Data Centres

If your constraint is the interconnection queue rather than the equipment, storage is the fastest capacity you can buy. This page covers where a BESS actually helps a data centre, where it does not, and what it takes to get one permitted and commissioned in Ontario.

The problem is the grid, not the generator

Data centre power planning used to be a question of redundancy. It is now a question of availability: whether the utility can deliver the load at all, and when.

Interconnection queues in North America held more than 2,200 GW of planned capacity in mid-2026. New transmission lines take six to seven years to build, and long-distance routes can take up to fifteen. A facility that needs 30 MW in eighteen months is not waiting on switchgear. It is waiting on a utility study.

That pressure is visible in what operators are actually building. Roughly 56 GW of on-site generation and storage capacity was in planning as of early 2026, around 30% of all planned data centre builds. In some markets the utility now rewards it directly: the Southwest Power Pool’s HILLGA framework offers connection agreements in under 90 days to data centres that arrive with their own generation.

Ontario is not SPP, and we will not pretend the numbers transfer. But the mechanism does: a site that can shape its own load is a smaller, faster, cheaper connection to approve.

Four things a BESS does for a data centre

1. Bridges the interconnection gap

Storage lets a facility energise at a lower contracted capacity and ride through the gap between load growth and grid capacity. You size the connection for average demand and let the battery absorb the peaks, instead of sizing the connection for a peak that occurs a few hours a month.

This is the use case with the largest financial swing, because the alternative is not a cheaper battery. It is waiting.

2. Augments or replaces UPS strings

A conventional VRLA UPS gives you five to fifteen minutes of ride-through and is sized for one job. A lithium BESS at the same footprint typically gives you considerably more runtime, tolerates far more cycles, and, critically, can earn money on the days nothing goes wrong, by shaving demand or shifting energy.

Two honest caveats. A BESS is not a drop-in UPS replacement: static transfer and sub-cycle response still belong to the UPS layer unless the system is explicitly designed for it. And a battery doing daily cycling is a different warranty conversation from a battery sitting in float. We size for one duty or the other and say which.

3. Cuts demand and Global Adjustment exposure

Data centres are close to the ideal peak-shaving load: high, flat, predictable, and instrumented. In Ontario, a Class A facility’s Global Adjustment bill is set by its contribution to the province’s five highest demand hours in the year. A battery that discharges through those five hours changes the bill for the following twelve months.

We cover the mechanics in detail on the Ontario peak shaving page.

4. Holds frequency and power quality

Inverter-based storage responds in milliseconds, faster than any rotating machine. For sites with sensitive process load or weak feeders, that is often the quiet justification that survives the business case review even when the arbitrage does not.

What it does not do

A BESS is not a replacement for generation. Two to four hours of storage covers a demand peak or a utility event; it does not carry a 30 MW hall through a multi-day outage. Sites that need that still need gensets, and the honest design pairs the two. The battery handles the frequent, short, expensive events and the generator handles the rare, long ones. Our generator offset calculator models exactly that split.

Sizing: the three numbers that decide everything

Every data centre BESS conversation reduces to three inputs.

• Power (MW). How much you need to displace at once. Set by the peak you are shaving or the load you are bridging.
• Energy (MWh). How long you need to hold it. Set by the duration of the event: a 2-hour peak window needs roughly twice the energy of a 1-hour one at the same power.
• Cycles per year. How often it runs. It is the input most often left out of a quote, and the one that determines whether the warranty holds and whether the economics are real.

A facility shaving five Ontario peak hours a year is a fundamentally different machine from one arbitraging daily. Same enclosure, different cells, different thermal design, different price. Anyone quoting you a $/kWh number before asking about cycles is quoting a container, not a system.

Safety and permitting: how NFPA 855 applies to a Canadian data centre

NFPA 855 is the installation standard for stationary energy storage, and it is referenced in almost every serious BESS review. It does not automatically govern a Canadian installation. Whether it applies, and which edition, comes from the adopted provincial and municipal requirements, your insurer, the project specification and the authority having jurisdiction, or AHJ.

Settle that code basis before the site layout is fixed. On a data centre campus the AHJ conversation reaches setbacks, access routes, ventilation and where the block can physically sit. All of those are cheap to move on a drawing and expensive to move on a pad.

The direction of the 2026 edition is more weight on how an installation behaves under severe fire conditions, which changes what a buyer should be reading:

• Set the hazard mitigation analysis scope early. An HMA is site-specific. Certificates and laboratory reports feed it and do not replace it. Establish who prepares it, what data the supplier provides and when the AHJ expects to review the approach.
• Read the fire-test scope, not the cover page. ANSI/CAN/UL 9540A is a staged method addressing the cell, module, unit or installation level. Older unit-level results stay useful, but they are not the installation-level, large-scale test described in the newer framework, and “9540A tested” on its own settles nothing.
• Ask how the evidence maps to your configuration. Certification and test evidence apply to named configurations. If the cell, module count, enclosure, fire system or spacing changes, someone has to document why the earlier evidence still carries across.
• Put emergency planning in the contract. Response planning and training belong in project scope with named owners and delivery dates, not in a folder assembled after energization.
• Bring fire-protection input in during design. For a larger or unusual installation the AHJ may expect interpretation by a qualified fire-protection professional. Identify that person before permit stage.

The practical consequence is that the documentation conversation starts earlier than it did two years ago. A certificate proves that something specific was evaluated. It does not prove that your site was.

How BX approaches data centre projects

BX Energy Systems designs and integrates containerized lithium systems for commercial, industrial and utility sites across Canada. For data centres that usually means a 2.5 to 5 MWh LFP block, outdoor-rated, sited and documented for an Ontario AHJ.

If you are early enough that the question is still “does this even work for our load”, the fastest way to find out is fifteen minutes with one of our engineers and a copy of your interval data.

Book a 15-minute sizing call

Common questions

Can a BESS replace our UPS entirely?

Sometimes, but not by default. Sub-cycle transfer and the isolation function still sit with the UPS layer unless the storage system is specifically designed and certified for it. The more common outcome is a BESS behind the UPS that extends runtime and earns its keep on demand charges.

How long does a data centre BESS take to deploy?

Equipment lead time is usually the shorter half. Utility approval, AHJ fire-safety review and site civil work dominate the schedule. Start the fire-safety documentation conversation at the same time as the electrical one.

What size do we need?

It depends on whether you are bridging a connection, shaving a peak, or extending ride-through. Those give very different answers for the same building. Our peak shaving calculator will get you an order of magnitude in about three minutes from one utility bill.

Is lithium safe next to a data hall?

With current LFP chemistry, correct separation and a documented fire-safety package, yes. The useful procurement test is whether the supplier can produce fire-test evidence for the configuration you are actually buying, rather than a datasheet and a family certificate. Siting is usually outdoors in a containerized block regardless, which simplifies the analysis considerably.