Product Description

This is the full-output configuration of the NEXUS + APEX line: two or three BigBattery NEXUS 48V LiFePO4 batteries — 280Ah and 14.3 kWh usable each, per BigBattery — with the APEX 10K all-in-one inverter: 10,000W of continuous split-phase 120/240V output, 20,000VA maximum, two MPPT solar inputs rated 5,000W + 5,500W, and built-in charging from grid or generator, per BigBattery. With two or more batteries, the bank supports the inverter's full continuous rating — each NEXUS contributes 140A (about 7.6 kW) per BigBattery. BigBattery sells this as an off-grid and backup power system; it is not sold as a grid-interactive (sell-back) system.

Who This Is For

Full-size off-grid homes and working properties that run heavy simultaneous loads — well pump, HVAC, kitchen, and shop equipment together — and cycle the bank daily. The 10K inverter provides the headroom; 30–45 kWh class storage carries the nights and cloudy weather. If your loads are cabin-scale, the APEX 6.5K 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
  • 10,000W continuous split-phase 120/240V output, 20,000VA maximum output, per BigBattery
  • Two MPPT solar inputs, 5,000W + 5,500W (125–450Vdc MPPT range, 550Vdc max open-circuit), per BigBattery
  • Up to 200A solar charging, up to 120A grid/generator charging; one AC input (grid or generator); UPS backup capability (15–30ms), per BigBattery
  • NEXUS batteries: 6,000+ cycle life, self-heating function, aerosol fire suppression, RS485 / RJ45 / CAN communications, per BigBattery
  • Room to grow: NEXUS parallels up to 15 units and the APEX 10K parallels up to 6 units, per BigBattery
  • Inverter certifications: UL1741 / RoHS / EN61000-6-1 / EC61000-6-3 / FCC Part 15 Class B / IEC62109-1 / IEC62109-2, per BigBattery

Why BigBattery

BigBattery is a US company building LiFePO4 energy storage for off-grid and home backup use; the APEX line is BigBattery's own inverter family, so battery and inverter come from one manufacturer. Kits ship from Texas and are backed by lifetime USA-based technical support, per BigBattery. See our full BigBattery collection.

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
Battery dimensions / weight 19.7 × 27.5 × 15.7 in; approx. 315 lb — each
Inverter APEX 10K — 10,000W rated output, 20,000VA maximum, split-phase 120/240Vac
Solar input Two MPPTs, 5,000W + 5,500W; 125–450Vdc MPPT range; 22A + 22A; 550Vdc max open-circuit
Charging Up to 200A from solar; up to 120A from grid/generator; one AC input (grid or generator)
Inverter parallel capability Up to 6 units, per BigBattery
Inverter certifications UL1741 / RoHS / EN61000-6-1 / EC61000-6-3 / FCC Part 15 Class B / IEC62109-1 / IEC62109-2, per BigBattery
Inverter dimensions / weight 28.46 × 17.64 × 5.91 in; 62 lb
Battery warranty 12-Year Limited Warranty, per BigBattery
Inverter warranty 5-Year Limited Warranty, per BigBattery
Kit SKU K0197 (2 batteries) / K0198 (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 with margin; three (42.9 kWh) buys the second day that gets you through weather without running a generator. On power, two batteries support about 280A / 15.2 kW continuous by simple addition of BigBattery's per-unit figures — comfortably above the inverter's 10,000W rating — and three add margin for surge-heavy loads.

Installation

Each battery cabinet weighs approximately 315 lb, so plan floor space and the move for two or three of them, plus wall space for the 62 lb inverter. The AC side — 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.” Included accessories are covered for 1 year, and no registration is needed, per BigBattery. Inverter: the APEX 10K is covered by a 5-Year Limited Warranty, per BigBattery.

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 with BigBattery. We're a family-owned authorized BigBattery partner, and BigBattery backs the system 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 APEX 10K inverter. The price updates with your selection. Panels and racking are separate.

Can the bank actually feed 10,000W 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 — above the inverter's full rating.

Two batteries or three?

Size to daily consumption and the weather you 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 can also grow later — up to 15 in parallel, per BigBattery.

Is this a grid-tie system?

No. BigBattery sells it for off-grid and backup power applications; the AC input accepts grid or generator power for charging, per BigBattery.

Will it start large motors?

BigBattery rates the APEX 10K at 20,000VA maximum output for short-duration demands above its 10,000W continuous rating. Bring us the nameplate figures on your well pump or compressor and we'll confirm the 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.

Running the numbers on a whole-home system? Call OffGrid Horizon at (302) 496-3554 — family-owned, authorized BigBattery partner, straight answers.

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