Fortress Power eFlex Max DC energy storage system
The Fortress Power eFlex Max DC energy storage system is a home battery range from Fortress Power with 4 models. Models store 5.38 kWh – 21.5 kWh in Lithium Iron Phosphate cells. Rated AC power 5.12 kW – 13.82 kW. Listed and verified: UL 9540. Sold in United States.
Specifications
- Capacity
- 5.38 kWh – 21.5 kWh
- Battery chemistry
- Lithium Iron Phosphate
- Rated AC power
- 5.12 kW – 13.82 kW
- Models in this range
- 4
Backup and savings with the Fortress Power eFlex Max DC energy storage
From 5.38 kWh to 21.5 kWh of storage, the Fortress Power eFlex Max DC energy storage stores daytime solar for the evening and night, and with a backup-capable installation keeps a home running through a power cut. It delivers 5.12 kW of AC power (up to 13.82 kW in larger configurations), enough for most of a home's circuits at once.
One full charge covers about 18% of an average US home's daily electricity use of 29.6 kWh.
Its LiFePO4 (lithium iron phosphate) cells are the long-life chemistry of home energy storage: rated for thousands of cycles and more thermally stable than other lithium-ion types.
| Load | Runs for about |
|---|---|
| Essential circuits: fridge, lights, internet, phone charging (about 500 W) | 9.7 hours |
| An average US home (about 1.23 kW around the clock) | 3.9 hours |
Estimates. Electricity prices: U.S. Energy Information Administration, average household electricity use.
Product details
- Product type
- Home battery
- Brand
- Fortress Power
- Category
- Home Battery Storage
- Sold in
- United States
- Listed in
- California Energy Commission
Models (4)
| Model | Nominal capacity | Usable capacity | AC power | Certificate |
|---|---|---|---|---|
| eFlex Max DC energy storage system-5.4P1 | 5.376 kWh | 5.12 kVA | ||
| eFlex Max DC energy storage system-10.8P2 | 10.752 kWh | 10.24 kVA | ||
| eFlex Max DC energy storage system-16.2P3 | 16.128 kWh | 13.824 kVA | ||
| eFlex Max DC energy storage system-21.6P4 | 21.504 kWh | 13.824 kVA |
Certifications
| Certification | Market | Status | Reference | Valid until |
|---|---|---|---|---|
| UL 9540 | United States and Canada | ✓ Verified 19 October 2026 | Intertek |