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500 kWh

Commercial energy storage systemESS Tech

ESS Tech EW-75-xxx-DC-B

500 kWh · 90 kW · Iron Flow Battery

UL 9540CEC listed · Mar 1, 2024

Nameplate energy500 kWh
Continuous power90 kW
ChemistryIron Flow Battery

Overview

CEC Energy Storage System List

EW-75-xxx-DC-B: 500 kWh nameplate energy; 90 kW continuous; iron flow battery.

Capacity & power

CEC Energy Storage System List

Nameplate energy (CEC)500 kWh
Rated power (CEC)75 kW
Max continuous discharge (CEC)90 kW
Full-power discharge timeabout 5.6 h at full power
ChemistryIron Flow Battery

Safety listings

CEC Energy Storage System List

UL 9540 (energy storage system)Certified by Intertek
Certificate date & editionMay 18, 2023 · Ed. 2 : 2020

UL 9540 certifies the whole storage system; UL 9540A is the fire-propagation test that fire codes ask for indoors and near walls.

California grid & code compliance

CEC Energy Storage System List

UL 1741 SB (IEEE 1547-2018)No
UL 1741 SA (Rule 21)No
CSIP (IEEE 2030.5)No
JA12 declaration (Title 24)No
Monitor Key Data schedulingNo

Questions & answers

How much energy does the ESS Tech EW-75-xxx-DC-B store?

500 kWh nameplate, per the California Energy Commission list.

Is the EW-75-xxx-DC-B UL 9540 certified?

Yes — the CEC list shows UL 9540 certification (certified by intertek).

Sources

California Energy Commission — Energy Storage System List, data as of Oct 7, 2026. Manufacturer-reported values confirmed by CEC against certificates.