# Energy storage: UPS batteries & BESS

Part ID: 7.11 · Layer 7 (Electrical: power distribution (grid to rack))

Battery systems that store energy for UPS ride-through, plus larger grid-scale battery energy storage systems (BESS) that a campus can use for peak shaving, load smoothing, or backup at a scale beyond a single UPS.

UPS batteries (7.10) are sized to bridge the short gap until generators (7.13) take over, using li-ion, VRLA, or newer chemistries depending on cost, footprint, and safety requirements. Grid-scale BESS is a different scale of the same underlying technology, sited alongside or near the campus substation (7.01) rather than inside the building, and used for purposes closer to what a utility or independent power producer would use it for: shifting load away from peak grid demand, smoothing the output of an on-site or co-located generation source, or providing a buffer that lets a campus start operating before its full generation or interconnection capacity is complete. Power conversion systems (PCS) and inverters sit between the battery cells and the AC grid or campus distribution in both applications, converting stored DC energy to usable AC power. Because grid-scale BESS is deployed at a scale that draws on the same lithium-ion and battery-materials supply chain as electric vehicles and utility storage, campus buildout competes for cell and pack capacity with those larger markets. For investors, the split between UPS-scale batteries (a mature, well-supplied market) and grid-scale BESS (a newer, faster-growing use case for data centers specifically) matters more than the category as a whole.

**AI delta:** AI campuses are pairing grid-scale BESS with their interconnection to smooth GPU load swings and to draw down stored energy during peak periods, a use case largely new to data centers rather than inherited from conventional IT backup power.

## Companies

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Confidence tags: disclosed = company/filing statement; reported = trade press or partner list; inferred = taxonomy lead.