About the EG4 GridBOSS Microgrid Interconnect Device
A solar and battery system with whole-home backup usually ends up with a main disconnect, a transfer switch, a generator transfer, an AC-coupling combiner and a few contactors for big loads. The GridBOSS rolls all of that into one microgrid interconnect device (MID), the gateway between your utility meter and up to three EG4 hybrid inverters. Grid, solar, batteries, generator and loads all land in one cabinet, and one controller manages them together.
Pair it with up to three EG4 FlexBOSS21 inverters and you have a whole-home system on a single 200A service. One customer replaced his separate service disconnect with a GridBOSS fed straight from the meter, then put an EV charger on one smart port and his existing microinverters on another.
200A Service Entrance Rating With the Eaton CSR Main Breaker
Add a 200A main breaker inside the cabinet and the GridBOSS can serve as your service entrance, fed directly from the utility meter at 22kAIC. That rating and the UL 869A listing apply with the Eaton CSR2200N main breaker, which is sold separately. Without the main, the grid conductors land on lugs that take 4 AWG to 250 kcmil copper or aluminum.
Automatic Transfer Switch for Whole-Home Backup
The GridBOSS has separate 200A connections for backup and non-backup loads, so you can back up the entire panel or split off loads you only want on grid power. When the grid drops, the transfer switch isolates the house from the utility in about 25 milliseconds and the inverters carry the backup side.
A 200A manual bypass with a mechanical interlock is built in. Flip it and grid power feeds the backup loads directly, so you can service the inverters while the house stays powered.
GridBOSS Smart Ports for AC Coupling, EV Chargers and Smart Loads
Four programmable smart ports, rated 125A, 80A, 60A and 60A, take the jobs that used to need extra hardware. In Smart Load mode, a port switches a circuit on or off by time of day, battery state of charge or voltage, or surplus solar, so an EV charger, water heater or pool pump runs when the power is there.
In AC Couple mode, a port brings an existing grid-tied array, such as microinverters, into the system. EG4 requires those inverters to carry a UL 1741, UL 1741 SA or UL 1741 SB listing.
Generator Input With Two-Wire Auto Start
The generator gets its own port, separate from the smart ports, with breakers from 30A to 125A. A two-wire start contact fires the generator on battery state of charge, battery voltage or a remote command. A programmable warm-up of 30 seconds to 10 minutes lets it settle before it picks up the loads and charges the batteries.
GridBOSS Breakers: BSB or Eaton, Sized for Each Port
The v3.1 ships without port breakers, so you buy only the sizes your system uses. Each hybrid port takes a breaker matched to its inverter: 50A for the 12kPV, 70A for the 18kPV or FlexBOSS18, and 90A for the FlexBOSS21. The generator and smart ports take 30A to 125A depending on the port, and Eaton BR two-pole breakers cover every size.
This hardware accepts both BSB and Eaton two-pole breakers. Eaton breakers work with copper or aluminum wire, while BSB breakers take copper only. If you're not sure which sizes your build needs, our team is happy to help with sizing.
Installation, Rapid Shutdown and Monitoring
The NEMA 3R cabinet mounts indoors or out on a vertical, non-combustible wall such as brick or concrete, and it weighs 55 lb (25 kg), so plan on two people to hang it. Inverters can sit up to 260 ft (80 m) away on CAT5 or better communication cable.
A rapid shutdown switch on the side of the cabinet shuts the system down to meet NEC 690.12 and 706.15, and you can wire a remote initiator in line. The included Wi-Fi dongle connects the GridBOSS to EG4's monitoring platform.
EG4 calls for installation by qualified personnel following the NEC and local code, with utility approval before the system connects to the grid. The job is a service-level electrical install: landing the meter feed, setting the neutral-ground bond, running inverter and communication cables, and programming the ports.
