Product Description

This kit pairs the EG4 FlexBOSS18 hybrid inverter — up to 18 kW of PV input and 13 kW of continuous split-phase AC output per EG4 — with the EG4 WallMount 314Ah All-Weather battery, an IP67-rated 16 kWh unit built for indoor or outdoor mounting. Configure one to three batteries for 16, 32, or 48 kWh of storage, all communicating in closed-loop within a single-manufacturer system. OffGrid Horizon is a family-owned authorized EG4 dealer, and every kit ships with full manufacturer warranty support.

Who This Is For

Homeowners who want one matched, single-brand energy storage system for backup power, solar self-consumption, or off-grid living — with batteries that can mount outdoors beside the inverter. If your loads are typical residential (well pump, refrigeration, HVAC in reasonable combinations), the FlexBOSS18's 13 kW output covers most homes; households with heavier simultaneous 240V loads should look at the FlexBOSS21 version of this kit.

Key Features

  • Up to 18 kW of PV input (600VDC max, up to 4 strings per EG4) with 13 kW continuous split-phase 120/240V output
  • 10 kW continuous output from battery alone per EG4 — the figure that matters at night and during outages
  • IP67 all-weather batteries — 16 kWh per unit, wall- or floor-mounted, indoor or outdoor
  • Closed-loop communication between inverter and batteries over CAN/RS485, with Auto-ID addressing as you add units
  • 10,000-cycle battery rating at 80% depth of discharge per EG4
  • Grid-tied, backup, and off-grid operating modes with app-based remote monitoring
  • NEMA 4X inverter enclosure per EG4, suitable for outdoor installation alongside the batteries

Why EG4

EG4 Electronics is a Texas-based manufacturer that builds both halves of this system, publishes full spec sheets and test data, and backs the inverter and batteries with 10-year warranties. One engineering team, one support line, one communication protocol — no cross-brand compatibility guesswork.

What's In the Kit

  • 1 x EG4 FlexBOSS18 hybrid inverter — split-phase 120/240V, UL3141 and UL1741 certified per EG4
  • 1, 2, or 3 x EG4 WallMount 314Ah All-Weather batteries (16 kWh each) — the listed configuration includes one battery; select your capacity from the product options

Solar panels, racking, and array wiring are site-specific and sold separately. The system also operates as battery backup without solar.

Specifications

Inverter EG4 FlexBOSS18 hybrid, split-phase 120/240V
PV input Up to 18 kW (STC), 600VDC max, up to 4 strings, per EG4
AC output 13 kW continuous (grid-tied with solar contribution); 10 kW from battery alone, per EG4
Inverter certifications UL3141; UL1741, per EG4
Inverter enclosure NEMA 4X, per EG4
Battery EG4 WallMount 314Ah All-Weather, 51.2V, 16 kWh nominal per unit
Capacity options 16 / 32 / 48 kWh (1, 2, or 3 batteries)
Battery output 200A max continuous discharge per unit, per EG4
Battery enclosure IP67 — indoor or outdoor mounting
Battery certifications UL1973; UL9540A, per EG4
Battery cycle life 10,000 cycles at 80% DoD, per EG4
Battery dimensions / weight 34.6 x 21.7 x 9.3 in / 309 lb per unit
Communication Closed-loop CAN/RS485; app-based remote monitoring
Warranty Inverter 10 years; batteries 10 years or 10,000 cycles, per EG4
Base SKU K0286

Grid-Tied, Backup, or Off-Grid

Grid-tied: the FlexBOSS18 manages solar production, battery charging, and export under UL1741 interconnection rules — your utility and AHJ govern export permissions. Backup: when the grid drops, the system transfers to battery power; one battery (16 kWh) carries essential circuits overnight, while 32 or 48 kWh supports whole-home coverage or multi-day outages. Off-grid: the same hardware runs fully off-grid, sized by your daily load and sun hours. For whole-home microgrid control — AC coupling, smart load management, and generator integration per EG4 — add the EG4 GridBoss 200A MID.

Inverter Compatibility

The batteries in this kit run closed-loop with the included EG4 FlexBOSS18 hybrid inverter, so state-of-charge and charge parameters stay coordinated out of the box. Want more output headroom? The FlexBOSS21 version of this kit uses the same batteries. Individual WallMount 314Ah All-Weather batteries are available separately when you are ready to expand.

Installation

Installation must be performed by a licensed electrician — the inverter interconnects with your main panel and, in grid-tied modes, with the utility, and energy storage installations require local permits and inspection. Each battery weighs 309 lb and mounts to the wall or floor per EG4's manual; anchor wall-mounted units into structural framing and plan for lifting equipment. Follow EG4's installation manuals for clearances, torque values, and conductor sizing.

Warranty & Support

Per EG4, the FlexBOSS18 carries a 10-year warranty and each WallMount battery is covered for 10 years or 10,000 cycles, whichever comes first. Register your equipment with EG4 after purchase and keep your OffGrid Horizon invoice — as an authorized dealer, our records document your coverage. For warranty or configuration help, call us at (302) 496-3554.

Shipping

Kits ship by LTL freight on pallets within the United States, curbside with a liftgate. Count every piece against the packing list and inspect for damage before signing the delivery receipt — note any issues with the driver to preserve your freight claim.

Frequently Asked Questions

How many batteries are included?

The base configuration includes one 16 kWh battery. Select the 2-battery (32 kWh) or 3-battery (48 kWh) option from the product configuration menu before checkout.

Can I add batteries later?

Yes — per EG4 the WallMount 314Ah parallels up to 32 units, and Auto-ID addressing configures new batteries automatically. Most owners start with one or two and expand.

Are solar panels included?

No. Panels, racking, and array wiring are sized to your roof or ground mount and sold separately. The kit operates as grid-charged battery backup without any solar attached.

How much power do I get during an outage?

Per EG4, the FlexBOSS18 delivers 10 kW continuous from battery alone. One battery supports about 10.2 kW of discharge (200A), so even the single-battery configuration can feed the inverter's full battery-mode output.

Do I need the GridBoss?

Not for a basic partial-home backup or off-grid build. Per EG4, adding GridBoss brings AC coupling, smart load control, and generator integration for whole-home microgrid setups.

Should I pick the All-Weather or Indoor kit?

Choose All-Weather (this kit) when batteries mount outside or in weather-exposed spaces. If they will live in a garage or basement, the Indoor kit uses a lighter battery that per EG4 forms a UL9540 system with the FlexBOSS18.

Sizing between 16, 32, and 48 kWh — or between the FlexBOSS18 and 21? Call OffGrid Horizon at (302) 496-3554 and our family-owned team will walk your loads with you before you order.

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