EG4 | FlexBOSS21 Hybrid Solar Inverter | 21kW PV / 16kW AC | Split-Phase | 4-MPPT | Scalable | Remote Wi-Fi Monitoring | INV027

EG4 FlexBOSS21 Hybrid Inverter The EG4 FlexBOSS21 Hybrid Inverter is a high-capacity, next-generation energy solution designed for advanced residential and commercial solar systems. With up to 21,000W of usable PV array capacity and 16,000W of split-phase 120/240V output power, the FlexBOSS21 provides the performance and flexibility needed for demanding on-grid, hybrid, and off-grid applications. Its 48V battery architecture and high-power design make it well suited for large-scale energy storage and backup applications. The FlexBOSS21 features 3 MPPT inputs supporting up to 5 strings, allowing for flexible solar array configurations and efficient energy harvesting. It supports a 100–600V DC input range, with an MPPT operating range of 120–440V DC, and can utilize up to 21,000W of PV array power with a maximum recommended PV input of 25,000W. With a maximum efficiency of 97% for PV-to-grid, 94.5% for PV-to-battery, and 94% for battery-to-grid, the inverter is designed to make efficient use of available solar and stored energy. Powerful Output & Grid Integration The FlexBOSS21 provides 12,000W of nominal output power without PV and up to 16,000W of output power with PV at 240V. It supports 120/240V AC split-phase output and offers a 90A maximum AC bypass, allowing it to accommodate high-demand electrical systems. The inverter also delivers peak power capabilities of up to 24,000W for 0.5 seconds, 18,000W for 1 second, and 15,000W for 6 minutes, providing additional capacity for demanding loads and startup requirements. With 90A grid feed-through, the FlexBOSS21 can integrate with larger electrical systems while supporting advanced energy management. Its 0.99 power factor at full load, adjustable reactive power range of -0.8 to 0.8, and less than 5% total harmonic distortion help provide stable and efficient power delivery. Advanced Solar & Battery Management The inverter operates with a 48V DC nominal battery voltage and supports a voltage range of 40–60V DC. It provides up to 12,000W of maximum battery charge/discharge power and recommends a battery capacity of more than 300Ah per inverter. The system is compatible with 48V battery systems and supports BigBattery ETHOS and EG4 Batteries with closed-loop communication. The FlexBOSS21 also supports AC coupling, making it useful for system upgrades and retrofits. When integrated with the EG4 GridBOSS MID, it enables advanced capabilities such as smart load management, generator support, and intelligent energy distribution. Smart Monitoring & Safety Built-in Wi-Fi connectivity, RS485, CANBus, and remote monitoring provide convenient access to system information and performance data. Users can monitor their energy system and receive mobile alerts, helping provide greater visibility and control. For enhanced safety, the FlexBOSS21 includes rapid shutdown, ground fault protection, and arc fault protection. Its IP65/NEMA 4X protection rating helps protect the unit in demanding environments. The inverter is designed to operate and be stored in temperatures ranging from -13°F to 140°F (-25°C to 60°C) and at altitudes up to 6,561 feet (2,000 meters). System Flexibility With support for up to 16 units in parallel, the FlexBOSS21 can be scaled for larger energy requirements. Its high-frequency, transformerless design, combined with flexible solar, battery, grid, and generator integration, makes it suitable for a wide range of modern energy systems. Key Specifications 21,000W maximum utilized PV array power 25,000W maximum recommended PV input 16,000W output with PV at 240V 12,000W nominal output without PV 3 MPPTs supporting up to 5 strings 48V battery system 12,000W maximum battery charge/discharge power 90A maximum AC bypass 120/240V AC split-phase output 97% maximum PV-to-grid efficiency Up to 16 units in parallel IP65 / NEMA 4X protection RS485 / CANBus / Wi-Fi communications 88 lbs (40 kg) 22.3" W × 30.5" H × 11.3" D 10-Year EG4 Manufacturer Warranty The EG4 FlexBOSS21 Hybrid Inverter is backed by a 10-year EG4 manufacturer warranty, providing long-term coverage and added confidence in the inverter's reliability and performance.