Fortress Power Avalon-ESS-5P3-xx.xP1M3

Name: Fortress Power Avalon-ESS-5P3-xx.xP1M3
Brand: Fortress Power

44.1 kWh · 15 kW · Lithium Ion · direct PV input

UL 9540UL 1741 SBCEC listed · Mar 1, 2024

Overview

CEC Energy Storage System List

Avalon-ESS-5P3-xx.xP1M3: 44.1 kWh nameplate energy; 15 kW continuous; lithium ion; accepts solar panels directly (DC-coupled).

CEC Energy Storage System List

NLR PVWatts v8 · Cali-Graf calculation · CEC Energy Storage System List

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).

CEC Energy Storage System List

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

Battery	Energy	Continuous power	Chemistry	Warranty	SoCal permits
EG4 Electronics PP-16/280A3-18K1-AWLL	43 kWh	10.4–12 kW	Lithium Iron Phosphate	10 years	—
EG4 Electronics PP-16/280A3-18K2-AWLL	43 kWh	20.8–24 kW	Lithium Iron Phosphate	10 years	—
Power Center Duracell	14–42 kWh	5 kW	Lithium Iron Phosphate	—	—
BYD BATTERY-BOX PREMIUM HVL (US)	12–32 kWh	7.5–20 kW	Lithium Iron Phosphate	10 years	1

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

How much energy does the Fortress Power Avalon-ESS-5P3-xx.xP1M3 store?

44.1 kWh nameplate, per the California Energy Commission list.

Is the Avalon-ESS-5P3-xx.xP1M3 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.
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).