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280–840 kWh

Commercial energy storage systemFortress Power

Fortress Power eSpire xxx HP

280–840 kWh · 128 kW · Lithium Ion · 3 configurations

UL 9540UL 1741 SBCEC listed · Feb 21, 2024

Nameplate energy280–840 kWh
Continuous power128 kW
Round trip (AC)92%
ChemistryLithium Ion

Overview

CEC Energy Storage System List

eSpire xxx HP: 280–840 kWh nameplate energy; 128 kW continuous; lithium ion.

Models & configurations

CEC Energy Storage System List · 3 listings

Model	Energy	Power	Grid voltage	Round trip	CEC listed
eSpire 280 HP	280 kWh	125 kW	480 V	92%	Feb 21, 2024
eSpire 560 HP	560 kWh	125 kW	480 V	92%	Feb 21, 2024
eSpire 840 HP	840 kWh	125 kW	480 V	92%	Feb 21, 2024

Capacity & power

CEC Energy Storage System List

Nameplate energy (CEC)280–840 kWh
Rated power (CEC)125 kW
Max continuous discharge (CEC)128 kW
Full-power discharge timeabout 6.7 h at full power
Round-trip efficiency (AC-AC)92%
ChemistryLithium Ion
Grid connection480 V

Inverter & compatible equipment

CEC Energy Storage System List

Direct PV inputNo
Battery modules in this systemF4979

Safety listings

CEC Energy Storage System List

UL 9540 (energy storage system)Certified by Intertek
Certificate date & editionJan 26, 2024 · 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)Yes
UL 1741 SA (Rule 21)No
CSIP (IEEE 2030.5)No
JA12 declaration (Title 24)Yes
JA12 control strategiesBasic, TOU, Advance DR
Last CEC updateApr 22, 2024
Monitor Key Data schedulingNo

Questions & answers

How much energy does the Fortress Power eSpire xxx HP store?

280–840 kWh nameplate, per the California Energy Commission list.

Is the eSpire xxx HP 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.