48V Off-Grid ESS · NEXUS + EG4 6000XP · Indoor System
14.3kWh of Off-Grid Power From a Pre-Matched Battery and Inverter Pair
This system pairs one BigBattery NEXUS 14.3kWh battery with one transformer-free EG4 6000XP inverter into a single closed-loop off-grid setup — 14.3kWh of storage and 6,000W of continuous output, with up to 8,000W of dual-MPPT solar input. It’s an indoor installation for both components, built for cabins, homesteads, and off-grid homes, and it scales up to 214.5kWh of storage — or 18kW of combined output — on the same platform if you need more later.
What’s In This System
Two components, pre-matched and sold together.
Qty 1
BigBattery NEXUS 14.3kWh
Floor-standing 48V LiFePO₄ battery, expandable up to 15 units in parallel for 214.5kWh total.
Qty 1
EG4 6000XP Hybrid Inverter
6,000W continuous output in a transformer-free design, with dual MPPT solar input up to 8,000W.
What Makes This System Different
14.3kWh NEXUS Battery
LiFePO₄ storage rated for 6,000+ cycles, with a 7.6kW continuous power rating and 270A peak discharge for 1 second.
6,000W Continuous, 12,000W Surge
The EG4 6000XP delivers 6,000W continuously with up to 12,000W of surge headroom (3.5 sec) for motor starts.
Transformer-Free Design
A lighter, more efficient architecture than traditional transformer-based inverters, with less standby power lost as heat.
Dual MPPT, 8kW Solar Input
Two independent MPPT trackers pull up to 8,000W combined, adjusting continuously through the day.
Expandable to 214.5kWh
Up to 15 NEXUS units can run in parallel with additional inverters, for serious long-term capacity growth.
Sub-15ms UPS Transfer
Switches to battery power in under 15 milliseconds, keeping sensitive electronics running through a grid drop without a hard reboot.
6,000+ Cycle Life
The NEXUS battery is rated for years of daily charge and discharge cycles before capacity meaningfully declines.
Advanced BMS Protection
Multi-layer protection on both the battery and inverter for safe, reliable day-to-day operation.
A Pre-Matched Pair, Built for Indoor Installation
Rather than picking a battery and inverter separately and hoping they communicate well together, this system ships as one closed-loop pairing: the NEXUS battery and EG4 6000XP inverter are designed and sold to work with each other directly. The 6000XP’s transformer-free design keeps it lighter and more efficient than older inverter architectures, and it switches to battery power in under 15 milliseconds if the grid drops — close to seamless for anything plugged in at the time.
Worth knowing before installing: this is an indoor system on both sides. The NEXUS battery is specified for indoor, floor-standing installation, and the EG4 6000XP is IP20 — neither is rated for direct outdoor exposure. Plan for a garage, utility room, or dedicated power space. In exchange, the platform scales seriously: up to 15 NEXUS units can run in parallel for 214.5kWh of total storage, and additional 6000XP inverters can be added for up to 18kW of combined output on this bundle’s available configurations.
Full Specifications
Battery — BigBattery NEXUS 14.3kWh (×1)
Capacity
| System voltage | 48 V |
| Nominal voltage | 51.2 V |
| Chemistry | LiFePO₄ |
| Usable energy | 14.3 kWh |
| Ah capacity | 280 Ah |
| Cell configuration | 16S1P |
Charging & Discharge
| Max continuous discharge current | 140 A |
| Max continuous power | 7.6 kW |
| Max discharge peak current | 270A (1 sec) |
| Max charge current | 140 A |
| Charging voltage range | 53.5–57.6 V |
Environmental
| Charge temp range | 32–113°F |
| Discharge temp range | -4–113°F |
| Optimal discharge temp | 59–95°F |
| Humidity range | 10–95%, no condensation |
| Protection rating | IP54, indoor floor-standing |
Physical & Other
| Weight | ~315 lbs |
| Dimensions (W×H×D) | 19.7 × 27.5 × 15.7 in |
| Communications | RS485, RJ45, CAN |
| Max connections | 15 parallel (214.5kWh) |
Inverter — EG4 6000XP (×1)
Output
| Output power | 6,000 W |
| Surge capacity | 12,000W (3.5s) / 11,000W (5s) |
| Output voltage | 120/240 Vac split-phase |
| Max continuous output current | 25A @ 240V |
| Switching time | <15ms single / <30ms parallel |
Solar & Charging
| MPPT channels | 2 (1 input each) |
| Max PV array power | 8,000W (4,000W/MPPT) |
| Max discharge current | 140 A |
| Max charge current | 125 A |
AC Input & Bypass
| Max AC input power | 9,000 W |
| AC bypass | 50 A |
| Battery voltage range | 46.4–60 Vdc |
Physical & Other
| Dimensions (D×W×H) | 5.25 × 18 × 25.5 in |
| Weight | 52.9 lbs |
| Protection rating | IP20, indoor only |
| Parallel capacity | Up to 16 units |
Operating temperature: 32–113°F. Certification: UL1741.
Other Configurations Available
This same NEXUS and EG4 6000XP platform is sold in several sizes. The row below highlighted in your brand color is the configuration this page describes — everything else is shown for reference if a customer needs a different scale.
| Tier | Inverters | Batteries | Capacity | Max Output |
|---|---|---|---|---|
| 1x Inverter | 1× | 1× | 14.3 kWh | 6 kW |
| 1x Inverter | 1× | 2× | 28.6 kWh | 6 kW |
| 1x Inverter | 1× | 3× | 42.9 kWh | 6 kW |
| 2x Inverter | 2× | 2× | 28.6 kWh | 12 kW |
| 3x Inverter | 3× | 3× | 42.9 kWh | 18 kW |
Common Questions
What exactly is included in this system?
One BigBattery NEXUS 14.3kWh battery and one EG4 6000XP hybrid inverter, sold as a pre-matched closed-loop pair — 14.3kWh of storage and 6,000W of continuous output.
Can this system be installed outdoors?
No — both components are indoor-rated. The NEXUS battery is specified as indoor floor-standing, and the EG4 6000XP inverter is IP20. Plan for a garage, utility room, or dedicated indoor power space.
How is this different from the APEX-based NEXUS bundles?
The EG4 6000XP is a transformer-free design, which trims weight and standby losses compared to the APEX inverters’ transformer-based construction, and it switches to battery power in under 15ms if the grid drops. It also parallels up to 16 units on its own platform, well beyond the APEX line’s 6-unit limit, for systems that need to scale further.
Will this run my entire house?
It depends on your total connected load. At 6,000W continuous (12,000W surge) it covers most efficient homes and cabins comfortably, but a full load calculation is worth doing before sizing your system — especially with well pumps, electric heat, or several large appliances running together.
Can I expand this system later?
Yes — up to 15 NEXUS battery units can run in parallel for 214.5kWh of total capacity, and the EG4 6000XP itself parallels up to 16 units for more combined output.
What’s the warranty on this system?
The NEXUS battery carries a 12-year manufacturer’s warranty and the EG4 6000XP inverter carries a 10-year manufacturer’s warranty — two separate coverage periods for the two components.
Do I need a licensed electrician to install it?
Given the voltages and currents involved, installation should be handled by a qualified, licensed electrician or solar installer familiar with your local code requirements.
Battery — BigBattery NEXUS
Inverter — EG4 6000XP
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