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184–266 kWh

Commercial energy storage systemFortress Power

Fortress Power MINI-90-135-xxx-480

184–266 kWh · 90 kW · Lithium Ion · direct PV input · 4 configurations

UL 9540UL 1741 SBCEC listed · Feb 1, 2024

Nameplate energy184–266 kWh
Continuous power90 kW
Round trip (AC)80%
ChemistryLithium Ion

Overview

CEC Energy Storage System List

MINI-90-135-xxx-480: 184–266 kWh nameplate energy; 90 kW continuous; lithium ion; accepts solar panels directly (DC-coupled).

Models & configurations

CEC Energy Storage System List · 4 listings

Model	Energy	Power	Grid voltage	Round trip	CEC listed
MINI-90-135-184-480	184 kWh	90 kW	480 V	80%	Apr 11, 2024
MINI-90-135-204-480	204 kWh	90 kW	480 V	80%	Feb 1, 2024
MINI-90-135-245-480	245 kWh	90 kW	480 V	80%	Feb 1, 2024
MINI-90-135-266-480	266 kWh	90 kW	480 V	80%	Feb 1, 2024

Capacity & power

CEC Energy Storage System List

Nameplate energy (CEC)184–266 kWh
Rated power (CEC)90 kW
Max continuous discharge (CEC)90 kW
Full-power discharge timeabout 2.9 h at full power
Round-trip efficiency (AC-AC)80%
ChemistryLithium Ion
Grid connection480 V

Safety listings

CEC Energy Storage System List

UL 9540 (energy storage system)Certified by Intertek
Certificate date & editionMar 14, 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)Yes (with conditions)
JA12 declaration (Title 24)Yes
JA12 control strategiesBasic, TOU, Advanced DR
Last CEC updateFeb 21, 2025
Monitor Key Data schedulingYes

Questions & answers

How much energy does the Fortress Power MINI-90-135-xxx-480 store?

184–266 kWh nameplate, per the California Energy Commission list.

Is the MINI-90-135-xxx-480 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.