Product Description

The whole-home configuration of the NEXUS line: two or three BigBattery NEXUS 48V LiFePO4 batteries — 280Ah and 14.3 kWh usable each, per BigBattery — with the EG4 12000XP V2 off-grid inverter: 12,000W of continuous split-phase 120/240V output, up to 24,000W of PV through two 35A MPPTs, and per EG4 the starting muscle to bring up a 5-ton air conditioner without a soft start. With two or more batteries, the bank supports the inverter's full continuous rating — each NEXUS contributes 140A (about 7.6 kW), per BigBattery. It is an off-grid system; the grid and generator inputs are for charging and bypass, per EG4, not sell-back.

Who This Is For

Full-size off-grid homes running well pumps, HVAC, electric kitchen appliances, and shop tools at the same time — households that cycle the bank every day and want both the output headroom and the storage depth to do it without a generator carrying the evenings. If your loads are cabin-scale, the EG4 6000XP version keeps the same battery platform with a smaller inverter.

Key Features

  • Choose 2 × NEXUS (30 kWh class) or 3 × NEXUS (45 kWh class) — 28.6 or 42.9 kWh usable, adding BigBattery's 14.3 kWh per-unit figure
  • 12,000W continuous split-phase 120/240V output, per EG4; surge rated 18,000W (5 seconds), per BigBattery's kit listing
  • Up to 24,000W of PV input through two 35A MPPTs, per EG4
  • Starts a 5-ton AC without a soft start, per EG4; generator input up to 90A, grid input up to 100A, 100A bypass, per EG4
  • Parallels up to 16 inverters, per EG4; batteries parallel up to 15 units, per BigBattery
  • NEXUS batteries: 6,000+ cycle life, self-heating function, aerosol fire suppression, RS485 / RJ45 / CAN communications, per BigBattery

Why BigBattery

BigBattery is a US company building LiFePO4 energy storage for off-grid and home backup use. NEXUS batteries ship from Texas, carry a 12-Year Limited Warranty, and are backed by lifetime USA-based technical support, per BigBattery — here matched with EG4's high-output XP-series inverter. Browse our EG4 collection for the rest of the line.

What's In the Kit

Solar panels, racking, and array wiring are not included. BigBattery's kit listing does not itemize cables or accessories, so call us at (302) 496-3554 before ordering and we'll confirm exactly what ships with your configuration.

Specifications

Batteries 2 or 3 × BigBattery NEXUS, 48V class (51.2V nominal), LiFePO4, 280Ah each
Usable energy 14.3 kWh per battery, per BigBattery — 28.6 kWh (2 units) or 42.9 kWh (3 units) total
Battery max continuous discharge 140A (7.6 kW) per battery, per BigBattery
Battery cycle life 6,000+ cycles, per BigBattery
Battery communications RS485 / RJ45 / CAN; compatible with all EG4 inverters, per BigBattery
Battery dimensions / weight 19.7 × 27.5 × 15.7 in; approx. 315 lb — each
Inverter EG4 12000XP V2 — 12,000W continuous, split-phase 120/240V, per EG4
Surge 18,000W (5 s), per BigBattery's kit listing
Solar input Up to 24,000W through two 35A MPPTs, per EG4
AC input / bypass Generator up to 90A; grid up to 100A; 100A bypass, per EG4
Inverter parallel capability Up to 16 units, per EG4
Battery warranty 12-Year Limited Warranty, per BigBattery
Inverter warranty 5 years, per BigBattery's kit listing (EG4 warranty terms apply)
Kit SKU K0155 (2 batteries) / K0156 (3 batteries)

Sizing Your Off-Grid Home

Example assumptions for a full-size off-grid home — label and adjust for your own site: refrigerator 1.5 kWh/day, freezer 1.0, lighting 1.0, well pump 1.5, electronics 1.5, laundry and kitchen 3.0, plus air conditioning at roughly 8–15 kWh/day in season depending on tonnage and climate. Call it 17–25 kWh/day in the demanding months.

Two NEXUS (28.6 kWh usable, per BigBattery's per-unit figure) covers about a day of that; three (42.9 kWh) buys the margin that gets you through weather. On power, two batteries support about 280A / 15.2 kW continuous by simple addition of BigBattery's per-unit figures — above the inverter's 12,000W rating — and three raise that ceiling further for surge-heavy homes. A large PV array (the inverter accepts up to 24,000W, per EG4) shortens recovery after cloudy days.

Installation

Each battery cabinet weighs approximately 315 lb, so plan floor space and the move for two or three of them. Wiring 12,000W of split-phase output into a main panel — interconnection, overcurrent protection, grounding, bonding — belongs to a licensed electrician working to the National Electrical Code (NEC) and local codes; most jurisdictions require a permit and inspection for energy storage. Keep the batteries in a dry space above freezing; BigBattery's published charge range starts at 32°F.

Warranty & Support

Batteries: covered by BigBattery's 12-Year Limited Warranty — in BigBattery's words, “BigBattery, Inc. guarantees that its products will be free from defects in material and workmanship for a period of twelve (12) years.” No registration needed, per BigBattery. Inverter: 5-year manufacturer warranty, per BigBattery's kit listing; EG4's warranty terms apply, and EG4 asks that products be registered or accompanied by proof of purchase from an authorized distributor — keep your order confirmation.

BigBattery publishes a 30-Day Money Back Guarantee; per BigBattery, non-defective returns are refunded at purchase price minus a 20% restocking fee, excluding shipping. All returns require a Return Merchandise Authorization (RMA) before anything ships back — call OffGrid Horizon at (302) 496-3554 and we'll open the RMA or warranty claim. We're a family-owned authorized BigBattery partner, and BigBattery backs its batteries with lifetime USA-based technical support.

Shipping

This kit ships as palletized freight within the United States — two or three battery cabinets plus the inverter. Inspect every pallet before signing: note any damage on the delivery receipt and contact us promptly — that notation keeps a freight claim simple.

Frequently Asked Questions

What exactly does the listed price include?

The Battery Configuration you select — two or three NEXUS batteries — plus one EG4 12000XP V2 inverter. The price updates with your selection. Panels and racking are separate.

Can the bank feed 12,000W continuously?

Yes, with two or more batteries: each NEXUS supports 140A (about 7.6 kW) continuous per BigBattery, so two units support roughly 15.2 kW by simple addition.

Two batteries or three?

Size to daily consumption and the weather you want to ride out. Homes near 17–20 kWh/day usually run well at 28.6 kWh usable; heavier use or multi-day cloud points to three. The bank grows later too — up to 15 in parallel, per BigBattery.

Is this a grid-tie system?

No — the 12000XP V2 is an off-grid inverter. Its grid and generator inputs are for charging and bypass, per EG4; it is not sold as a grid-interactive (sell-back) system.

Will it start my air conditioner?

Per EG4, the 12000XP V2 can start a 5-ton AC without a soft start, with 18,000W of 5-second surge per BigBattery's listing. Bring us your nameplate figures and we'll confirm the whole load picture.

Do I need an electrician?

Yes — AC interconnection, grounding, and code compliance are work for a licensed electrician, and most jurisdictions require a permit and inspection.

Planning a whole-home off-grid build? Call OffGrid Horizon at (302) 496-3554 — family-owned, authorized BigBattery partner, and we'll help you size it honestly.

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