Fortress Power FlexTower - Fortress Power DuraRack

The Fortress Power FlexTower is a pre-wired, all-in-one energy storage enclosure that combines a hybrid inverter and battery rack into a single unit. It houses the Envy 12kW inverter in the top enclosure and up to four eFlex or eFlex MAX batteries in the DuraRack below, providing up to 21.6 kWh of scalable storage.

Key Features

• All-in-One Design: Pre-wired enclosure with integrated busbars, pre-cut knockouts, and 200A grid pass-through -- no separate backup subpanel needed
• Scalable Storage: DuraRack holds up to four eFlex or eFlex MAX batteries (up to 21.6 kWh per unit); multiple FlexTowers can be combined for larger systems
• Built for Any Environment: Carbon steel construction with NEMA 3R rating and IP65 water/dust resistance for indoor or outdoor installation
• Round-Trip Efficiency: Over 98% battery efficiency with CEC-rated inverter performance
• Thermal Management: Built-in cooling fans for the inverter; DIN-rail heater support in the DuraRack for cold-climate battery operation
• LCD Touchscreen: On-unit display for real-time energy flow monitoring, plus remote app control

Certifications

Top Enclosure: UL1741, UL1741-SA, UL1973, UL9540(A). DuraRack: UL9540, UL9540(A), UL1973, CEC, SGIP. These certifications streamline permitting and ensure full regulatory compliance.

Applications

Supports whole-home backup, off-grid power, Time-of-Use (TOU) optimization, and Virtual Power Plant (VPP) participation. Compatible with both AC and DC coupling for integration with new or existing solar arrays.