnclosures need clearance, ventilation and separation distances. Congested urban sites often cannot give them.
What it typically costs and saves
- Installed cost
- from £400 to £600 per usable kWh
- Typical duration
- one to four hours at peak output
What drives the variation
- •Usable capacity, which is not the same as nameplate capacity. Ask which one the price is quoted against.
- •Power rating relative to capacity. A battery that has to discharge fast costs more per unit stored.
- •Whether it is alternating current or direct current coupled to an existing array.
- •Civils. A concrete base, bollards, fencing and a cable run are all real cost.
- •Switchgear, protection and any network approval for the connection.
- •Whether an operating contract or a control platform is bundled in and for how many years.
How this appears on your building
What decides whether it works on your building
The shape of your load, not the total
Half hourly data is the whole basis of a battery case. It shows when you peak, how long the peak lasts and how much energy sits inside it. An annual consumption figure tells you nothing a battery can use.
Your tariff structure
Day and night rates, seasonal periods and capacity charges all matter. Read the bill properly, including the standing and network elements, because that is often where the recoverable money is.
Existing or planned generation
Exported solar is the cheapest thing a battery can be filled with. If you have an array, get the export figures from the monitoring before anyone sizes a battery.
Cycles and warranty
A battery is warranted for a number of cycles or a throughput of energy, whichever comes first. A strategy that cycles twice a day uses that warranty twice as fast. Ask how the proposed strategy sits against the warranty.
Space, weight and fire separation
Enclosures have separation distances from the building line and the boundary, and they need access for maintenance. Insurers may have their own requirements. Establish those before a location is agreed.
Whether the site could take part in flexibility markets
Some sites can earn from making capacity available to the network. It is a real revenue line and it is not available everywhere. If a proposal counts on it, ask which service, with whom, and on what contract length.
How long it takes and what it disrupts
Before delivery
Load analysis, sizing, siting, fire and insurance sign off, and network approval where required. The analysis stage is where the value is decided, so do not compress it.
Site works
The base and cable route are the noisy part. They happen outside the building and can usually be done around normal operations.
Installation and tie in
The enclosure arrives as a unit. Connection needs a planned electrical shutdown, which is short and scheduled.
The first months
Control strategy is tuned against real data after commissioning. Expect to review performance against the model and adjust. Ask who does that and whether it is included.
What usually goes wrong or gets missed
Sized on annual consumption
It ends up too large to fill or too small to matter. Only load shape can size a battery correctly.
Bought as an accessory to solar without checking the export
If the array is already consuming almost everything it makes, there is nothing for the battery to store.
Degradation left out of the model
Capacity falls over the life of the asset. A payback built on year one capacity for fifteen years overstates the return.
Round trip losses ignored
You do not get back everything you put in. A model that treats stored energy as free after charging is wrong.
Flexibility revenue treated as certain
Market income varies and contracts are not indefinite. If the case only works with that revenue, the case is fragile. Ask to see it without.
- •It is sized on annual consumption rather than load shape, so it is too big to fill or too small to matter.
- •It is bought as an add on to solar without checking whether much is being exported at all.
- •Degradation and warranted cycles are left out of the payback.
What to ask an installer
- 01Have you sized this from my half hourly data, and can I see the load profile you used?
- 02Is the price quoted against usable capacity or nameplate capacity?
- 03Which job is this battery doing: storing generation, shifting tariff, or shaving peaks?
- 04What is the warranted number of cycles, and how many will your proposed strategy use each year?
- 05What round trip efficiency and what annual degradation have you assumed?
- 06What does the case look like with no flexibility market income at all?
- 07What are the fire separation distances, and has my insurer been asked?
- 08Who controls the battery after commissioning, and what does that cost each year?
- 09What happens at end of life, and who removes and disposes of it?
How it interacts with other measures
With solar
The natural pairing, but only after the array has run long enough to show a real export figure. Buying both together sizes the battery on a forecast rather than a measurement.
With EV charging
A battery can absorb charging peaks and keep the site inside its agreed capacity, which can be cheaper than upgrading the connection. Compare the two costs directly.
With voltage optimisation and lighting
Both reduce consumption. Do them first, because a smaller load usually means a smaller battery.
With an EPC rating
Storage does not reduce the modelled energy use of a building, so it will not move a band. Judge it on the bill alone.
Common questions
Is a commercial battery worth it without solar?
Sometimes. If you have a time of use tariff with a real difference between periods, or sharp peaks driving capacity charges, a battery can pay on its own. If your load and tariff are both flat, it cannot.
How big a battery do I need?
That is set by the shape of your load, not by your annual consumption. The energy inside your peak periods, and how long those peaks last, decide capacity and power rating.
How long does a commercial battery last?
It is warranted by cycles or energy throughput as well as by years, so the answer depends on how hard it is worked. A strategy that cycles more often shortens the calendar life.
Can a battery avoid a grid connection upgrade?
Often yes. If new load such as EV charging would push you past your agreed capacity, a battery that covers the peak can be cheaper than reinforcing the connection. Get both prices before deciding.
Where can a battery be sited?
Usually outside in an enclosure, with clearance from the building line and the boundary, access for maintenance, and agreement from your insurer. Space and separation rule out some tight urban sites.
Related reading
Where these figures come from
Show the provenance
- Installed cost: from £400 to £600 per usable kWh
- UK commercial market, 2026.
- Typical duration: one to four hours at peak output
- UK commercial battery systems are specified at one to four hours of storage at peak output.
Grid electricity is taken at 20 to 27 pence per kWh, from 2026 UK commercial rates.
The figures on this page are modelled ranges for UK commercial buildings, not a quote for yours. Add your building and we will model it on your own roof, load and rating.