48V Hybrid Inverter · Dual AC Input — Grid + Generator
6,500 Watts of Off-Grid Power, With Solar, Grid, and Generator Running Together
The APEX-6.5K converts stored DC power from a 48V lithium battery bank into full-strength 120/240V split-phase household electricity — the same clean, pure sine wave power you’d get from a utility line. Unlike single-input inverters, it keeps a dedicated grid connection and a dedicated generator connection wired in side by side, so cabins, homesteads, and off-grid residences can lean on solar by day and fall back on either backup source without swapping a plug.
What Makes the APEX-6.5K Different
6.5kW Continuous, 13kW Surge
Rated for 6,500W of continuous output with up to 13,000VA of surge headroom to start motors, pumps, and compressors without tripping.
True Split-Phase Sine Wave
120/240V pure sine wave at 50/60Hz — the same wave shape a utility delivers, safe for motors, electronics, and anything sensitive to rough power.
Dual MPPT Solar Charging
Two independent MPPT trackers pull up to 10,000W combined, adjusting continuously as sunlight shifts through the day.
Solar, Grid & Generator Together
Two separate AC inputs let grid and generator both stay connected at once, with solar charging independently on top — no manual switchover.
80A Pass-Through
Routes up to 80A straight to critical loads — enough to carry a well pump or HVAC run without staging separate circuits.
Parallel Up to 6 Units
Stack multiple APEX-6.5K units for larger homes, or connect three or more to generate a full three-phase output.
Layered Protection
Guards against over/under-voltage, overload, short-circuit, and overheating, tripping a safe shutdown instead of letting a fault spread.
14°F to 131°F Range
Keeps working from well below freezing up to 131°F, derating only once temperatures climb past 113°F.
Two Backup Paths, One Compact Footprint
Most off-grid inverters make you choose between a grid connection and a generator connection at any given moment. The APEX-6.5K keeps both wired in permanently — two independent MPPT solar trackers cover day-to-day charging for a combined 10,000W, and when the sun isn’t enough, the system can draw from utility power and a generator at the same time instead of switching between them.
At 48 lbs and roughly 25.5 × 16 × 5.5 inches, it’s noticeably more compact than the larger APEX-10K, which matters when floor space in a utility room or power shed is tight. The same 14°F to 131°F operating range and layered protection against over-voltage, over-current, short circuits, and heat buildup carry over, so a fault trips a safe shutdown instead of spreading through the rest of the system.
Full Specifications
Output
| Rated output power | 6,500 W |
| Max output (surge) | 13,000 VA |
| Output voltage | 120/240 Vac split-phase |
| Frequency | 50/60 Hz |
| Waveform | Pure sine wave |
| Motor load capacity | 4 HP |
| Switching time | 10 ms (typ.) |
| Max efficiency | 99.9% |
Battery & Charging
| Battery type | Li-ion / lead-acid / user-defined |
| Rated battery voltage | 48V |
| Battery voltage range | 40–60 Vdc |
| Max grid/gen charge current | 80 A |
| Max hybrid charge current | 140 A |
| Max solar charge current | 140 A |
Solar Input
| MPPT channels | 2 (1+1) |
| Max solar input power | 5,000W + 5,000W |
| Max input current | 18A + 18A |
| Max open circuit voltage | 550 Vdc / channel |
| MPPT voltage range | 125–450 Vdc |
| MPPT tracking efficiency | 93% |
AC Input & Bypass
| AC input | 2 inputs, grid + generator* |
| Input voltage range | 65–140 Vac |
| Input frequency range | 50/60 Hz |
| Bypass overload current | 40 A |
| Pass-through capacity | 80 A |
Physical & Environmental
| Dimensions | 25.51 × 16.14 × 5.51 in |
| Weight | 48 lbs |
| Ingress protection | IP20 (indoor only) |
| Operating temperature | 14–131°F |
| Noise level | <60 dB |
| Cooling | Intelligent fan |
Connectivity, Protection & ID
| Communication | RS485 / CAN / USB / dry contact / CT |
| Optional module | Wi-Fi / GPRS |
| Integrated breakers | Utility / load / battery / PV |
| Parallel capacity | Up to 6 units, 3-phase at 3+ |
| Brand / model | BigBattery APEX-6.5K |
| GTIN | 00199874185712 |
*Grid and generator each get their own dedicated AC input and can be connected simultaneously. Certifications: UL1741, RoHS, EN61000-6-1, EC61000-6-3, FCC Part 15 Class B, IEC62109-1/2.
Battery Compatibility
Built around 48V lithium battery banks (40–60Vdc), with full closed-loop communication for the packs below. Other 48V lithium or lead-acid batteries can run as a user-defined battery type, just without the live communication link.
- BigBattery NEXUS
- BigBattery ETHOS
- BigBattery HUSKY2 INV
- EG4 280Ah All-Weather / Indoor
- EG4 314Ah All-Weather / Indoor
Common Questions
Will the APEX-6.5K run my entire house?
It depends on your total connected load. At 6,500W continuous (13,000VA surge) it comfortably covers most efficient homes and cabins, but a full load calculation is worth doing before sizing your system — especially if you’re running well pumps, electric heat, or several large appliances at once.
Can solar, grid, and a generator all run at the same time?
Yes. The APEX-6.5K has two independent AC inputs — one for grid, one for generator — plus solar charging on its own circuit, so all three can stay connected simultaneously. (The larger APEX-10K shares a single AC input between grid and generator instead.)
What batteries does it work with?
Any 48V lithium battery bank works as a general-purpose battery. Full closed-loop communication is supported with BigBattery NEXUS, ETHOS, and HUSKY2 INV, plus EG4’s 280Ah and 314Ah packs.
Can it be installed outdoors?
No — it’s rated IP20, meaning indoor or fully enclosed installation only, such as a garage, utility room, or dedicated power shed.
Can I connect more than one unit?
Yes, up to six units can be paralleled together, and three or more can be configured to produce a three-phase output for larger installations.
How does this compare to the APEX-10K?
The APEX-10K outputs more power (10,000W vs. 6,500W continuous) and suits larger homes, but shares one AC input between grid and generator. The APEX-6.5K trades some output capacity for two independent AC inputs, a smaller footprint, and about 14 lbs less weight — a better fit where simultaneous grid-and-generator backup matters more than maximum wattage.
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.
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