Battery Selected
2× 48V ETHOS
Total Capacity
10.24 kWh
Inverter Selected
1× EG4 FlexBOSS21
Input / Output
21 kW / 16 kW
Everything You Need, Included
Your complete 48V system
2× BigBattery ETHOS
1× ETHOS Control Box
1× EG4 FlexBOSS21 Hybrid Solar Inverter
1× 10kWh Ethos Controller to Battery Power Cable 31.5\\\\\\\" inch (800mm)- U.S. Support
- LiFePO₄ Safety
BigBattery 48V ETHOS Battery + EG4 FlexBOSS21 ESS | 10.24–46.1kWh | UL9540 | (21kW–63kW PV) | Grid-Tied Home System
SKU# K0241
Choose Your Inverter Option*
Converts battery power to usable electricity.
Choose Your Battery Option*
Stores your energy for when you need it.
Choose Your Inverter Option*
Converts battery power to usable electricity.
BigBattery APEX-10K Off-Grid Inverter
BigBattery APEX-6.5K Off-Grid Inverter
EG4 6000XP (8kPV) OFF-GRID INVERTER
EG4 12000XP V2 OFF-GRID INVERTER
Victron MultiPlus-II 48/5000/70-95 120V
Victron MultiPlus-II 48/3000/35-50 120V (UL 1741)
EG4 18kPV All-in-One Hybrid Solar Inverter
EG4 FlexBOSS18 Hybrid Solar Inverter
EG4 FlexBOSS21 Hybrid Solar Inverter
NoneI already have an inverter
BigBattery APEX-6.5K Off-Grid InverterEG4 6000XP (8kPV) OFF-GRID INVERTEREG4 12000XP V2 OFF-GRID INVERTERVictron MultiPlus-II 48/5000/70-95 120VVictron MultiPlus-II 48/3000/35-50 120V (UL 1741)EG4 18kPV All-in-One Hybrid Solar InverterEG4 FlexBOSS18 Hybrid Solar InverterEG4 FlexBOSS21 Hybrid Solar InverterNoneI already have an inverter Choose Your Battery Option*
Stores your energy for when you need it.
Choose Your ESS Configuration*
Compare the available system sizes and choose the configuration that fits your power needs.
1x Inverter
Standard
Great for small homes or basic backup needs.
2x Inverter
Large
Ideal for larger homes or higher energy demands.
3x Inverter
3 Phase
For commercial, agricultural or high-load applications.
$6,379.99
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Documents & Certifications
Battery
Inverter
About this item
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
Compatibility
Integrated & 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 SolutionBattery + inverter system designed to work seamlessly together
- 21,000W PV InputHigh solar capacity with 3 MPPTs for maximum efficiency
- 12kW Output PowerSupports residential and light commercial loads
- 120/240V Split-Phase OutputReliable power for whole-home applications
- LiFePO₄ Battery ChemistrySafe, stable lithium technology with long lifespan
- 6,000+ Cycle LifeBuilt for years of daily use and long-term savings
- Closed-Loop CommunicationOptimized coordination between battery and inverter
- GridBOSS IntegrationAdvanced load management, AC coupling, and generator support
- Advanced Safety ProtectionsIncludes rapid shutdown, ground fault, and arc fault protection
- Modular ExpansionEasily scale storage capacity as energy needs grow
- Remote Monitoring & AlertsWi-Fi connectivity with real-time system tracking
- Maintenance-Free OperationNo 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.
Real Installations From Customers Like You!
Enter your build here to show off your build and receive a gift-box from us! Selected photos will be featured on our website and product pages.
Battery Downloads
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#:INV027
Spec Sheet:
DOWNLOAD
DOWNLOADUser Manual:DOWNLOAD
DOWNLOADUL1741 Certificate:DOWNLOAD
DOWNLOADCEC Listing- EG4 FlexBoss21:
GO TO LINK
GO TO LINKInverter 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)
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)
Real Installations From Customers Like You!
Enter your build here to show off your build and receive a gift-box from us! Selected photos will be featured on our website and product pages.
Battery Downloads
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#:INV027
Spec Sheet:DOWNLOAD
DOWNLOADUser Manual:DOWNLOAD
DOWNLOADUL1741 Certificate:DOWNLOAD
DOWNLOADCEC Listing- EG4 FlexBoss21:GO TO LINK
GO TO LINKInverter 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)
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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BigBattery 48V ETHOS Battery + EG4 FlexBOSS21 ESS | 10.24–46.1kWh | UL9540 | (21kW–63kW PV) | Grid-Tied Home System
Price range: $6,379.99 through $34,450.97
