FlexBOSS21 Hybrid Inverter
The bigger sibling of the FlexBOSS18. One box runs solar, a battery bank, and the grid, with 16kW continuous output, 21kW of PV input, and 12kW on battery alone when the grid is down. Three MPPTs give you more room to split a big array, and it has the muscle to start a 5-ton AC unit. Pair it with the EG4 GridBOSS for whole-home backup.
Only 3 left in stock, order soon.
5.036 Google reviews- AC output
- 16 kW
- Max DC input
- 21000 W
- MPPT channels
- 3
- Max MPPT voltage
- 550 V
- MPPT current
- 26 A
- MPPTs
- 3 (26 A / 26 A / 15 A)
One box. Solar, battery, and grid.
The EG4 FlexBOSS21 is a 48V split-phase hybrid inverter that runs solar, a battery bank, and the grid through a single unit. It puts out 16kW continuous with solar behind it, takes up to 21kW of PV in across three MPPTs, and still delivers 12kW on battery alone when the grid goes down. It is the bigger sibling of the FlexBOSS18 and has the headroom to start a 5-ton AC unit.
16kW hybrid output
16kW continuous with PV behind it, and 12kW straight off the battery when the grid is out.
21kW of solar input
Room for a large array across three MPPT trackers, so the system keeps producing as the sun moves and shade shifts.
Pairs with GridBOSS
Add the EG4 GridBOSS MID and a whole-home backup system comes together without a stack of extra transfer switches and breakers.
Three MPPT trackers
Split a big array three ways. Face strings in different directions and the FlexBOSS21 still pulls the most out of each one.
UL1741 certified
Meets the safety standard utilities and inspectors look for, whether the system is grid-tied or off-grid.
Parallel to 10 units
Start with one and stack up to ten as the loads grow. The system scales with the house, not the other way around.
The FlexBOSS21 is the inverter we reach for when one house needs more output per unit than the FlexBOSS18 gives. It handles whole-home backup, net-metered systems, grid-tied builds with battery storage, and off-grid setups that run heavy loads. If 13kW is enough and the budget is tighter, the FlexBOSS18 covers most jobs.
Spec sheets, manuals, and white papers.
Spec sheets
Manuals & guides
Wiring diagrams
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