0.1% of recent U.S. home systems use Fortress Power home batteries.
Fortress Power
Status: Operating; small private company.
Company
USA (Pennsylvania)
Capacity and power
5.4-18.5 (eVault Max 18.5, eFlex 5.4) kWh usable, Depends on inverter (Envy 12 kW hybrid) kW continuous, LFP, round-trip ~95-98% DC
Design
DC (48V low-voltage)
Whole-home backup
Yes with suitable inverter
Typical installed price
$8,000-$15,000 (estimate; get quotes)
Warranty
years: 10; retention: 70%; throughput: Check
Price tier
budget-mid
Risks to weigh
Small company
Specifications as stated by the manufacturer; confirm on the current datasheet and warranty document.
Fortress Power home batteries on the CEC certified list
28 certified models, 5–56.32 kWh. Smallest to largest. See all models.
Model
Capacity
Power
Chemistry
Round-trip
eFlex 5.4
5 kWh
5.4 kW
Lithium Iron Phosphate
—
eFlex Max 5.4
5.4 kWh
5 kW
Lithium Iron Phosphate
—
eForce 9.6
9.6 kWh
9.36 kW
Lithium Iron Phosphate
—
Avalon HV BAT 9.8P1M2
9.8 kWh
4.8 kW
Lithium Iron Phosphate
—
Avalon HV BAT 14.7P1M3
14.7 kWh
7.2 kW
Lithium Iron Phosphate
—
eBoost DC Energy Storage System 16 P1
16.08 kWh
12.8 kW
Lithium Iron Phosphate
—
eVaultMax
18.43 kWh
9.2 kW
Lithium Iron Phosphate
—
Avalon HV BAT 19.6P1M4
19.6 kWh
9.6 kW
Lithium Iron Phosphate
—
FP-Nano-S4-I
20.48 kWh
20.48 kW
Lithium Iron Phosphate
—
FP-Nano-S4-O
20.48 kWh
20.48 kW
Lithium Iron Phosphate
—
Avalon HV BAT 24.5P1M5
24.5 kWh
12 kW
Lithium Iron Phosphate
—
FP-Nano-S5-I
25.6 kWh
25.6 kW
Lithium Iron Phosphate
—
Choosing equipmentA well-installed mid-tier system beats a premium brand installed badly. Ask quotes to name exact models, compare warranties in writing, and check that the company backing a 25-year warranty is financially healthy. Compare your quotes.