Product Description

The EG4 GridBOSS is a 200A microgrid interconnection device (MID) that sits at the service entrance and manages the connections between the utility grid, your EG4 hybrid inverters, a generator, and your home's loads. Per EG4, it combines a 200A service entrance with a 22kAIC main breaker, whole-home backup switching in roughly 25 ms, a 125A generator input, four smart-load ports, and three hybrid inverter ports — replacing the pile of separate transfer switches, load-shed relays, and generator interlocks a whole-home backup system would otherwise need.

Who This Is For

Anyone installing an EG4 FlexBOSS18, FlexBOSS21, 18kPV, or 12kPV system who wants the whole house backed up — not just a critical-loads subpanel. It consolidates the service-entrance switching and load management into one engineered, listed device, which generally means cleaner wiring and a simpler inspection than field-built switchgear.

Key Features

  • 200A whole-home backup switching — 120/240VAC service entrance with a 22kAIC main breaker; internal bus rated 350A, software-limited to 200A per EG4
  • Automatic transfer in ~25 ms per EG4 when the grid drops, so the house rides through on inverter and battery power
  • Four smart-load ports (125A, 80A, 60A, 60A per EG4) that shed lower-priority circuits to stretch battery runtime during an outage
  • 125A generator input for standby or portable generators during extended outages
  • Three hybrid inverter ports supporting the EG4 12kPV, 18kPV, FlexBOSS18, and FlexBOSS21 per EG4, with AC-coupling support for existing solar per EG4
  • NEMA 3R outdoor-rated enclosure with a -40 to 113 °F operating range — at 55 lb, light enough for a straightforward service-wall install
  • UL 1741, UL 67, UL 869A, and UL 916 listings per EG4's published spec sheet

Why EG4

EG4 Electronics is a US-based manufacturer with published spec sheets, manuals, and wiring diagrams and US-based technical support. The GridBOSS is purpose-built for EG4's own hybrid inverters, so the switching, load management, and monitoring behave as one documented system in the EG4 Connect platform rather than a mix of third-party components.

Specifications

Specifications below are per EG4's published GridBOSS spec sheet.

Type Microgrid interconnection device (MID)
Service rating 200A service entrance; 22kAIC main breaker
Internal bus 350A rated, software-limited to 200A
Grid input 120/240VAC (L1/L2/N), 60 Hz, 200A max
Backup output 120/240VAC, 60 Hz, 200A
Generator input 120/240VAC, 60 Hz, 125A max
Smart-load ports 4 ports: 125A / 80A / 60A / 60A, with load shedding
Hybrid inverter ports 3 ports; supports EG4 12kPV, 18kPV, FlexBOSS18, FlexBOSS21
Transfer time ~25 ms
Certifications UL 1741; UL 67; UL 869A; UL 916; CSA C22.2 #29 & #107.1; FCC Part 15 Class B
Enclosure / environment NEMA 3R; -40 to 113 °F
Dimensions / weight 31.5 x 19.7 x 7 in; 55 lb
Communications RS485, Wi-Fi, CAN; EG4 Connect monitoring
Warranty 10-year standard per EG4 (registration required within first year)
SKU INV033

What a Microgrid Interconnection Device Does

When a grid-tied battery system loses utility power, code requires it to disconnect from the grid before it can keep energizing your home — otherwise it would backfeed the utility's lines. A MID is the device that performs that separation at the service level: it isolates the house from the grid, lets the inverters form their own "microgrid" to power the whole 200A service, and re-synchronizes to the utility when power returns. The GridBOSS adds load intelligence on top — shedding its smart-load circuits (for example, HVAC, water heater, or EV charger) in priority order so the battery carries the essentials longer — and brings a 125A generator input into the same enclosure for extended outages. Without a MID, a hybrid inverter can typically back up only a dedicated subpanel; with one, the entire service is switched.

Battery Compatibility

The GridBOSS does not connect to batteries directly — storage lives behind the hybrid inverters it manages, such as the FlexBOSS18 or FlexBOSS21 paired with EG4 WallMount 48V batteries in closed-loop communication. The runtime your whole-home backup actually delivers is set by that battery bank, so size it to your daily loads.

Installation

The GridBOSS installs at the service entrance — this is licensed-electrician work involving the utility service, and it requires local permits and, for grid-interactive systems, utility interconnection approval. The NEMA 3R enclosure is rated for outdoor mounting next to the meter. Plan the smart-load circuits with your electrician up front: which circuits shed first is a design decision, not an afterthought.

Warranty & Support

Per EG4, the GridBOSS carries a 10-year standard warranty; registration within the first year (or proof of purchase from an authorized distributor) is required. OffGrid Horizon is a family-owned authorized EG4 dealer — call (302) 496-3554 and we will help with system design questions or warranty claims.

Shipping

Ships within the contiguous United States. At 55 lb, the GridBOSS typically ships by ground carrier or palletized with an inverter order. Inspect the carton on arrival and note any damage with the carrier before signing; contact us immediately if anything is wrong.

Frequently Asked Questions

Do I need a GridBOSS for a FlexBOSS system?

Not strictly — a FlexBOSS inverter can back up a critical-loads panel on its own. The GridBOSS is what upgrades the system to automatic whole-home backup at the 200A service level, with smart-load shedding and generator integration.

Which inverters does it work with?

Per EG4, the hybrid ports support the EG4 12kPV, 18kPV, FlexBOSS18, and FlexBOSS21 — up to three inverter connections.

Does it work with a generator?

Yes — a dedicated 125A generator input is built in per EG4, so a standby or portable generator can support the system during extended outages.

What are the smart-load ports for?

Four ports (125A, 80A, 60A, 60A per EG4) for circuits you are willing to shed during an outage — the GridBOSS drops them in priority order to keep essential loads running longer on battery.

Can it AC-couple my existing solar?

Per EG4, the GridBOSS supports AC coupling, letting an existing grid-tie array feed the system. Configuration depends on your equipment — call us to confirm your setup.

Does it include batteries or an inverter?

No — the GridBOSS is the interconnection and switching device. Pair it with one to three EG4 hybrid inverters and a 48V battery bank.

Is utility approval required?

Yes, for grid-interactive systems — the GridBOSS sits at the service entrance, so installation involves local permitting and your utility's interconnection process. Export of solar power remains subject to utility approval.

Designing whole-home backup? Call OffGrid Horizon at (302) 496-3554 — family-owned, authorized EG4 dealer — and we will map out the GridBOSS, inverters, and batteries for your service.

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