EG4 FlexBOSS21 Hybrid Solar Inverter | 21kW PV / 16kW AC | Split-Phase | 4-MPPT | Scalable | Remote Wi-Fi Monitoring
EG4 FlexBOSS21 Hybrid Solar Inverter | 21kW PV / 16kW AC | Split-Phase | 4-MPPT | Scalable | Remote Wi-Fi Monitoring - Image 2
EG4 FlexBOSS21 Hybrid Solar Inverter | 21kW PV / 16kW AC | Split-Phase | 4-MPPT | Scalable | Remote Wi-Fi Monitoring - Image 3
EG4 FlexBOSS21 Hybrid Solar Inverter | 21kW PV / 16kW AC | Split-Phase | 4-MPPT | Scalable | Remote Wi-Fi Monitoring - Image 4

Product Summary:

The EG4 FlexBOSS21 is a high-capacity split-phase hybrid inverter engineered for advanced residential and commercial energy systems. With 12kW output and up to 21,000W of PV input, it delivers powerful performance in both on-grid and off-grid setups. Equipped with 3 MPPTs for up to 5 strings, 90A grid feed-through at 120/240VAC, and seamless integration with the EG4 GridBOSS MID gateway, it offers superior flexibility, smart load management, AC coupling, and generator support. Safety features include rapid shutdown, ground fault and arc fault protection, and industry-leading certifications. With remote monitoring, Wi-Fi connectivity, and mobile alerts, the FlexBOSS21 combines efficiency, scalability, and cutting-edge technology to power modern energy systems with confidence.

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

$5,059.00$4,199.00
SKU# INV027

Choose Your Inverter Option*

EG4 12kPV EG4 18kPV EG4 FlexBOSS18 EG4 FlexBOSS21

Choose Your Battery Option*

BigBattery ETHOS EG4 280Ah All Weather EG4 280Ah Indoor EG4 314Ah Indoor None

Choose Your Inverter Quantity*

Standard

Standard

Large

Large

3 Phase

3 Phase

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EG4 6000XP EG4 12000XP VICTRON MP II 3000 VICTRON MP II 5000

Choose Your Battery Option*

BigBattery NEXUS BigBattery ETHOS BigBattery HUSKY2 INV EG4 280Ah All Weather EG4 280Ah Indoor
SKU: INV027 Categories: ,

Compatible Accessories & Additional Add-ons

EG4 FlexBoss21 Inverter - Simply scalable
UL1741 Certified
Power stays on in storm and rain - EG4 FlexBoss21 Inverter
Power endures snow - EG4 FlexBoss21 Inverter
GridBoss - EG4 FlexBoss21 Inverter
EG4 lineup

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Inverter Downloads

SKU#:INV027
Spec Sheet:DownloadDOWNLOAD
User Manual:DownloadDOWNLOAD
UL1741 Certificate:DownloadDOWNLOAD
CEC Listing- EG4 FlexBoss21:Go to linkGO TO LINK

Inverter Specifications

Nominal AC Voltage:120/240VAC | 120/208VAC (L1/L2/N required)
Frequency:60 Hz (Default) | 50 Hz
Max. AC Current:50A @ 240V | 57.7A @ 208V
Max. AC Input Power:12000W
Max. AC Bypass:90A
Operating Voltage Range:180 – 270VAC
Output Voltage:120/240VAC | 120/208VAC (L1/L2/N required)
Max. Output Current:66.7A
Output Frequency:60 Hz (Default) | 50 Hz
Nominal Output Power (without PV):12000W @ 240V | 12000W @ 208V
Nominal Output Power (with PV):16000W @ 240V | 13800kW @ 208V
Power Factor:0.99 (Full Load)
Reactive Power Adjustment Range:-0.8 – 0.8 Leading Adjustable
Total Harmonic Distortion:<5% (Full Load)
Transfer Time:20ms (Default) | 10ms (Configurable) | 20ms (Parallel)
Rated Output Current:50A @ 240V | 57.7A @ 208V
Nominal Output Voltage:120/240VAC | 120/208VAC
Rated Output Power:12000W @ 240VAC | 12000W @ 208VAC
Peak Power:24000W (0.5 sec) | 18000W (1 sec)
15000W (6 min) | 13200W (12 min)
Operating Frequency:60 Hz (Default) | 50 Hz
Total Harmonic Distortion Voltage:<5%
Transfer Time:20ms (Default) | 10ms (Configurable) | 20ms (Parallel)
No. of MPPTs:3
Inputs per MPPT:2 (MPPT 1) | 2 (MPPT 2) | 1 (MPPT 3)
Max. Usable Input Current:26A (MPPT 1) | 26A (MPPT 2) | 15A (MPPT 3)
Max. Short Circuit Input Current:31A (MPPT 1) | 31A (MPPT 2) | 19A (MPPT 3)
DC Input Voltage Range:100 – 600VDC
Unit Start-Up Voltage:100VDC
MPPT Operating Voltage Range:120 – 440VDC
Nominal MPPT Voltage:360VDC
Max. Utilized PV Array Power:21000W
Max. Recommended PV Input:25000W
Max. Efficiency:97% (PV to Grid) | 94.5% (PV to Battery) | 94% (Battery to Grid)
Idle Consumption:<65W
Nominal Voltage:48VDC
Voltage Range:40 – 60VDC
Max. Charge / Discharge Power:12000W
Recommended Battery Capacity per Inverter:>300Ah
Operating / Storage Temperature Range:-13ºF – 140ºF (-25ºC – 60ºC)
Operating Altitude:<6,561 ft (2000 m)
Relative Humidity:0 – 100%
Typical Noise Emission:<50dB @ 3 ft
Design Topology:High-Frequency / Transformerless
Protection Rating:IP65 / NEMA 4X
Communications:RS485 / CANBus / WiFi
Max. Parallel Connections:16
Weight:88 lbs (40 kg)
Depth:11.3 in (287 mm)
Width:22.3 in (567 mm)
Height:30.5 in (775 mm)

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10-Year EG4 Manufacturer Warranty

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