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Energy Storage System

An energy storage system (ESS or BESS) is a battery bank with an inverter, packaged for mobile or temporary deployment, that stores electrical energy and delivers it as AC power on demand. On job sites these units run silent overnight loads, shave generator runtime in hybrid setups, and provide clean power where noise or emissions rules constrain engines.

Modèles

24–1,303 kVA across cataloged models

Power output

Marques

Fonctionnement

The battery bank — most commonly lithium-based in current mobile units — feeds a power-electronic inverter that produces stable AC output at the required voltage and frequency. A battery management system supervises cell voltages, temperature, and state of charge, protecting the pack from over-charge and over-discharge. In hybrid configurations the ESS pairs with a generator: the battery carries light and overnight loads, and the system starts the engine only when load rises or the pack needs recharging. This cuts fuel burn, noise, and engine hours compared to running a diesel set continuously at low load.

Types et variantes

Portable battery energy storage units: Compact wheeled or skid units delivering AC power for tools, lighting, and trailers without engine noise or exhaust.
Trailer-mounted BESS: Larger towable systems that substitute for mid-size generators on noise- or emissions-restricted sites.
Hybrid generator-storage systems: Storage paired with a diesel set under shared controls, running the engine only when needed.
UPS-class systems: Storage engineered for uninterrupted transfer, protecting critical loads such as IT and life-safety equipment during outages.

Spécifications clés

Spécification	Plage typique	Signification
Power output	24–1,303 kVA across cataloged models	The inverter's rating caps how much load the unit can serve at once; like generators, kW output equals kVA times power factor.
Energy capacity	Rated in kWh, model dependent	Capacity sets how long the unit sustains a given load before recharging; runtime equals usable kWh divided by average load in kW.
Recharge source	Grid connection, generator, or solar input depending on configuration	Determines how the system fits into a site power plan and how quickly it returns to full charge.
Output configuration	Single- and three-phase AC at standard site voltages, model dependent	Must match the distribution equipment and loads the unit will serve.

Comment l'industrie le dimensionne

Storage systems are sized on two axes: power (kW/kVA, the instantaneous load the inverter can carry) and energy (kWh, how long that load can be sustained). A unit is selected by matching inverter rating to peak connected load and battery capacity to the load profile between recharge opportunities. In hybrid duty the storage is typically sized to carry the site's overnight and idle loads so the generator can shut down entirely for those hours.

Applications

Silent overnight power for site offices, security systems, and lighting
Hybrid pairing with diesel generators to cut fuel use and engine hours
Temporary power on emissions- or noise-restricted urban sites
Backup power for critical loads during planned outages
Powering electric tools and equipment charging where grid service is absent

Sécurité et opération

Lithium battery systems carry thermal-runaway risk; follow manufacturer clearances and never operate a unit with visible pack damage.
Treat the AC output like any generator output: distribution must be grounded, bonded, and GFCI-protected per the NEC.
Charge and stage units per NFPA 855 separation guidance where systems are grouped or stored indoors.
Only qualified personnel should service the DC side; pack voltages remain lethal with the inverter off.

Normes et certifications

UL · UL 9540 / UL 9540A: Safety standard for energy storage systems and the test method for thermal-runaway fire propagation.
NFPA · NFPA 855: Installation standard for stationary energy storage systems, including separation and capacity limits.
UL · UL 1973: Safety standard for the battery packs used in stationary and motive ESS applications.
NFPA · NFPA 70 (NEC), Article 706: Code requirements for energy storage system installations.

Questions fréquentes

How is a battery energy storage system different from a generator?

A generator converts fuel to power continuously; an ESS delivers stored energy silently with no emissions at the point of use, but must be recharged. Power rating governs both, while runtime on an ESS is fixed by battery capacity rather than tank size.

What does a hybrid generator-storage setup accomplish?

The battery carries light loads and overnight demand, so the diesel engine runs only at efficient load levels and shuts off otherwise. The result is lower fuel burn, fewer engine hours, and quiet nights, with the generator recharging the pack while it runs.

How is runtime estimated for a storage unit?

Divide usable battery capacity in kWh by the average load in kW. A load profile with high peaks but a low average runs far longer than the peak figure alone suggests, which is why load profiling matters more for storage than for generators.