Bluetti AC500 + B300K

~$2,999approx. list price

800 WLights, phones, router, a CPAP
2,200 WFridge, freezer and the essentials
4,000 WFurnace blower, sump pump or a window AC
7,500 WWell pump or a small central AC
18,000 WWhole home with central air

5,000 W running, 10,000 W surge — sustains the furnace blower, sump pump or a window AC tier and everything below it.

Best forTransfer-switch homes needing maximum surge capacity for well pumps, compressors, and HVAC.

Bluetti's modular tower system: a 5,000W inverter head (10,000W surge - the strongest surge rating of any portable here) that stacks on B300K batteries. The 50A NEMA 14-50 outlet plus L14-30 makes transfer-switch and RV-pedestal hookups trivial, and two AC500s can pair for 240V and 33kWh. Costco has carried the combo, which says something about mainstream acceptance. The batteries charge to 80% in 45 minutes and detach for transport, since the two-piece design splits an unliftable 131 lbs into two 65-lb pieces. Recurring complaints: the fans cycle between off and full speed when running off-grid, remote Wi-Fi access drops out, and the 4-year/3+1 warranty structure trails the 5-year industry standard. It's older than the Apex 300 but the 5kW inverter and 14-50 outlet still earn it recommendations for heavy transfer-switch duty.

From the spec sheet

Specifications

Battery capacity: 2,765 Wh
Expandable to: 33,178 Wh
Continuous output: 5,000 W
Surge output: 10,000 W
Runtime: Fridge (~150W): ~15.5 hrs on base combo

Type: Power Station
Fuel: Battery (LiFePO4)
Outlets: 6x AC incl. 30A TT-30 & L14-30, 50A NEMA 14-50, 2x 100W USB-C, 4x USB-A, wireless pads
Transfer-switch ready: Yes
Weight: 131 lbs
Warranty: 4-year (inverter), 3+1yr battery
Model: AC500 + B300K

5,000W / 10,000W surge·50A NEMA 14-50 outlet·Modular two-piece design

At a glance

Strengths

+10,000W surge starts motor loads nothing else portable will
+NEMA 14-50 (50A) + L14-30 - best transfer-switch hookup options in class
+Modular: splits into two ~65-lb pieces for transport
+Expands to 16.6kWh per inverter, 33kWh/240V with two
+B300K packs are cheap and cross-compatible with Apex 300
+16 total outlets including wireless pads

At a glance

Drawbacks

−Loud fans at high charge/discharge - garage unit, not living-room unit
−Wi-Fi/app connectivity drops are a recurring owner complaint
−4-year inverter / 3+1 battery warranty trails the 5-year standard
−Aging platform - Apex 300 gets Bluetti's new features first
−No wheels on either piece

Summarised from owner discussions and forums

Owner insights

The AC500 is the head unit owners built home systems around before the Apex 300 existed: a 5,000W, 120V inverter with a 14-50 that can feed a whole panel, two high-voltage solar inputs, and detachable B300S or B300K packs. Owner setups run from one head on an interlock to two heads in split phase with 15 panels, and single-head owners cycling it daily report years of use and lower bills. The recurring warning is about split phase rather than the single unit.

A single AC500 feeding 120V circuits through a transfer switch or interlock is the simpler setup; an owner feeds a whole panel that way with the 240V breakers off. Two heads in split phase are where the problems cluster: systems that drop the house when the grid flickers or fails, master and slave batteries drifting apart until one side empties and shuts everything off, and setup that stalls with support answering by email every couple of days. Smaller irritations show up too: grid-flicker alarms on marginal supply, Wi-Fi that needed a trip to the front panel, fans that ran hard until clogged filters were cleaned, and a run of battery and cable generations that confuses anyone expanding. Solar is its strength, with 150V inputs that take residential series strings.

120V muscle and a large solar array are the reasons to buy it, along with a clearance price like the $1,999 Costco deal. Owners who need 240V now weigh a second AC500 against an Apex 300 that does 240V in one box but limits each solar input to 60V, and in 2025 one owner weighed moving to the Apex while keeping their B300K packs. The Anker F3800 Plus and EcoFlow DELTA Pro Ultra come up as the one-box split-phase designs owners wished Bluetti had built.

What owners like

+5,000W of 120V from one head can feed a whole panel through the 50A plug: an owner runs the entire panel that way and simply switches off the breakers for a 240V pump and the central air
+Each of the two solar inputs accepts up to 150V, enough for an owner to run three 405W residential panels in series on one input, a string the 60V-limited Apex 300 cannot take without extra hardware
+Paired in split-phase mode, two heads give real 240V: an owner with 15 panels runs a pool pump for nine hours a day and the whole house on battery from 7pm to about 5am, another powers a small barn apartment on 50A, 240V service
+Owners report long service: one has run it with five panels for two years and cut energy bills, another has had two AC500s in place for close to four years, and an owner in Germany runs one 24/7, charging by day and discharging overnight
+Wall charging is quick for the class: an owner watched a B300S fill in about two hours at 2kW from the grid, and another charges the AC500 at over 2,400W
+The home integration kit and batteries carry over: Bluetti says B300S and B300K packs work with the Apex 300, and an AC500 50A charging cable only needs swapping for the P050A
+Deal pricing has been steep in its late life, including the AC500 with a B300K at Costco for $1,999 in September 2026

Common complaints

−Split-phase pairs have dropped the whole house when the grid fails or flickers: owners in 2023 and 2024 describe both heads cutting output on grid loss, or switching off and on through every brownout with only 200-300W per side, until someone resets them
−Master and slave drift apart in a split-phase pair (an owner saw 24% against 7%), and when either side empties all AC output stops instead of the fuller unit carrying on
−Packs on one head drain unevenly at light loads, with a 2023 owner of a four-B300S stack seeing packs at very different levels; full drain-and-recharge calibration helps only for a while
−One AC500 is 120V only, so a 240V dryer or well pump means a second head in split phase, and by mid-2025 an owner at that point was weighing an Apex 300 instead; that August another owner could no longer find the AC500 on Bluetti's own site
−Battery and cable generations are confusing: the original B300 does not fit, the B300S was discontinued, mixing in B300K packs needs a P150D-to-P090D cable an owner could not find on Bluetti's website, and another owner needs about two feet of side clearance for the stiff stock cables
−Grid-quality alarms are a recurring nuisance: Grid Flicker error 68, low-voltage and low-frequency alarms when charging and powering loads together, and a high-frequency error when charging from a generator
−Wi-Fi is the weak link: an off-grid cabin owner twice had remote access switch itself off until someone re-enabled it at the front panel, another could not get it to join a network that has no password, and firmware updates hide behind the Bluetooth menu
−Fans can end up running flat out: one daily-cycling owner traced it to clogged exhaust filters behind the left side shell, which have to come off for cleaning
−Warranty is 4 years on the inverter and 3+1 on the batteries, and a split-phase buyer in 2025 got only email support, one response every 48 hours, while unable to lock in master and slave settings

Questions owners ask

Do I need two AC500s to back up my house?

Only for 240V loads. One AC500 outputs 120V; a buyer whose only 240V circuit was a dryer they would skip in an outage was told one unit is enough, and one owner feeds an entire panel through the 50A plug with the breakers for a 240V pump and the central air switched off. A 240V dryer, pump or air conditioner needs two heads in split phase.

Why does my split-phase AC500 system shut off when the grid drops?

Two owners with split-phase pairs have reported it: one on a Fusion Box saw output cut whenever the grid failed, and the other saw both units switch off and on through a brownout until someone reset them. A third owner's pair shut down all AC output when one side's battery ran out. If uninterrupted switchover matters, test it by killing the grid feed before relying on it.

Which batteries and cables work with the AC500?

B300S and B300K packs; the original B300 uses a different plug and will not fit. The B300S has been discontinued, so new expansion is B300K, which connects to the AC500 with a P150D-to-P090D cable that one owner could not find on Bluetti's website. Check that every cable lock is seated: an owner found a pack with a slipped lock still showing its charge while contributing nothing.

How long can solar strings run on the AC500's 150V inputs?

Each input takes up to 150V and about 15A, and the 150V figure is the hard limit; one owner understands the unit limits current safely above 15A. That leaves room for three typical residential panels in series: an owner runs three 405W panels in series on one input. Keep cold-weather open-circuit voltage under 150V.

Should I add a second AC500 or switch to an Apex 300 for 240V?

One AC500 owner weighing this in 2025 leaned toward an Apex 300 plus another B300K, which would cost about the same as a second AC500 once the split-phase cable is counted. The Apex does 120V and 240V from one unit; the trade-offs are its 60V solar inputs and an AC500 left idle until it gets batteries of its own, and the AC500 does have a bit more output.

Head to head