BigBattery | NEXUS + APEX-6.5K Off-Grid System | K0191

Introducing the APEX Inverter Series

The BigBattery APEX Off-Grid Hybrid Inverter Series (6.5K & 10K) is engineered for dependable, whole-home energy independence. Available in two power classes to suit a wide range of system sizes, both models deliver true split-phase 120/240V output at 50/60Hz with clean, pure sine-wave power. Designed to integrate seamlessly with modern 48V LiFePO₄ battery banks, the APEX series provides stable, efficient performance for demanding off-grid applications.

Built for real-world autonomy, APEX supports solar, grid, and generator inputs, allowing your system to remain powered around the clock—regardless of weather, season, or location.

Built for Demanding Loads and Harsh Environments

The APEX series is designed to handle high-demand electrical loads with confidence. An 80A AC pass-through capability allows large appliances and critical circuits to operate smoothly, while wide operating temperature ranges ensure reliable performance across varying climates. Thoughtful design elements such as installer-friendly bottom-entry wiring, integrated circuit breakers, and comprehensive electronic protections make APEX a rugged and practical foundation for cabins, homesteads, remote residences, and off-grid properties.

Whole-Home Split-Phase Power

Both APEX models deliver true 120/240V split-phase power, enabling operation of larger appliances, well pumps, HVAC components, and essential household circuits. The pure sine-wave output ensures compatibility with sensitive electronics, making APEX ideal for full off-grid homes and demanding residential installations.

Solar-Ready Hybrid Operation

The APEX-6.5K supports simultaneous solar and generator inputs, allowing seamless charging and load support when sunlight is limited. When solar production drops, a generator can automatically maintain system operation without interruption.
Input configurations differ between models—refer to the specification sheet for full details.

Off-Grid Reliability by Design

With integrated protections and a clean wiring layout, the APEX inverter is designed for long-term reliability in remote environments. Built-in safeguards protect against overloads, voltage irregularities, temperature extremes, and short circuits—helping ensure safe and dependable system operation over time.

Go Big on Power

When paired with the NEXUS battery system, the APEX inverter series forms a complete, high-performance energy storage solution for off-grid enthusiasts. Whether powering a compact cabin, a tiny home, or a large ranch property, this ESS is designed to maximize energy independence, protect against outages and blackouts, and keep your system running when it matters most.

Inverter Input Overview

Both APEX-6.5K and APEX-10K support grid, load, battery, PV, parallel connections, USB, Wi-Fi, RS485/CAN, and dry contact communication.

• CT input is available on the APEX-6.5K only.

• APEX-10K uses a single AC input that supports either grid or generator (not simultaneously).

Inverter Performance Highlights

• Rated Output Power

  • APEX-6.5K: 6,500W

  • APEX-10K: 10,000W

• Maximum Output Power

  • APEX-6.5K: 13,000VA

  • APEX-10K: 20,000VA

• Motor Load Capacity

  • APEX-6.5K: up to 4 HP

  • APEX-10K: up to 6 HP

• Battery System

  • 48V nominal system

  • 40–60Vdc operating range

  • Compatible with lithium-ion, lead-acid, and user-defined battery profiles

• Solar Input (Dual MPPT)

  • APEX-6.5K: 5,000W + 5,000W

  • APEX-10K: 5,000W + 5,500W

  • MPPT voltage range: 125–450Vdc

• Charging Capability

  • Max solar charge current: up to 200A

  • Max grid/generator charge current: up to 120A

• Efficiency

  • Maximum inverter efficiency: 99.9%

  • MPPT tracking efficiency: up to 93%

• Parallel Operation

  • Up to 6 units in parallel

  • Three-phase output supported with more than three units

Protection, Compliance, and Reliability

The APEX inverter series includes extensive built-in protections, including PV input current limiting, over-voltage and under-voltage protection, battery over-current safeguards, thermal protection, overload shutdown logic, and short-circuit protection. Intelligent fan cooling keeps noise below 60dB, while UL and international certifications ensure compliance with industry safety standards.

Each inverter is backed by a 5-year warranty, providing long-term confidence in performance and durability.