EG4 EG4FLEXBOSS18 13kW Hybrid Inverter/Charger

EG4 FlexBOSS18 — 13kW Split-Phase All-in-One Hybrid Inverter | NEMA 4X | 18kW Solar Input

The EG4 FlexBOSS18 is a versatile, grid-interactive hybrid inverter built for homeowners and installers who demand professional-grade performance, advanced grid compliance, and the durability to handle harsh outdoor environments. Delivering 13,000W of continuous AC output when solar is present, 18kW of solar input capacity, a built-in 90A transfer switch, full rapid shutdown compliance, and a NEMA 4X-rated enclosure that handles coastal salt spray, heavy rain, and high humidity — the FlexBOSS18 is engineered for installations where other inverters simply aren't rated to go. Pair it with the optional EG4 GridBOSS for a complete, fully integrated grid management system that eliminates external breakers, transfer switches, and additional hardware.

13kW Output with Solar, 10kW from Battery — Whole-Home Hybrid Power

The FlexBOSS18 delivers 10,000W of continuous AC output running from battery alone, boosting to 13,000W of combined output when solar production is available — intelligently blending grid, solar, and battery power to supply your home's full load without waste or manual switching. This solar-assisted output boost means your battery bank is never working harder than it needs to, extending both daily runtime and long-term battery cycle life.

18kW of Solar Input — Dual MPPT at 600VDC Max

Two independent MPPT charge controllers accept up to 18,000W of combined PV input at up to 600VDC maximum — the full ceiling allowed under the National Electrical Code. Higher maximum input voltage means longer, more efficient string designs, fewer parallel runs, lighter wiring, and lower balance-of-system costs compared to inverters limited to 480V or 500V. Each MPPT channel handles up to 26A of input current, supporting a wide range of panel configurations for both rooftop and ground-mount arrays.

NEMA 4X Enclosure — Built for Coastal, Outdoor, and Harsh Environments

The FlexBOSS18's NEMA 4X-rated enclosure is one of its most significant differentiators. Where most hybrid inverters are rated only to IP65 or NEMA 3R, NEMA 4X goes further — providing full protection against windblown dust, rain, splashing water, hose-directed water, and corrosive salt spray found in coastal and marine environments. This makes the FlexBOSS18 one of the few residential hybrid inverters genuinely rated for direct outdoor installation in Florida, Hawaii, and other coastal climates without additional weatherproofing enclosures or mitigation measures.

Built-In Rapid Shutdown and RSD Transmitter — NEC 690.12 Ready

The FlexBOSS18 ships with complete Rapid Shutdown capability and an integrated RSD transmitter, meeting NEC 690.12 requirements for roof-mounted PV systems without additional hardware. This built-in compliance reduces the component count, simplifies the permit package, and eliminates a common source of field installation errors — all while keeping the final installation code-compliant for both AHJ inspections and utility interconnection.

90A Grid Bypass Transfer Switch — Built In

A fully integrated 90A transfer switch handles automatic grid-to-battery and battery-to-grid transitions without external switching hardware. When the grid is available, power flows seamlessly through the inverter at full amperage. When the grid drops, the FlexBOSS18 switches to battery and solar backup automatically — with no manual intervention and no separate ATS to purchase, wire, or permit.

GridBOSS Integration — Eliminate Breakers, Transfer Switches, and Extra Hardware

The FlexBOSS18 is purpose-built to pair with the EG4 GridBOSS MID, EG4's dedicated grid management module. When combined with the GridBOSS, the system delivers a fully integrated energy management platform that eliminates the need for external breakers, transfer switches, and additional distribution hardware — reducing both material costs and installation labor significantly. The GridBOSS unlocks additional capabilities including AC coupling with existing grid-tie inverters, dedicated generator management, smart load control, and advanced grid interaction modes — all managed through a single unified interface.

Multiple Operating Modes — Grid-Tie, Off-Grid, Zero Export, TOU, and More

The FlexBOSS18 supports the full spectrum of operating modes required for modern residential energy management. In self-consumption mode it prioritizes solar and battery over grid power. In zero export mode it prevents any energy from flowing back to the grid — satisfying utility interconnection requirements in markets that prohibit net metering. Time-of-Use (TOU) programming charges batteries during off-peak rate hours and discharges during expensive peak periods. Force discharge mode dispatches stored energy on demand. In fully off-grid mode, it operates independently from the grid using solar and battery exclusively. All modes are accessible and adjustable remotely through EG4's monitoring software.

AUX Terminals with Generator Auto-Start

Dedicated AUX terminals support automatic generator start and stop based on battery state-of-charge thresholds — no additional relay or controller required. When battery reserves fall below your configured minimum, the FlexBOSS18 signals the generator to start, charges the battery, and shuts the generator down once the target SOC is reached. Fully automated, hands-free generator management out of the box.

208A Battery Charger — Fast and Flexible Battery Charging

The FlexBOSS18's integrated 208A battery charger replenishes 48V battery banks quickly from solar, grid, or generator sources. Closed-loop RS485 and CANBus BMS communication enables direct interoperability with EG4's own battery line as well as a wide range of third-party lithium battery brands — providing precise, chemistry-aware charging that maximizes battery performance and longevity. Open-loop mode supports any 48V battery including lead-acid, AGM, and gel.

Advanced Grid Certifications — California, Hawaii, and IEEE Compliant

The FlexBOSS18 carries one of the most comprehensive certification packages available for a residential hybrid inverter in the United States, including UL 1741 SA and SB, California Rule 21 Phase I/II/III, Hawaii Rule 14H, IEEE 1547-2018 and 1547.1-2020, and CSA C22.2#330:2017. When paired with EG4 WallMount batteries, the system achieves UL 9540 certification as a complete energy storage system. This certification breadth means the FlexBOSS18 is permit-ready and utility-interconnection-compliant in virtually every U.S. market — including the most stringent utility territories in California and Hawaii.

Scalable to 130kW — Up to 10 Units in Parallel

Up to 10 FlexBOSS18 units can be connected in parallel for a combined continuous output of 130kW — making this platform a viable solution for large residential estates, light commercial facilities, and multi-unit properties that have outgrown single-inverter capacity, all while keeping the same firmware, monitoring platform, and installation ecosystem.

60W Idle Consumption and Remote Monitoring

The FlexBOSS18's 60W idle power draw keeps standby losses low around the clock. Remote monitoring and configuration are available through EG4's cloud-based software platform, accessible from any browser or mobile device. Adjust operating modes, review production and consumption data, and update settings without a site visit.

10-Year Warranty

The FlexBOSS18 is backed by a 10-year full parts and product replacement warranty — one of the longest standard warranties available in its class — reflecting EG4's confidence in the platform's long-term durability and reliability.