EG4 | FlexBOSS18 Hybrid Inverter | 18kW PV / 12kW AC | 48V Split-Phase | UL1741 | INV031

EG4 FlexBOSS18 Hybrid Inverter

The EG4 FlexBOSS18 is a 48V all-in-one hybrid inverter that accepts up to 18,000W of solar and delivers 12,000W of continuous split-phase AC output (120/240V or 120/208V). With dual MPPTs, a 90A grid pass-through, built-in rapid shutdown and arc-fault protection, and an IP65 / NEMA 4X outdoor-rated enclosure, it is built to power whole-home solar and battery backup systems, with or without the grid.

Key Features

• 18kW PV Input: Two MPPTs with two strings each, 100–600VDC input range
• 12kW Continuous Output: Split-phase 120/240VAC or 120/208VAC, with peak power up to 20kW
• 90A Grid Pass-Through: Supports whole-home backup and grid-tied operation
• 10kW Battery Charge/Discharge: Works with EG4 and BigBattery ETHOS batteries in closed-loop communication
• Scalable: Parallel up to 10 units for larger systems
• Built-In Safety: Rapid shutdown, ground-fault, and arc-fault protection
• Outdoor Rated: IP65 / NEMA 4X enclosure, -13°F to 140°F operating range
• Smart Monitoring: Wi-Fi monitoring with mobile alerts, plus RS485, CANbus, and 4G options
• GridBOSS Ready: Pairs with the EG4 GridBOSS MID for load management and generator integration

Specifications

• Rated AC Output: 12,000W @ 240VAC / 12,000W @ 208VAC
• Peak Power: 20,000W (0.5s), 15,000W (1s), 12,500W (6 min), 11,000W (12 min)
• Rated Output Current: 50A @ 240V (66.7A max)
• AC Output Voltage: 120/240VAC or 120/208VAC split-phase
• Frequency: 60Hz (50Hz selectable)
• Grid Pass-Through: 90A
• Max AC Input Power: 13,000W
• Transfer Time: 20ms default (10ms configurable)
• Max Recommended PV Input: 18,000W
• MPPTs: 2 (2 inputs each)
• PV Input Voltage Range: 100–600VDC (200VDC start-up)
• MPPT Operating Range: 120–440VDC
• Max Usable Input Current: 26A per MPPT
• Max Short-Circuit Current: 31A per MPPT
• Battery Voltage: 48VDC (40–60VDC range)
• Max Battery Charge/Discharge Power: 10,000W
• Recommended Battery Capacity: 300Ah or more per inverter
• Efficiency: 97.5% PV-to-grid, 94.5% PV-to-battery, 94% battery-to-grid
• Idle Consumption: Less than 65W
• Parallel Capability: Up to 10 units
• Communication: RS485, CANbus, Wi-Fi, 4G
• Enclosure Rating: IP65 / NEMA 4X
• Operating Temperature: -13°F to 140°F (-25°C to 60°C)
• Topology: High-frequency, transformerless
• Dimensions (W x D x H): 22.8 x 11.2 x 30.5 in
• Weight: 115 lbs
• Certifications: UL 1741, CEC listed, UL 9540 system certified with closed-loop communication

10-Year EG4 Manufacturer Warranty

Backed by a 10-year EG4 manufacturer warranty and lifetime USA-based technical support.

Manuals and Resources

• Spec Sheet
• User Manual