EG4 GridBOSS + FlexBOSS-21 - 14.3kWh Indoor Battery & 12kW Hybrid Inverter Battery Package

Power your off-grid or grid-tied system with confidence using the EG4 GridBOSS + FlexBOSS-21 Kit, a complete indoor-rated energy storage solution built for performance, safety, and expandability. This system includes the EG4 FlexBOSS-21 (V1.1) Hybrid Inverter, a 14.3kWh WallMount Indoor Battery, the EG4 GridBOSS Microgrid Interconnection Device (MID V3.1), and a custom Indoor Buildable Conduit Box. The matched components streamline CSA-compliant installation, maximize solar harvest, and give you closed-loop control through the EG4 app.

With up to 21kW PV input, intelligent smart load control, and 600V DC solar support, the FlexBOSS-21 is ideal for both residential and light commercial energy setups. Paired with the indoor-rated 14.3kWh battery and GridBOSS MID V3.1, this bundle delivers full system control, monitoring, and protection in a clean wall-mounted form factor.

Package Includes

1 × EG4 FlexBOSS-21 Hybrid Inverter (V1.1), 48V split-phase, 12kW output, up to 21kW PV input

1 × EG4 14.3kWh Indoor WallMount Battery, 280Ah, 51.2V, built-in BMS and touch display

1 × EG4 GridBOSS Microgrid Interconnection Device (MID V3.1), 200A, breakers sold separately 

1 × EG4 Indoor Buildable Conduit Box, streamlined cable protection and code-friendly spacing

Key Features

• Massively scalable solar capacity with up to 21kW PV input and three MPPTs
• Smart load management, generator integration, and multi-mode inverter control
• Remote monitoring and alerts via the EG4 app and web portal 
• Parallel up to 16 FlexBOSS-21 units for high continuous output potential
• Safety-focused design with rapid shutdown support, arc-fault detection, and ground fault protection
• Wall-mounted 14.3kWh lithium iron phosphate battery with integrated display and self-heating support
• Internal 600A busbars for parallel installations without external wiring blocks
• Clean cable routing with the indoor buildable conduit box for CSA and NEC friendly installs
• GridBOSS MID V3.1 adds complete breaker customization because breakers are now sold separately 
• Compatible breaker series include Eaton BR Series and BSB B3S Series (available as the standard GridBOSS breaker kit or individually) 
• Aluminum wire is permitted for external connections, and copper wire must still be used inside the unit to maintain UL certification 

Canadian Installation Notes

To meet CSA requirements, the GridBOSS is not service-entrance rated. A 100A or 200A disconnect is required between the electrical meter and the GridBOSS. 

GridBOSS MID V3.1 ships without breakers. Breakers must be selected separately to match your inverter, generator input, and smart-load configuration. 

To maintain UL certification inside the GridBOSS, copper wire must be used inside the unit. Aluminum wire is permitted for external connections. 

Specs

FlexBOSS-21 Inverter

• Output Power: 12kW continuous (up to 16kW with PV input), 24kW surge
• PV Input: 21kW, 600V DC max
• Voltage: 120/240V split-phase
• Dimensions: 29.5 in × 20.5 in × 11.2 in
• Weight: 88 lb
• Warranty: 10 years

WallMount Indoor Battery

• Energy: 14.3kWh
• Voltage: 51.2V
• Capacity: 280Ah
• Cycle Life: 8000+ cycles at 80% DoD
• Weight: 282 lb
• Communication: RS485 / CAN
• Certifications: UL 1973, UL 9540A
• Integrated display, self-heating, emergency shutoff compatible

GridBOSS MID (V3.1) 

• Voltage: 120/240 VAC 
• Max Current: 200 A 
• Hybrid Ports: 3 (up to 90 A each) 
• Smart Ports: 4 (up to 125 A each, 60A to 125A range) 
• Flexible breaker positions: 1 × generator (up to 125A), 3 × hybrid inverters (up to 90A each), 4 × smart ports (60A to 125A range) 
• Operating Temp: -40°F to 140°F 
• Warranty: 10 years 
• Certifications: UL Certified 
• Main Breaker Compatibility: Eaton 200A CSR25K 
• Notes: Ships without breakers. Supported breaker models include Eaton BR Series and BSB B3S Series.