6x ETHOS + EG4 FLEXBOSS21 ESS Off-Grid System

Product Summary: The BigBattery ETHOS + EG4 FlexBOSS21 system pairs modular, UL-certified 48V lithium storage with a next-generation hybrid inverter for a complete, future-ready energy solution. ETHOS provides scalable capacity, intelligent management, and a 12-year warranty for long-lasting, maintenance-free energy independence, while FlexBOSS21delivers 12kW output and up to 21,000W of PV input with 3 MPPTs, 90A grid feed-through at 120/240VAC, and seamless integration with the EG4 GridBOSS MID gateway for smart load management, AC coupling, and generator support. With built-in rapid shutdown, ground fault and arc fault protection, plus Wi-Fi monitoring and mobile alerts, this combo offers safe, efficient, and highly flexible power for modern on-grid or off-grid residential and commercial systems. Items IncludedSKU 6xBigBattery ETHOS | 48V - 5.1kWh | UL1973 | Home Battery Backup LFPFETHS-48051-G1 1xETHOS Control BoxCNT060 1xEG4 FlexBOSS21 Hybrid Solar Inverter | 21kW PV / 16kW AC | Split-Phase | 4-MPPT | Scalable | Remote Wi-Fi MonitoringINV027 2xETHOS Stack to Stack Power Cable Pair (4.9 ft)CBL089 1xETHOS Stack to Stack Comm Cable (4.9 ft)CBL096 1xETHOS RACK BASECNT081 1xETHOS Battery Top Plate Cover — Side Panel Protection AccessoryCNT139 Battery Downloads SKU#:K0241, K0242, K0243, K0244, K0245, K0246, K0247, K0248, K0249, K0250, K0251 Spec Sheet:DOWNLOAD User Manual:DOWNLOAD UL9540 Certificate – BigBattery ETHOS + EG4 FlexBOSS21:DOWNLOAD UL9540A Certificate:DOWNLOAD UL1973 Certificate:DOWNLOAD UN38.3 Certificate:DOWNLOAD Safety Data Sheet:DOWNLOAD CEC Listing – BigBattery ETHOS + EG4 FlexBOSS21:GO TO LINK Battery Specifications GTIN-12 (U.P.C.):850061252005 System Voltage:48V Nominal Voltage:51.2V Chemistry:LiFePO4 kWh Capacity:10.24kWh Ah Capacity:200Ah Charging Voltage Range:55.6 – 57V Max Charge Voltage:57V Operating Voltage Range:48 – 57V Suggested Low Voltage Cutoff:48 – 50.8V BMS Cutoff Range:42 – 47V Cell Configuration:16S 2P Max Continuous Discharge Current:200A Max Continuous Power:10240W Max Discharge Peak Current:300A (Max 5 seconds) Max Charge Current:200A Charge Temperature Range:32°F – 113°F (0°C – 45°C) Discharge Temperature Range:-4°F – 140°F (-20°C – 60°C) Optimal Discharge Temperature Range:59°F – 95°F (15°C – 35°C) Storage Temperature Range (SoC >50%):-4°F – 113°F (-20°C – 45°C)(Max 6 months) Weight:273 lb (123.8 kg) Depth:6.7 in (170 mm) Width:26.5 in (674 mm) Height:43.3 in (1100 mm) Max Connections:Up to (16) parallel connections per control box Protection Rating:IP65 / NEMA 4X Communications:CANBus / RS485 Certifications:UL9540, UL9540A, UL1973, & UN38.3 Inverter Downloads SKU#:K0241, K0242, K0243, K0244, K0245, K0246, K0247, K0248, K0249, K0250, K0251 Spec Sheet:DOWNLOAD User Manual:DOWNLOAD UL1741 Certificate:DOWNLOAD CEC Listing – BigBattery ETHOS + EG4 FlexBOSS21:GO 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)