Battery Energy Storage in Data Centers
A UPS battery is sized to bridge seconds or minutes. A larger energy storage system can do more, and raises its own design and safety questions.
Possible uses
- Backup bridging: carry the load until generators start, as UPS batteries do.
- Peak shaving: reduce demand charges by discharging at peak times.
- Renewable firming: store surplus generation for later use.
- Grid services: where the market and utility allow it.
Design questions
- Energy (kWh) and power (kW) needed for each use, and the number of cycles.
- Where it connects: behind the UPS (DC), at LV or at MV.
- Protection, fault levels and interaction with generators. See short circuit basics.
- Fire safety, spacing and ventilation, and compliance with the applicable codes.
- Battery chemistry and life. See lithium-ion vs VRLA.
See also UPS battery sizing for the basic bridge-to-generator case.
Written by the Vision Matrix Institute editorial team. Worked examples use stated, illustrative assumptions; check them against your project data, the applicable standards and manufacturer datasheets before use.
Frequently Asked Questions
What is a battery energy storage system?
A system of batteries with power conversion and controls that stores electrical energy and releases it on demand, at a larger scale and duration than a typical UPS battery.
What can BESS do for a data center?
Possible uses include peak shaving, supporting the grid, smoothing renewable output and extending backup time, depending on the design and the local market.
Does BESS replace a generator?
Not usually. Energy capacity and the cost of long-duration storage mean generators typically remain for extended outages, though designs vary.
What are the safety concerns?
Fire and thermal runaway risk for lithium-ion systems, ventilation, separation from critical spaces and compliance with the relevant codes such as NFPA 855 where it applies.
Want to learn this properly?
This topic is covered in depth in our Electrical Design – Data Center Specialist program.
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