BLUETTI’s Apex 300 and its older AC300 are both 3kW-class home backup systems, but they’re built very differently: the Apex 300 puts a 2,764.8Wh LiFePO4 battery and a 3,840W inverter in one 83.8-pound box, while the AC300 is a 3,000W inverter head with no battery inside that needs at least one B300 or B300K pack to run, according to BLUETTI’s user manuals, product pages and its own AC300 vs Apex 300 comparison. The Apex 300 adds a 120V/240V output switch, a 50A L14-50R outlet, 3,840W charging and room for up to six B300K batteries per unit. The AC300 counters with higher-voltage solar inputs that accept up to 150V and a modular design that splits the weight into two pieces. Here’s how they compare, with worked runtime and solar estimates.
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Specs come from the Apex 300 user manual (V1.1, section 13), BLUETTI’s AC300 + B300 product page and AC300 user manual, BLUETTI’s August 2025 comparison article, and the Amazon listings for the BLUETTI Apex 300 and BLUETTI AC300 + B300. I haven’t tested either system, so runtimes and charge times are labeled estimates.
Short answer
- Apex 300: the better pick for most new buyers. One box, more output (3,840W vs 3,000W), 240V from a single unit, 0 ms UPS in the right setup, faster charging and far more expansion.
- AC300: still worth a look if you already own B300 or B300K batteries, want to carry the system in two lighter pieces, or have solar panels wired in high-voltage series strings up to 150V.
AC300 vs Apex 300 spec table
| Spec | BLUETTI AC300 | BLUETTI Apex 300 |
|---|---|---|
| Design | Inverter head only; needs B300 (3,072Wh) or B300K (2,764.8Wh) | All-in-one: inverter + 2,764.8Wh battery (51.2V, 54Ah) |
| Battery chemistry | LiFePO4 (in B300/B300K) | LiFePO4 |
| Rated cycle life | 3,500 (per BLUETTI comparison) | 6,000+ to 80% |
| Continuous AC output | 3,000W | 3,840W (1,920W max per pair of 20A outlets) |
| Surge / lifting | 6,000W | 7,680W |
| AC outlets | 6 × 120V/20A + 1 × TT-30R | 4 × NEMA 5-20R, 1 × TT-30R (3,600W), 1 × L14-50R (3,840W, 120V/240V) |
| 240V | Two AC300s + P030A fusion box (split phase) | Single unit via 120V/240V switch on the L14-50R and P050A |
| Wireless charging | 2 × 15W pads | None |
| AC charging | Up to 3,000W | Up to 3,840W (80% in 45 min); 1,800W from a standard 15A input |
| Solar input | 2,400W total, two MPPT inputs, 12–150V, 12A each | 2,400W total, two XT60 inputs, 1,200W each, 12–60V, 20A |
| AC + solar charging | 5,400W with two or more B300s | 3,840W single unit; 6,240W in parallel |
| UPS switchover | 20 ms | 0 ms (240V input, specific outlets) or ≤20 ms |
| Max capacity per unit | 12,288Wh (4 × B300) | 19,353.6Wh (Apex 300 + 6 × B300K) |
| Max system | 22.1kWh (2 × AC300, 8 batteries, P030A) | About 58kWh and 11.52kW (3 × Apex 300, 18 B300K, Hub A1) |
| Weight | 47.62 lb inverter head, plus battery | 83.78 lb (38 kg) total |
| Size | 20.5 × 12.5 × 14.1 in (head) | 20.67 × 12.87 × 12.6 in |
| App | Wi-Fi + Bluetooth | Wi-Fi + Bluetooth |
All-in-one vs modular
The AC300 was designed as a stack: an inverter head on top of one or more batteries. That means you can carry it in two pieces, swap or add batteries, and keep using existing B300 or B300K packs. It also means it can’t run anything without a battery attached.
The Apex 300 folds the battery into the main unit. It weighs about 84 pounds in one piece, which is heavier to lift than either half of an AC300 stack but simpler to set up. Extra B300K batteries plug into its expansion port when you need more capacity.
Output: 3,000W vs 3,840W, and 240V
The Apex 300’s 3,840W is 28% more continuous power than the AC300’s 3,000W. Its manual notes a limit of 1,920W per pair of 20A outlets, so spread big loads across pairs or use the TT-30R (3,600W) or L14-50R (3,840W) outlets for the heaviest ones.
The bigger change is 240V. A single Apex 300 has a switch that sets the L14-50R and P050A port to 120V or 240V, so one unit can run 240V appliances within its 3,840W limit. The AC300 is 120V on its own; for 240V you need two AC300s joined by BLUETTI’s P030A fusion box for split-phase output. If you want to back up a 240V well pump or dryer circuit, that difference matters. My explainer on surge watts vs running watts helps you check whether a motor’s starting spike fits.
Worked runtime estimates
| Load (typical draw) | AC300 + 1 B300 (3,072Wh)* | Apex 300 alone (2,764.8Wh)* |
|---|---|---|
| Full-size fridge, about 60W average | ≈ 43 hr | ≈ 39 hr |
| Internet + laptop + lights, 150W | ≈ 17 hr | ≈ 16 hr |
| Gas furnace blower, 400W | ≈ 6.5 hr | ≈ 5.9 hr |
| Well pump, 1,000W running | ≈ 2.6 hr of pump time | ≈ 2.4 hr of pump time |
| Window AC, 1,200W | ≈ 2.2 hr | ≈ 2.0 hr |
| Electric dryer, 3,000W (240V on Apex) | Needs two AC300s for 240V | ≈ 47 min |
*Estimate: rated Wh × 0.85 ÷ load. Example for the Apex 300 and a 400W furnace blower: 2,764.8 × 0.85 ÷ 400 ≈ 5.9 hours. My guide on how many watts a refrigerator uses explains why fridge averages are far below their label.
With expansion batteries
| Configuration | Total capacity | 500W average home load* |
|---|---|---|
| AC300 + 2 × B300 | 6,144Wh | ≈ 10.4 hr |
| AC300 + 4 × B300 | 12,288Wh | ≈ 20.9 hr |
| Apex 300 + 2 × B300K | 8,294.4Wh | ≈ 14.1 hr |
| Apex 300 + 6 × B300K | 19,353.6Wh | ≈ 32.9 hr |
*Estimate: total Wh × 0.85 ÷ 500W. A 500W average covers a fridge, freezer, lights, internet, TV and a furnace blower cycling. My guide on how many batteries it takes to power a house shows how to work out your own average.
Charging from the wall and a generator
The AC300 accepts up to 3,000W of AC charging. The Apex 300 accepts up to 3,840W through its P050A port, which BLUETTI says reaches 80% in about 45 minutes at room temperature. From an ordinary 15A household outlet, the Apex 300 is limited to 1,800W including pass-through. Through the 50A P050A connection, its bypass and charging capacity reaches 6,000W at 120V or 12,000W at 240V, so it can pass a generator or grid supply through to loads while it charges. My comparison of generator vs battery backup covers how the two work together.
Solar: same 2,400W, very different wiring
Both systems top out at 2,400W of solar from two inputs, but their voltage windows aren’t alike:
- AC300: two MPPT inputs, each 12–150V at 12A. You can wire panels in series up to 150V open-circuit, which keeps current low and lets you use thinner, longer cable runs.
- Apex 300: two XT60 inputs, each 12–60V at 20A and up to 1,200W. The manual warns not to exceed 60V open-circuit, so larger arrays need panels wired in parallel or 2-series strings of low-voltage panels. BLUETTI sells an optional SolarX 4K controller for adding more, higher-voltage solar.
| Solar array | AC300 + B300 (3,072Wh)* | Apex 300 (2,764.8Wh)* |
|---|---|---|
| 800W (about 560W real) | ≈ 5.5 hr | ≈ 4.9 hr |
| 1,600W (about 1,120W real) | ≈ 2.7 hr | ≈ 2.5 hr |
| 2,400W (about 1,680W real) | ≈ 1.8 hr | ≈ 1.6 hr |
*Estimates assume about 70% of panel rating in good sun; hours = Wh ÷ real watts. To use the full 2,400W on the Apex 300, each input needs about 1,200W at 60V or below, which means high-current parallel wiring. My MPPT vs PWM guide explains why voltage and current limits matter.
UPS behavior
The AC300 switches to battery in 20 ms. The Apex 300 manual describes two UPS levels: 0 ms when the unit is set to 240V and loads are connected to specific outlets, and 20 ms or less otherwise. Zero-millisecond switchover is meant for sensitive gear like desktop PCs, NAS drives and networking equipment that can reboot on even a brief drop.
Home integration
Both can feed a home circuit through a transfer switch or inlet box. For the AC300, 240V split-phase backup needs two units and the P030A fusion box. For the Apex 300, a single unit supplies 120V or 240V, and three units can run in parallel through BLUETTI’s Hub A1 for about 11.52kW and 58kWh of storage. Any panel connection should be done by a licensed electrician; my article on transfer switches vs interlock kits explains the options.
Setup basics from the Apex 300 manual
- Update firmware first. BLUETTI recommends updating to the latest firmware through the app before first use.
- Charge to full before relying on it for backup.
- Set 120V or 240V with the output switch. In parallel mode the switch is disabled and output defaults to 240V.
- Keep each solar input at 60V open-circuit or less.
- For storage beyond three months, charge to 40–60% and power it off, then cycle it every three months.
Who should buy which
| Your situation | Better fit | Why |
|---|---|---|
| New buyer planning home backup | Apex 300 | 3,840W, single-unit 240V, 19.4kWh per unit |
| Need 240V for a well pump or dryer | Apex 300 | One unit does it; AC300 needs two plus a fusion box |
| Running a home office with sensitive PCs | Apex 300 | 0 ms UPS in 240V mode |
| Already own B300 or B300K batteries | AC300 | Reuse them with a new inverter head |
| Long solar cable runs with series strings | AC300 | 12–150V inputs vs 12–60V |
| Need to carry it up stairs alone | AC300 | Splits into lighter pieces |
FAQ
Is the Apex 300 the replacement for the AC300?
BLUETTI describes the Apex 300 as the next generation after the AC300, introduced about two years later, with an all-in-one design, more output and more expansion.
Can the AC300 work without a battery?
No. The AC300 is an inverter head and needs at least one B300 or B300K battery connected.
Can a single Apex 300 output 240V?
Yes. A switch sets its L14-50R outlet and P050A port to 120V or 240V, within the 3,840W limit.
Does the Apex 300 work with B300 batteries?
BLUETTI’s documentation lists the B300K as the Apex 300’s expansion battery, up to six per unit. Check BLUETTI’s compatibility list before reusing older packs.
How fast does the Apex 300 charge?
Up to 3,840W from AC through the P050A connection, reaching 80% in about 45 minutes per BLUETTI. A standard 15A outlet limits it to 1,800W.
Which handles more solar?
Both accept 2,400W from two inputs. The AC300 takes up to 150V per input; the Apex 300 is limited to 60V per input unless you add BLUETTI’s SolarX 4K.
How long will the Apex 300 run a refrigerator?
About 39 hours for a fridge averaging 60W (estimate).
Which lasts more cycles?
BLUETTI rates the Apex 300 at 6,000+ cycles to 80% and lists 3,500 cycles for the AC300 system.
Bottom line
The Apex 300 is the more capable system for most buyers: 3,840W, 240V from a single unit, 0 ms UPS in 240V mode, 3,840W charging and up to 19.4kWh per unit in one integrated box. The AC300 remains a sensible choice when you already own BLUETTI batteries, need to move the system in lighter pieces, or want to run high-voltage solar strings up to 150V without an add-on controller.