A cold store uses electricity all day and all night, so it is easy to assume a battery has nothing to shift. Continuous refrigeration does not mean constant grid demand. Where the tariff has a demand charge, a battery can lower it by carrying part of the load through the intervals that set the charge. Whether that pays depends on the site’s data and tariff rules. This article is for operators of cold stores, food processors and distribution centres anywhere in the National Electricity Market, with a South Australian site as the worked example.
Key points
- A battery is worth it at a cold store when the tariff has a demand charge or a wide time-of-use gap, the site has grid peaks the battery can cover for their full length, and there is somewhere to recharge without creating a new peak. It is not worth it on savings alone when demand stays high for hours or the tariff gives nothing to shift.
- Cold-store peaks are site-specific. They move with weather, stock movements, cooling needs and equipment schedules, and they do not necessarily fall in the evening.
- A battery supplies part of the site’s load from stored energy. It does not reduce the refrigeration load itself.
- In Aivy’s modelled cold-store day, running the battery to a plan cut the half-hour that sets the demand charge by 44% compared with the same battery in default mode.
- Cold-chain requirements come first. Backup capability, reserve settings and control permissions are confirmed for each project. Stored energy on its own does not protect a site through an outage.
Why a cold store’s bill is bigger than its energy use suggests
A cold store pays for the energy it uses, in kWh, and on many tariffs also for its demand, in kW. Refrigeration is an ongoing load, but not a flat one. Door openings let in warm air, incoming goods need pulling down to temperature, and defrost cycles add load of their own. How much each matters depends on the site and its controls. None of it means every compressor ramps up together, or that the peak comes in the evening.
On a demand tariff, one high interval inside the charging window can affect the bill for a month, and on some networks for longer. The rules differ by network, so check four things for your tariff: the measurement interval, the charging window, the demand units and the reset rules. The peak that counts is the one recorded at the grid connection, and that can differ from the refrigeration load.
Hot weather pushes refrigeration demand up through the day. At a site with solar, grid draw can also rise as the sun drops in the late afternoon, with no change in equipment load. Lay the interval data over the tariff’s charging window to see which peaks matter. A spike in the wholesale price does not change the rate for a customer on a fixed retail tariff.
What a battery changes on a cold-store bill
A battery changes the demand and time-of-use parts of the bill. It carries part of the existing load; it does not shrink the refrigeration requirement. With enough discharge power and stored energy, it holds grid draw under a chosen cap through the intervals that matter. Depending on the site and tariff, that creates value in three places:
- Demand charge. The battery discharges through the intervals that set the site’s demand charge, keeping grid draw under the cap. The saving depends on the tariff and on how much of the peak the battery can take.
- Time-of-use energy. Where the price gap is wide enough, the battery charges in cheap periods and supplies the site in dear ones, after allowing for losses.
- Solar. Where the roof makes more than the site is using at that moment, the battery stores the surplus for later. A cold store with a high daytime load may use all of its solar directly, so check for a surplus rather than assuming one.
What stays the same is also worth knowing. The daily supply charge, metering and other fixed charges do not move. On a flat-rate tariff with no demand charge, the battery has little to work with, and a different tariff may be the better first step. We say so when that is the case.
When it is worth it, and when it is not
Four checks tell you whether a battery could be worthwhile. Run them on bills and interval data that cover normal weeks, busy weeks and the hot season. Any saving still has to be weighed against installation, service and replacement.
- A demand tariff, or a wide time-of-use gap. Look for a demand or capacity line on the bill, or a big difference between peak and off-peak rates. Either one gives the battery something to shift.
- Grid peaks the battery can actually reduce. Find the peaks inside the tariff’s charging window and pick a grid cap the site can hold. Timing, height and length of the peak all matter.
- Enough power and energy for the whole peak. A two-hour peak needs a battery that can cover the load above the cap for two hours, after losses, operating limits and any backup reserve.
- Somewhere to charge from. Midday solar surplus, or a cheap off-peak window, so the battery refills without creating a new peak.
The case is weaker when demand stays high for long stretches, when recharging would create a new billed peak, or when the tariff gives little for shifting energy. Backup can be worth having in its own right, if the system is designed for it, but savings alone may not pay for it.
A South Australian cold store, modelled
Aivy modelled a cold store with rooftop solar over 28 days on a network demand tariff, with the same battery run two ways: left in its default mode, storing surplus solar and covering shortfalls on its own, and run to Aivy’s plan. In this modelled day the grid peak falls in the evening. That is the profile we chose to show the method, not a claim about when cold stores peak. In default mode the battery spends its charge through the afternoon and is low when the peak arrives. Run to a plan, it charges under a grid cap through the middle of the day and holds that charge for the evening.
The half-hour that sets the demand charge came in 44% lower than default mode. The figures are modelled, not measured at a customer site. The same method gave 19% at an office and 57% at a two-shift factory; the three charts are on the Commercial & Industrial page. The comparison was not built to test outage performance or backup duration, and says nothing about them.
Same site, same solar, same battery in both runs. The difference is timing: when the battery charges, how much it keeps back and which half-hours it covers.
Cold chain, backup and what Aivy controls
Cold-chain requirements come before any saving. If the site needs backup, the design has to confirm the critical loads, how long they must run, the battery’s usable energy and output power, and the compressors’ starting current. The system also has to be built to run during a grid outage, with the right isolation and transfer arrangements. A reserve setting on its own gives none of that. Once a reserve is agreed, how it is treated during bill optimisation and VPP events is written down and verified for the project.
Aivy’s job is the battery: when it charges, when it discharges and how much it keeps. Which equipment is connected, and whether Aivy can see it or change it, is agreed for each project. That includes compressors, alarms, door systems and temperature set points. Seeing an alarm is not the same as changing or disabling it, and the scope says which it is. Operating limits, and what kind of strategy change needs the operator’s approval, are agreed the same way.
For longer outages a standby generator or another backup supply may still be needed. A battery can bridge the gap while a generator starts only where the equipment is compatible and the transfer sequence has been designed and commissioned for it. Do not assume seamless supply.
How to check your own site
- Pull a year of bills. Note the billed demand, its units and the rate. Ask the retailer how the charging window and reset rules work, rather than guessing from the bills.
- Get interval data. Ask the retailer for a NEM12 file. Compare typical, busy and hot weeks against the tariff’s demand window, with solar output and operating schedules alongside if you have them.
- Measure the gap. Choose a grid cap and add up the power above it, interval by interval, across the peak. Allow for losses and operating limits, then check the battery’s discharge power and when it can recharge.
- Settle backup first. If the site needs backup, confirm the critical loads, the duration, compressor starting power and the transfer arrangement with the system designer. Agree the reserve before counting what is left for savings.
If you would rather not do the arithmetic, send us a bill and a month of interval data. We will come back with the peak that sets your demand charge, what a battery could carry, and an honest answer on whether it is worth it on your tariff.
Questions people ask
Can a battery keep a cold store running through a blackout?
Only if the system is designed for backup: enough usable energy and output power for the loads you choose, including compressor starting, plus the isolation and transfer arrangements to run off-grid. A reserve setting alone is not enough. Long outages may still need a standby generator, and bridging a generator start takes compatible equipment, a designed transfer sequence and commissioning checks.
Does Aivy control refrigeration equipment or temperature set points?
Aivy controls the battery’s charging and discharging. What else is connected, and whether that access is for monitoring or control, is agreed for each project and written into the scope. That covers compressors, temperature set points, alarms and door systems. Being able to see data does not give permission to change settings.
Does a cold store need solar for a battery to make sense?
No. The demand saving comes from discharging through the site’s peaks and recharging without creating a new billed peak, and the battery can also shift purchases into cheaper tariff periods. Solar supplies charging energy where the roof makes more than the site is using, but that surplus has to be checked, not assumed.
Which states does Aivy operate in?
Across the National Electricity Market: Queensland, New South Wales, the Australian Capital Territory, Victoria, South Australia and Tasmania.
Written by the Aivy Energy team in Adelaide. Aivy runs batteries for businesses and operates solar and battery power stations across the National Electricity Market: Queensland, New South Wales, the ACT, Victoria, South Australia and Tasmania. Figures are from Aivy’s own modelled scenarios unless a source is named.
