The BigBattery ETHOS™ + EG4 FlexBOSS21 ESS System is a complete, next-generation energy solution designed for both on-grid and off-grid applications. Combining the scalable ETHOS 48V lithium battery system with the powerful FlexBOSS21 hybrid inverter, this system delivers advanced, efficient, and intelligent energy management in one integrated package.
Expandable up to 80+ kWh, the ETHOS battery grows with your energy needs – while the FlexBOSS21 delivers 12kW output and up to 21,000W PV input with 3 MPPTs for maximum solar optimization. Integrated with the GridBOSS MID gateway, the system enables advanced energy control, including load management, AC coupling, and generator integration.
Designed with UL 9540 certified configurations, advanced battery management, and U.S.-engineered components, this system ensures safe, maintenance-free performance with seamless closed-loop communication and real-time monitoring.
- Ships From: Texas, USA
- Warranty: 12 Years (Battery), 10 Years (Inverter)
- Support: Lifetime USA-Based Tech Support
CompatibilityIntegrated & Optimized System - ETHOS Battery System + EG4 FlexBOSS21 Hybrid Inverter
Expandable & Flexible - Scalable ETHOS battery capacity up to 80+ kWh
- Compatible with additional ETHOS modules for future expansion
- Supports grid-tied, hybrid, and off-grid installations
Key Features - Complete ESS Solution – Battery + inverter system designed to work seamlessly together
- 21,000W PV Input – High solar capacity with 3 MPPTs for maximum efficiency
- 12kW Output Power – Supports residential and light commercial loads
- 120/240V Split-Phase Output – Reliable power for whole-home applications
- LiFePO? Battery Chemistry – Safe, stable lithium technology with long lifespan
- 6,000+ Cycle Life – Built for years of daily use and long-term savings
- Closed-Loop Communication – Optimized coordination between battery and inverter
- GridBOSS Integration – Advanced load management, AC coupling, and generator support
- Advanced Safety Protections – Includes rapid shutdown, ground fault, and arc fault protection
- Modular Expansion – Easily scale storage capacity as energy needs grow
- Remote Monitoring & Alerts – Wi-Fi connectivity with real-time system tracking
- Maintenance-Free Operation – No routine servicing required
A powerful, future-ready energy storage system built for flexibility, performance, and long-term independence – backed by advanced controls, safety, and U.S.-based support.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 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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