Big Battery EG4 FlexBOSS21 12kW (21kPV) Hybrid Inverter

The latest development from the EG4 team, the FlexBOSS21 is a cutting-edge, split-phase hybrid inverter designed to be the keystone of any residential or commercial power system. With an incredible 21kW PV input capacity and an array of advanced features, the FlexBOSS21 provides reliable performance day in and day out, in both on-grid and off-grid settings.
The FlexBOSS21 is one of the highest capacity inverters on the market today, featuring 3 MPPTs supporting up to 5 strings, providing superior flexibility for multi-orientation solar arrays, and the ability to handle 90A of grid feed-through at 120/240VAC, ensuring robust grid-tied capabilities. Plus, the FlexBOSS21 seamlessly integrates with EG4’s GridBOSS MID power gateway for a cost-effective, streamlined setup, helping to reduce installation time and system startup costs, and when you pair these two units together in your system, you’re able to utilize the smart load management, AC coupling, and generator support features if needed.
But that’s not all. EG4 understands the value of enhanced safety and visibility when it comes to your power, and the FlexBOSS21 spares no expense, coming equipped with responsive rapid shutdown, ground fault monitoring, and arc fault protection, all backed by industry-leading safety certifications, and with EG4’s updated monitoring software, you get access to remote management, mobile notifications, and convenient Wi-Fi connectivity for your system.
Combining efficiency, scalability, and cutting-edge technology, the FlexBOSS21 is a top-tier solution, with a safety-first design, for those seeking a reliable, powerful inverter to anchor their energy system. Whether for residential or commercial applications, its advanced features and versatile design provide unmatched value and peace of mind. Elevate your energy independence and power your future with the EG4 FlexBOSS21 Hybrid Inverter today!


Features







3 MPPT Inputs


Remote Monitoring


Smart Load Control


AC Coupling Function


Integrated UPS Module


Built-In Circuit Breakers


Seamless Switching In Under 20ms


High-Frequency Split-Phase Output


Advanced Parallelability up to 192kW


Seamless Integration With GridBOSS MID







Suitable For







48V Battery Systems


Residential Solar Systems


AC Coupled UPS Systems


Off-Grid Backup Systems


Emergency Power Systems


Commercial ESS




AC INPUT












AC Voltage:
120V AC / 240V AC


AC Frequency:
60 Hz / 50 Hz


Max. Continuous AC Current:
50A @ 240V AC


Max. AC Input Power:
12000W


Max. AC Bypass:
90A








AC GRID OUTPUT












Operating Voltage Range:
180 - 270V AC


Output Voltage:
120V AC / 240V AC


Max. Continuous Output Current:
66.7A


Output Frequency:
60 Hz / 50 Hz


Output Power (without PV):
12000W @ 240V


Output Power (with PV):
16000W @ 240V


Power Factor:
0.99 (Full Load)


Reactive Power Adjustment Range:
-0.8 ~ 0.8 Leading Adjustable


Total Harmonic Distortion:
<5% (Full Load)


Transfer Time:
10 - 20 ms (Single) / 20 ms (Parallel)








AC BACKUP / UPS OUTPUT












Max. Continuous Output Current:
50A


Output Voltage:
120V AC / 240V AC


Output Power:
12000W @ 240V AC


Max. Output Power:
24000W (0.5 sec) / 18000W (1 sec)15000W (6 min) / 13200W (12 min)


Operating Frequency:
60 Hz / 50 Hz


Total Harmonic Distortion Voltage:
<5%


Transfer Time:
10 - 20 ms (Single) / 20 ms (Parallel)








PV INPUT












No. of MPPTs:
3


Inputs per MPPT:
2 (MPPT 1 & 2) / 1 (MPPT 3)


Max. Input Current:
26A (MPPT 1 & 2) / 15A (MPPT 3)


Max. Short Circuit Input Current:
31A (MPPT 1 & 2) / 19A (MPPT 3)


DC Input Voltage Range:
100 - 600V DC


Start Up Voltage:
100V DC


MPPT Operating Voltage Range:
120 - 440V DC


MPPT Voltage:
360V DC


Max. Utilized PV Array Power:
21000W


Max. PV Input:
25000W


Max. Efficiency:
94 - 97%


Idle Consumption:
<80W (Normal) / <60W (Standby Mode)








BATTERY












Nominal Voltage:
48V DC


Voltage Range:
40 - 60V DC


Max. Charge / Discharge Power:
12000W


Recc. Battery Capacity per Inverter:
>300 Ah








OPERATING ENVIRONMENT












Operating / Storage Temperature Range:
-13ºF - 140ºF (-25ºC - 60ºC)


Altitude:
<6,561 ft (2000 m)


Relative Humidity:
0 - 100%


Typical Noise Emission:
<50 dB @ 3 ft


Protection Rating:
IP65 / NEMA 4X


Communications:
RS485 / CANBus / WiFi


Max. Parallel Connections:
16








DIMENSIONS












Weight:
88 lbs (40 kg)


Depth:
11.3 in (287 mm)


Width:
22.3 in (567 mm)


Height:
30.5 in (775 mm)



 
Spec SheetUser ManualUL1741 Certificate

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