FOXESS ECS4000-H4

15.9 kWh · 11.5 kW · Lithium Iron Phosphate

UL 1973CEC listed · May 11, 2023

Usable energy21.4 kWh
Continuous power11.5 kW
ChemistryLithium Iron Phosphate

Overview

CEC Battery List

ECS4000-H4: 21.4 kWh usable energy; 11.5 kW continuous; lithium iron phosphate.

Capacity & power

CEC Battery List

Nameplate energy (CEC)15.9 kWh
Total energy (datasheet)11.9–23.8 kWh
Usable energy21.4 kWh
Depth of discharge90%
Max continuous discharge (CEC)11.5 kW
Full-power discharge timeabout 1.9 h at full power
Round-trip efficiency (datasheet)95%
ChemistryLithium Iron Phosphate
Cell formatprismatic
Battery voltage (DC, nominal)115.2–403.2 V

How long can it power your home?

Cali-Graf calculation

Average home load	Runtime from full
0.5 kW	≈ 42.9 h
1 kW	≈ 21.4 h
2 kW	≈ 10.7 h
3 kW	≈ 7.1 h
11.52 kW (full continuous power)	≈ 1.9 h

Runtime = 21.4 kWh usable (datasheet) ÷ load. A typical home averages 1–2 kW; air conditioning and EV charging use much more. Inverter and wiring losses shorten it.

Charging from solar in Southern California

NLR PVWatts v8 · Cali-Graf calculation

City	December	June
Los Angeles	6.7 kW	3.9 kW
Palmdale	6.2 kW	3.6 kW
Chula Vista	5.7 kW	4.1 kW
Huntington Beach	6.3 kW	4.4 kW
Riverside	6.4 kW	3.8 kW
Santa Clarita	6.3 kW	3.7 kW

Solar array size that refills the battery from empty in one average day, before the home uses any of it (NLR PVWatts v8, 20° south roof).

Stacking & expansion

CEC Battery List · FOXESS datasheet

Max units per systemup to 7 units
Max system capacity27.8 kWh

Installation & environment

CEC Battery List · FOXESS datasheet

Installation locationindoor/outdoor
Operating temperature−10 to 55 °C
Mountingstand

Safety listings

CEC Battery List

UL 1973 (stationary battery)Certified by CSA Group
Certificate date & editionOct 28, 2022 · Ed. 3 : 2022
UL 9540A (fire propagation test)Yes
Other standards on datasheetUL 9540A, UL 9540, UL 1973, UN 38.3, FCC

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

Full specifications

CEC Battery List · FOXESS datasheet

Communicationcan, rs485
Manufacturer websitefox-ess.com

Compare with similar batteries

CEC Energy Storage System List

Battery	Energy	Continuous power	Chemistry	Warranty	SoCal permits
LG Energy Solution RESU 10H Prime	9.6–16 kWh	5 kW	Lithium Ion	—	127
Qcells Q.SAVE	9–18 kWh	5.5–11.1 kW	Lithium Iron	10 years	30
EG4 Electronics WP-16/280-1AWLL	14.3 kWh	10.2 kW	Lithium Iron Phosphate	10 years	5
Tigo Energy TSB	9 kWh	3.5–5.2 kW	Lithium Iron Phosphate	11 years	2
FOXESS ECS4000-H5	25 kWh	14.4 kW	Lithium Iron Phosphate	—	1
RNG International Renogy X	20 kWh	10 kW	Lithium Iron Phosphate	10 years	1

Same segment, similar capacity; each row from the same sources.

Questions & answers

How much energy does the FOXESS ECS4000-H4 store?

21.4 kWh usable, per the manufacturer datasheet.

How long can the ECS4000-H4 power a home?

About 21.4 hours at an average 1 kW load from a full charge (21.4 kWh usable); higher loads shorten it.

Can you add more ECS4000-H4 units?

Yes — up to 7 units per system.

Can the ECS4000-H4 be installed outdoors?

Installation location per the datasheet: indoor/outdoor.

Sources

California Energy Commission — Energy Storage System List, data as of Oct 7, 2026. Manufacturer-reported values confirmed by CEC against certificates.
California Energy Commission — Battery List, data as of Oct 7, 2026.
FOXESS — manufacturer datasheet “ENERGY CUBE ECS4000-H2 / H3 / H4 / H5 / H6 / H7 FOX ENERGY CUBE”.
NLR (formerly NREL) — PVWatts v8, NSRDB PSM v3 typical-year weather for Los Angeles, Palmdale, Riverside, Santa Clarita, Chula Vista, Huntington Beach.
Cali-Graf calculations — formulas and inputs are shown next to each calculated value (efficiency from area, temperature-corrected voltages, string sizing, energy estimates).