Technology guide, established
Backup power and energy storage
Backup power keeps IT running through grid faults: static UPS with batteries, rotary or flywheel UPS, diesel or gas generator sets, and increasingly battery energy storage that can also support the grid. Ratings mix kW, kVA and MWh, so power and energy must never be added together.
Also called: UPS, static UPS, rotary UPS, DRUPS, generators, gensets, BESS, battery energy storage, flywheel
What it is
Static UPS (for example ABB MegaFlex DPA 1,000 to 2,000 kW) bridge the gap until generators start. Rotary and diesel rotary UPS (Piller UNIBLOCK up to 50 MW systems) combine flywheel and engine. Gensets (mtu 20V4000 DS4000 rated 3,950 to 4,000 kVA) carry longer outages. BESS store energy in MWh and deliver power in MW.
Units and roll-ups
kVA is apparent power, kW real power, MWh energy. Genset ratings differ by duty (standby, prime, continuous, data centre continuous). Never sum MW with MWh, and never sum standby with continuous ratings.
Corporate status matters
Check supplier health. Powin, a BESS integrator, filed for Chapter 11 in June 2025, its key assets went to FlexGen and its estate is in liquidation. Fleet support and warranty assignment should be confirmed in writing.
Sourcing considerations
Emissions permits for gensets, fuel type (diesel, HVO, gas), start time, step load acceptance, battery chemistry and fire safety codes, runtime basis, and lifecycle service.
Questions to ask suppliers
- Rating basis (kW vs kVA, standby vs continuous)
- Runtime and energy (MWh) at stated load
- Start time and step load performance
- Fuel, emissions limits and permits
- Battery chemistry, fire testing and spacing
- Warranty holder if the supplier is acquired or insolvent
Suppliers with public evidence
- Vertiv
- Schneider Electric
- Eaton
- ABB
- Socomec
- Kohler Energy (Rehlko)
- Huawei Digital Power
- Delta Electronics
- Piller Power Systems
- Mitsubishi Electric
- Caterpillar
- Cummins
- Rolls-Royce Power Systems (mtu)
- Wärtsilä
- Powin
- GE Vernova
Listed alphabetically. Inclusion means a public source shows the company offers products or services for this technology. It is not a ranking or endorsement. Compare these suppliers.
Sources (5), last checked 18 Oct 2026
- ABB MegaFlex DPA (opens in a new tab), ABB, published 23 Mar 2026, accessed 18 Oct 2026
- Piller UNIBLOCK (opens in a new tab), Piller, accessed 18 Oct 2026
- mtu 20V4000 DS4000 (opens in a new tab), Rolls-Royce Power Systems, accessed 18 Oct 2026
- FlexGen completes acquisition of Powin assets (opens in a new tab), FlexGen, published 19 Aug 2025, accessed 18 Oct 2026
- Powin Liquidating Trust (opens in a new tab), Powin Liquidating Trust, accessed 18 Oct 2026
Last checked 18 Oct 2026 by CoolPower Index research (automated, sourced). Report a correction.