Fortress Power eSpire 233

Name: Fortress Power eSpire 233
Brand: Fortress Power

233–900 kWh · 125–128 kW · Lithium Ion · 5 configurations

UL 9540CEC listed · Apr 3, 2023

Overview

CEC Energy Storage System List

eSpire 233: 252 kWh usable energy; 125–128 kW continuous; lithium ion.

CEC Energy Storage System List · 5 listings

Model	Energy	Power	Grid voltage	Round trip	CEC listed
eSpire 233	233 kWh	125 kW	480 V	—	Apr 3, 2023
eSpire 300	300 kWh	125 kW	480 V	92%	Feb 21, 2024
eSpire 466	466 kWh	125 kW	480 V	—	Apr 21, 2023
eSpire 600	600 kWh	125 kW	480 V	92%	Feb 21, 2024
eSpire 900	900 kWh	125 kW	480 V	92%	Feb 21, 2024

CEC Energy Storage System List

CEC Energy Storage System List · Fortress Power datasheet

CEC Energy Storage System List

UL 9540 (energy storage system)Certified by Intertek
Certificate date & editionJan 3, 2023 · Ed. 2 : 2020
UL 9540A (fire propagation test)Yes
Other standards on datasheetUL 1741, IEEE 1547, UL 9540A, UL 9540, UL 1973, IEC 62619

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

CEC Energy Storage System List

CEC Energy Storage System List · Fortress Power datasheet

manufacturer documents

How much energy does the Fortress Power eSpire 233 store?

252 kWh usable, per the manufacturer datasheet.

Can you add more eSpire 233 units?

Yes — up to 15 units per system.

Can the eSpire 233 be installed outdoors?

Installation location per the datasheet: indoor/outdoor.

Is the eSpire 233 UL 9540 certified?

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

California Energy Commission — Energy Storage System List, data as of Oct 7, 2026. Manufacturer-reported values confirmed by CEC against certificates.
Fortress Power — datasheet eSpire 233 Data Sheet.
Fortress Power — document library on the manufacturer’s website (links above).