Head-to-head test
BLUETTI AC500 + 2×B300K vs BLUETTI EP900 + 2×B500
The AC500 stack hands you sockets; the EP900 hands you back your breaker panel, and which of those you actually need settles this long before capacity does.
Full profiles: BLUETTI AC500 + 2×B300K → · BLUETTI EP900 + 2×B500 →
Written by Gunner GustafsonUpdated
Whole-Home Backup Tester, Station Arena Test Desk
Spec deltas
The EP900 has no outlets. Not few, none: no sockets on the box, no USB, no 12V, no RV plug. Every watt it makes leaves through your breaker panel, which means it powers nothing at all until an electrician has wired it in. The AC500 + 2×B300K is the opposite animal, $3,948 of boxes with a 30A RV outlet, a 12V car port and 100W USB-C on the front, working the afternoon it lands on your driveway.
$10,298 buys 9,920Wh and 7,600W of continuous output against the AC500 stack's 5,530Wh and 5,000W. That's nearly 80% more energy and roughly half again the continuous output, plus 240V, a rated transfer no worse than 10ms, and 10 years of cover against 4. If the load you're backing up is a building, the EP900 is the buy and the rest of this page is about the one sentence that reverses it.
Here's that sentence. The AC500 stack clears every load on our scenario table on capacity, one of them barely, and it costs $6,350 less while asking nothing of your electrical panel. If your outage plan is a fridge, a freezer, a furnace blower, a router and some phones, you are not short of energy. You're short of a reason to spend the difference.
What the Numbers Reveal
Each conclusion stated first — the numbers behind it on one line, the full analysis below.
You're not buying a bigger battery here, you're buying your existing house back, including the 240V circuits the AC500 stack can't reach at any capacity. A well pump, an electric dryer and central air don't care how many watt-hours are sitting in the garage if there's no 240V outlet to plug them into, and there isn't one.
EP900 + 2×B500 record: AC 'Hardwired', 0 USB-A, 0 USB-C, 0 12V car, 0 30A RVAC500 + 2×B300K record: 30A RV outlet, 12V car port, 2 USB-A, 2 USB-C at 100WEP900 + 2×B500 carries 240V through the panel; AC500 + 2×B300K records no 240V outlet
Why it mattersIf your outage plan ends with 'and then I plug the fridge into the box', every advantage the EP900 has is on the far side of a panel tie-in you're never going to do, and the premium buys you wiring rather than watt-hours.
Cycle limits bind on a battery that gets cycled. A standby system that discharges during four outages a year isn't going to see 3,500 cycles, let alone the EP900's higher rating, so the cheaper lifetime kilowatt-hour is an accounting fact you never collect. The number only becomes money if something makes the battery work daily: solar self-consumption, or genuinely living off-grid.
Purchase cost per watt-hour: $.71 for the AC500 + 2×B300K, $1.04 for the EP900 + 2×B500Over the rated life, cost per kilowatt-hour delivered: 20 cents for the AC500 + 2×B300K, 17 cents for the EP900 + 2×B5003,500 rated cycles works out to 9.6 years of daily cycling and 33.7 years at weekend use
Why it mattersIf no panels are going on the roof, judge these two on today's price per watt-hour and ignore the lifetime figures entirely, which points at the AC500 stack.
solar input
The input ceiling, not the battery ceiling, is what caps the AC500 platform in a long outage. Hang another battery on it and the refill window gets longer, because 3,000W doesn't grow with the bank. The EP900's array headroom is already sized for a bank several times what it ships with: BLUETTI's own documentation runs the B500 ladder to roughly 39.6kWh across eight modulesB2.
Solar input ceiling: 9,000W on the EP900 + 2×B500, 3,000W on the AC500 + 2×B300KCapacity: 9,920Wh on the EP900 + 2×B500, 5,530Wh on the AC500 + 2×B300KBoth platforms accept additional BLUETTI batteries
Why it mattersAnyone planning to grow the system should be counting watts of input, not watt-hours of battery, because day three of an outage is decided by how fast you refill.
The specific dimensions that decide these two units — everything else is a tie.
Your Life, Your Pick
Selected because: Two of the six scenarios are a category error for both units, and the ones that aren't split cleanly: the blackout to the EP900, a van build to the AC500 stack by forfeit.
Read the winners column and you'll notice how little of it is about energy. Camping and the tailgate come back 'neither' for both units, and not because 2,100Wh is hard: it's that one of these is a pile of boxes you don't carry and the other is fastened beside your service panel. The CPAP night and the remote workday come back 'both', with either unit finishing barely dented. Capacity settles almost nothing in this matchup.
What the table does settle sits in two rows. The eight-hour blackout goes to the EP900 on depth, which only matters if your outages have a habit of running past bedtime. The van day goes to the AC500 stack by forfeit, because a panel-mounted system doesn't come along on a build, and then the AC500 stack nearly loses it on merit anyway. Those two rows are the actual fork: how long your worst outage runs, and whether the power has to travel.
Lifetime Value
Selected because: The EP900 costs more per watt-hour today ($1.04 against $.71) and less over its rated life, 17 cents a kilowatt-hour delivered against 20, and only frequent cycling collects the difference.
cost / lifetime kWh
The EP900 is the cheaper battery to own and the more expensive one to buy, and the gap between those two statements is where buyers get this wrong. Over its rated life it delivers roughly three times the lifetime energy of the AC500 stack, 59,520 kWh against 19,355 kWh, which is what drags its cost per kilowatt-hour below the AC500 stack's despite the bigger sticker.
That figure is a promise with a condition attached, and the condition is use. Lifetime energy is cycles multiplied by capacity, so a system that sits fully charged waiting for weather converts none of it. The buyer who genuinely collects the EP900's cost advantage is the one cycling it daily behind a solar array, not the one insuring against four storms a year. Work out how often this battery will actually be discharged before you let the per-kilowatt-hour line pick your unit.
What the Specs Don't Tell You
Selected because: Six cards fire here. Only the weight card lands on both units equally; the rest either lean to the EP900 or name something BLUETTI doesn't publish for the AC500 stack.
rated cycles
Stack the cards up and they point one way, with one loud exception. The EP900 takes the faster rated transfer, the longer term, the higher cycle rating and the only published noise figure in the matchup. The exception is that last one read backwards: BLUETTI publishes nothing for the AC500 stack, which isn't evidence it's louder, it's the absence of anything to hold it to. If the unit is going anywhere near a bedroom, you're buying on hearsay.
The weight card is the one that lands on both, and it lands differently on each. The EP900's 343 lbs is a single bad afternoon for whoever installs it and then irrelevant forever, because it never moves again. The AC500 stack's weight is spread across its boxes, so there's no brutal single lift, but there's also no version of it you reposition on a whim. Decide where it lives before it arrives, because that decision is effectively permanent for both.
Growth Path
Selected because: Both platforms take more batteries, but the AC500 stack's solar input tops out at 3,000W against the EP900's 9,000W, so its refill window stretches with every module you add.
solar input
Both units expand, and the brochure line that both expand is close to useless here. What differs is what happens to your recharge when you do. The AC500 platform's 3,000W solar ceiling is fixed, so every battery you add lengthens the time it takes to fill the stack from the sun. The EP900 accepts 9,000W, headroom that exists precisely because the B500 ladder is meant to climb.
That makes the growth question easier than it looks. If the system you'll own in three years is roughly the system you're buying now, the AC500 stack's ceiling never bites. If you're partway into a build that ends with a real array and a bank several times this size, the EP900 is the one that grows without getting slower to refill.
Strengths & trade-offs
BLUETTI AC500 + 2×B300K
Strengths
- +Costs $6,350 less
- +Lighter by 146.9 lb
Trade-offs
- –Weaker inverter (-2,600W) limits appliance compatibility.
- –Very heavy unit that may be difficult for one person to lift.
- –Shorter-lived battery — rated for 3,500 charge cycles vs the EP900 + 2×B500's 6,000, so it wears out sooner.
BLUETTI EP900 + 2×B500
Strengths
- +Larger battery capacity
- +Higher AC output
- +Longer warranty
- +Faster solar charging
- +Rated for 6,000 charge cycles — much longer battery lifespan
Trade-offs
- –Substantially more expensive (+$6,350) than the AC500 + 2×B300K.
- –Significantly heavier (+146.9 lbs), making it harder to move.
- –Very heavy unit that may be difficult for one person to lift.
Will It Power Your Gear?
Scenario math and per-appliance runtimes, modeled from the spec record.
Scenario verdicts
We ran the math on six real-world scenarios. Here's which unit survives your actual life.
SCN-01 · 2 nights · needs 2,100Wh
Weekend Camping
Two nights off-grid with essential comfort
Neither unit
Neither of these goes camping, and the capacity figures are a distraction from why. The AC500 stack is 196.1 lbs spread across its boxes, which rolls out of a truck bed if it travels at all, and the EP900 is fastened beside your breaker panel and stays there. The 2,100Wh a weekend asks for is nothing to either. The going is the problem, not the powering, so if you want power at a campsite, buy something with a handle.
Battery budget usedlower = more headroom
LOAD Phone Charger 15W×6h · LED Lights 40W×8h · Box Fan 75W×14h · CPAP Machine 40W×16h
SCN-02 · 8 hours · needs 1,645Wh
8-Hour Blackout
Keep the essentials running through a night without power
EP900 + 2×B500
Both get through the night. The question is the second night and the third. The EP900 finishes an eight-hour outage at 20% used, with roughly four more nights like it still in the bank, while the AC500 stack finishes at 35% with about two. If your outages are the summer-thunderstorm kind that end before bedtime, that spread buys you nothing at all. If the last one ran three days, it is the entire argument between these two.
Battery budget usedlower = more headroom
LOAD Fridge 150W×8h · Router + Modem 20W×8h · LED Lights (4 bulbs) 40W×6h · Phone Charger 15W×3h
SCN-03 · 8 hours · needs 320Wh
CPAP Overnight
Sleep therapy without interruption — the #1 medical use case
Either unit
Both cover a CPAP night on about 320Wh without noticing it, so capacity decides nothing and placement decides everything. The EP900 can't sit at your bedside, because it isn't something you place: it lives at the panel and its power reaches you through the wall socket, so the only published noise figure in this matchup belongs to the unit that was never going to be in the room. The AC500 stack is in the room, and BLUETTI publishes no figure for it. That's not proof it's loud. It's just nothing to hold it to at 3 a.m.
Battery budget usedlower = more headroom
LOAD CPAP Machine 40W×8h
SCN-04 · 8 hours · needs 910Wh
Remote Workday
Full work day off-grid without power anxiety
Either unit
Both run a full workday without strain, and the difference is where the cable goes. The AC500 stack lists 100W of USB-C, so the laptop charges straight off the battery. The EP900 has no USB at all, so the laptop charges from a wall socket like it always did, which is the point of a hardwired system: the power arrives in your room rather than out of a box on the floor.
Battery budget usedlower = more headroom
LOAD Laptop 60W×8h · External Monitor 30W×8h · Router + Modem 20W×8h · Phone Charger 15W×2h
SCN-05 · 4 hours · needs 670Wh
Tailgate Party
Game day power for the crew
Neither unit
Same answer as the campsite, for the same physical reason. The 670Wh and the 400W peak a tailgate asks for are trivial for both units. What a tailgate also asks is that the power turn up in a parking lot, and one of these is an installed appliance while the other is a stack you don't pick up. Neither wins because neither shows up.
Battery budget usedlower = more headroom
LOAD Blender 400W×0.5h · LED TV (55") 80W×4h · Bluetooth Speaker 15W×4h · Phone Charger (×3) 45W×2h
SCN-06 · 24 hours · needs 4,685Wh
Van Life Daily
A full day of mobile living — the ultimate endurance test
AC500 + 2×B300K
This row belongs to the AC500 stack by forfeit, since a panel-mounted system doesn't come along on a van build. Then it nearly loses on merit: 4,685Wh of daily draw against the 4,701Wh left after the flat 85% derate these scenarios apply leaves 16Wh at the end of the day. That isn't a reserve, it's a rounding error. One cloudy afternoon or one extra hour of the compressor and you're rationing, so take it, but specify your panels as though the battery were smaller than it is.
Battery budget usedlower = more headroom
LOAD Mini-Fridge 150W×24h · Laptop 60W×4h · Phone Charger 15W×3h · LED Lights 40W×5h · Fan 75W×8h
The Load Test
RUNTIME = (Wh × 0.85) ÷ LOAD
None of the scenarios above exactly yours? Build it. Toggle what you'd plug in; both units are tested against the combined draw.
Essentials
Comfort & Convenience
High-Draw Appliances
Test duration
8h
Continuous draw
205W
Projected runtime
For this load: EP900 + 2×B500 runs 41.1h vs 22.9h.
$10,298 list · direct from BLUETTI
Planning for more than this? Describe your whole setup and get it sized →
Modeled from the spec record — same math as the tables below. Methodology
Runtime by appliance
Real-world runtime estimates for common appliances, modeled at 85% inverter efficiency.¹
Essentials
The basics you need runningscale 0–562.1hComfort & Convenience
Makes off-grid life actually enjoyablescale 0–112.4hHigh-Draw Appliances
These reveal the real limitsscale 0–8.4h¹ Runtime = (capacity × 0.85) ÷ appliance watts. Within each group, all bars share one time scale (the group's longest runtime), so lengths are comparable across appliances; identical runtimes collapse into a single blue/orange bar. Actual runtime varies with battery age, temperature, and simultaneous loads — see methodology.
Conclusion
September 19, 2026
Verdict: the EP900 + 2×B500, on Power Score margin
Buy the EP900 + 2×B500 if the thing you're protecting is the house. It's the only one of the two that feeds a breaker panel, the only one carrying 240V, its transfer is the faster-rated of the pair, and it has a 10-year term behind it. The AC500 stack cannot be turned into that at any capacity, which is why this was never really a capacity comparison. Confidence sits at moderate rather than high because the EP900's case rests on two things this page can't decide for you: that you're paying an electrician, and that you'll cycle the battery often enough for its cycle rating to be money rather than trivia. Fail either one and the AC500 stack does the same practical work with sockets on the front, and leaves you the difference.
Today the AC500 + 2×B300K is $3,299, $649 under its typical $3,948. The verdict weighs typical prices, not today's. Prices checked 16 days ago.
Editor-assigned confidence, based on cited owner research and spec analysis.
List prices as of September 19, 2026. The links below open BLUETTI's current price.
$10,298.00 · direct from BLUETTI
Last checked 16 days ago. Prices move — check before you buy.
or check the AC500 + 2×B300K price$3,299.00 list
Written by Gunner Gustafson, Whole-Home Backup Tester · Station Arena Test Desk · Updated September 19, 2026
Black Friday · 38 days out
Prices to beat:AC500 + 2×B300K $3,299EP900 + 2×B500 $10,298
The lowest we have recorded for each. We have never seen the EP900 + 2×B500 discounted, so any real cut on it would be a first.
Measured Data
Benchmark scores and the full spec record, side by side.
Benchmark scores
Full specifications
ᵈ Derived: price ÷ rated capacity. See the data behind our comparisons →
Comparison ToolAdd more power stations, side by sideOpen Tool →How these numbers are produced
Numeric verification
Every figure on this page traces to our spec database or arithmetic on it — no estimated numbers.
Owner claims
Statements about owner experience are cited to published reviews — see Sources & Research Notes below.
Runtime model
Runtime = (rated capacity × 0.85 inverter efficiency) ÷ device wattage. Solar recharge estimates assume panels deliver 70% of rated output. Cold weather, battery age, and stacked loads reduce real-world results.
Power Score
Computed from 14 published spec dimensions, weighted per use-case bench. Higher is better; a unit must meet a bench's minimum threshold to be rated.
See the full weight table and data sourcing on our methodology page →Class ranking (the star rating)
Each unit's star score is a category ranking, not customer reviews — no buyer opinions feed it. We score every station on size-independent quality (value, output, portability, endurance, ports, warranty, and more), then percentile-rank it against the other units in its capacity class, so a class-leading compact unit and a class-leading whole-home unit can both earn 5★. Here, AC500 + 2×B300K rates 4.1/5 (47th percentile of 20 Home Backup-class units), and EP900 + 2×B500 rates 3.7/5 (21st percentile of 29 Whole-Home / Off-Grid-class units).
How the class ranking is computed →Test Notes & Caveats
Hidden gotchas and advantages we spotted that you won't find on the product page.
Weight Reality Check
Neither unit is grab-and-go. The AC500 + 2×B300K (196.1 lbs) is spread across its boxes — no single lift, but nothing you reposition on a whim. The EP900 + 2×B500 (343 lbs) is a wall-installed system — its weight matters to the installer on day one, then never again.
EP900 + 2×B500: 50dB Published
50dB is about as loud as moderate rainfall. It is BLUETTI's own rating rather than a reading on a shared bench — makers differ on whether they quote a best case or a figure under load, so treat it as a starting point rather than what you would hear at a bedside. For most people, fan noise around 45dB and up is where sleep starts to suffer.
AC500 + 2×B300K: Power Lifting to 6,000W
The AC500 + 2×B300K has BLUETTI's Power Lifting mode, which runs a resistive appliance rated up to 6,000W from its 5,000W inverter. It does that by delivering less power than the appliance asks for, not more than the inverter has: the heater still works, it just heats more slowly. Two things follow. BLUETTI scopes the mode to purely resistive loads — a heater, a kettle, an incandescent lamp — so it does nothing for a fridge compressor, a pump or a power tool; for motor loads the figure to read is the AC500 + 2×B300K's separate 10,000W surge peak, not this one. And it is not a reason to size down, because running a load that big from 5,530Wh is a short session either way. Genuinely useful if a heater or a kettle is why you're buying; beside the point otherwise. Our record for the EP900 + 2×B500 carries no Power Lifting figure, so check BLUETTI's own spec sheet before reading this as something the EP900 + 2×B500 lacks.
Transfer Speed: A Rating, Not a Stopwatch
Both figures are ceilings, so read them as classes rather than measurements: the EP900 is rated no worse than 10ms, the AC500 stack no worse than 20ms. The more useful difference isn't milliseconds, it's coverage. A UPS on the AC500 stack protects what you remembered to plug into the AC500 stack. The EP900 sits between the grid and your panel, so everything on the backed-up circuits rides through, including the things you'd never think to move onto a battery until the lights went out.
Ten Years Against Four, and Which Unit Needs It
The EP900 carries a 10-year term; the AC500 stack carries 4. Notice which unit the longer one is attached to. The AC500 stack is a set of boxes you can disconnect; the EP900 doesn't come off the wall without an electrician, so the cheaper failure to live with is the one on the shorter term. That's the right way round, but six extra years of cover on the harder unit to service is a real part of what the EP900 is selling, not a bonus stapled to the end of the spec sheet.
The Cycles Only Pay If You Spend Them
6,000 rated cycles against 3,500 is the EP900's strongest long-run number, and plenty of buyers will never collect a cent of it. At daily cycling those ratings work out to 16.4 years against 9.6; at weekend use you're into decades for both, and a battery that discharges during four outages a year won't approach either limit in your lifetime. The cycle advantage is real money for someone running solar self-consumption every day. For standby-only backup, it's a line in a spreadsheet you never get to cash.
AC500 + 2×B300K: Noise Level Not Disclosed
The EP900 + 2×B500 publishes its noise level (50dB); the AC500 + 2×B300K doesn't publish one. That isn't evidence the AC500 + 2×B300K is louder — it means there's no figure to hold it to, and no way to compare the two on this without hearing them. If you're buying for a bedroom, a CPAP, or an apartment, treat the EP900 + 2×B500's 50dB as the only published number on the table — a spec-sheet figure, not a measurement — and look for hands-on reports of the AC500 + 2×B300K before deciding.
Full record above — the Test Desk pick is the EP900 + 2×B500.
Check EP900 + 2×B500 price →or check the AC500 + 2×B300K priceOwnership Analysis
What happens after you buy — true cost of ownership, brand trust, and growth potential.
Lifetime value
Service lifeyears at one full cycle per day
Lifetime energy delivered
Cost per delivered kWh
│ warranty ends · Reaching the cycle rating means ~80% capacity remains — degraded, not dead.
Analyst note
The AC500 + 2×B300K is cheaper to buy, but the EP900 + 2×B500 is cheaper to own. At $0.17/kWh over its lifetime vs $0.20/kWh, the EP900 + 2×B500's higher cycle life and capacity make each dollar go further over the years.
Growth path
AC500 + 2×B300K
EXPANDABLESupports BLUETTI expansion batteries, so you can add capacity later without replacing the base unit — useful if your needs may climb past 5,530Wh.
Accepts up to 3,000W of solar. Enough for a serious multi-panel array.
Adequate ports for most setups, but heavy users may want a power strip.
Expansion batteries are BLUETTI-specific. You're investing in the BLUETTI ecosystem.
EP900 + 2×B500
EXPANDABLESupports BLUETTI expansion batteries, so you can add capacity later without replacing the base unit — useful if your needs may climb past 9,920Wh.
Accepts up to 9,000W of solar. Enough for a serious multi-panel array.
Limited ports. You'll likely need a power strip or splitter.
Expansion batteries are BLUETTI-specific. You're investing in the BLUETTI ecosystem.
Realistic full solar rechargeat 70% of rated panel output — see methodology
Analyst note
Both expand, but the EP900 + 2×B500's higher solar ceiling (9,000W vs 3,000W) gives it the stronger off-grid growth path — more panels can feed a bigger bank as it grows.
What Owners Report
Patterns from published owner reports and long-term reviews — every claim cited to its source below.
BLUETTI AC500 + 2×B300K
Start with what the field record can and can't tell you. Nobody has published on the exact two-battery stack, so every report here describes an AC500 running a single B300KA0. Same inverter, same battery model, so the fan, app, support and UPS findings carry across even though the runtime figures don't, and what carries across isn't all flattering. One review outfit reported that both units it tested, an AC300 and an AC500, powered up the battery but left the inverter deadA7. Another owner's unit shipped without the cable that connects the battery to the inverterA6. And there's no hard reset button to fall back on when something hangsA8.
The units that arrive working mostly stay working. One owner called his near-flawless from day one, with straightforward setup and a usable appA12; another is happy with his home-backup install and finds it quieter than a competing station he already ownsA1. The complaints are the kind you only collect by living with one: the fan is intermittent rather than constant, but you notice itA10, the indicator lights stay bright all night, which rules out the bedroomA11, the display gives you a percentage with no time-remaining or voltage readoutA2, and the battery has to be disconnected before the unit will power down, because the BMS keeps it awakeA4. One detail matters more than it sounds for a backup install: the same owner measured his pulling about 35 watts more from the grid than the load was actually using while passing power through, and put its standby overhead in the same range running as a UPSA3A5. On a system that sits online year-round, that's a slow meter.
“So far pretty darn happy, and it's much quieter than the small Pecron E1500LFP I have.”
Sources
firewoodhoardersclub.com · thesolarlab.com · freshlycharged.com · diysolarforum.com
BLUETTI EP900 + 2×B500
The EP900's field record is thin, and that's worth saying out loud rather than papering over. Our research turned up no long-term owner reports on the platform: what exists is maker and press material rather than people who have sat through outages with oneB0B1B2. The one owner-flavoured data point is a good one, a grid-to-battery transfer described as completely unnoticeable during an outageB3, but one account is one account. One more useful note from the same material: complete systems are quoted with installation excludedB4, which tells you where the real budget line hides. Buy this one on its specs and its warranty, not on a consensus that doesn't exist yet.
“A whole-home system: one EP900 inverter provides up to 9,000W (18,000W with two units), enough to run a washer, dryer, heater, and refrigerator.”
Sources
bluettipower.com · bestgeneratorsolar.com · mightygenerators.com · bgr.com · offgridsource.com
Sources & Research Notes
Every owner claim in this report is traceable to a published source. The bracketed references above resolve here.
Recurring owner themes
- Multiple sources report AC500 units arriving with hardware faults — a dead inverter or a missing battery-link cable — that required contacting Bluetti support. [AC500 + 2×B300K · 2 entries]
- Fan noise is intermittent but noticeable during charging/heavy load across sources, though one owner found it quieter than a competing unit. [AC500 + 2×B300K · 2 entries]
- The app covers the basics but owners want more detail (time-remaining, battery voltage), and the unit lacks a hard-reset option to recover from glitches. [AC500 + 2×B300K · 2 entries]
- Whole-home 9,000W output, large B500 expandability (to ~39.6kWh), 10ms UPS, and solar off-grid capability are the standout features. [EP900 + 2×B500 · 3 entries]
- A1
“So far pretty darn happy, and it's much quieter than the small Pecron E1500LFP I have.”
firewoodhoardersclub.com — jtakeman, "Bluetti AC500 w/B300K battery for our home backup/supplement system install and review" · 2025-02 · [positive]
- A2
“One other odd thing — it doesn't have a time-of-charge-remaining readout like my EF or Pecron units, just battery percentage. They don't even display battery voltage.”
firewoodhoardersclub.com — jtakeman, AC500 w/B300K install and review thread · 2025-02 · [negative]
- A3
“Only thing I see so far... when it switched to grid power it was drawing approximately 35 watts more than the actual usage.”
firewoodhoardersclub.com — jtakeman, AC500 w/B300K install and review thread · 2025-02 · [negative]
- A4
“Only drawback is it needs to be disconnected to shut the Bluetti unit down, as it keeps the BMS active and won't let it shut down.”
firewoodhoardersclub.com — jtakeman, AC500 w/B300K install and review thread · 2025-03 · [negative]
- A5
“Using about 31 watts an hour as a UPS — at 85% that should last about 8+ hours. Priceless!!”
firewoodhoardersclub.com — jtakeman, AC500 w/B300K install and review thread · 2025-03 · [positive]
- A6
“Got a hold of Bluetti support — seems they forgot to ship the cable connecting the main unit to the battery.”
firewoodhoardersclub.com — jtakeman, AC500 w/B300K install and review thread · 2025-02 · [negative]
- A7
“Both the AC300 and AC500 we tested had issues where the battery would turn on but not the inverter itself — dead on arrival, essentially.”
thesolarlab.com — Bluetti AC500 Review: Pros, Cons & the Ugly Truth · unknown · [negative]
- A8
“The lack of a hard reset button on these units is also really frustrating.”
thesolarlab.com — Bluetti AC500 Review: Pros, Cons & the Ugly Truth · unknown · [negative]
- A10
“The fan can get loud, though it's only intermittent and doesn't run constantly.”
freshlycharged.com — Powering A Room with Solar: Bluetti AC500 & B300K Review · unknown · [mixed]
- A11
“The indicator lights are quite bright and remain on all the time, so it's best not to keep the AC500 in a room where you'll be sleeping.”
freshlycharged.com — Powering A Room with Solar: Bluetti AC500 & B300K Review · unknown · [negative]
- A12
“Performed near flawlessly from day one, with easy-to-understand setup and a nice app for monitoring.”
diysolarforum.com — "Bluetti ac 500" owner thread · unknown · [positive]
- B1
“A whole-home system: one EP900 inverter provides up to 9,000W (18,000W with two units), enough to run a washer, dryer, heater, and refrigerator.”
bluettipower.com / bestgeneratorsolar.com — EP900 + B500 guide · 2026 · [positive]
- B2
“With B500 batteries (4,960Wh each), capacity expands from 9.9kWh up to about 39.6kWh with eight B500 modules — weeks of essential backup.”
bluettipower.com / mightygenerators.com — EP900 + B500 · 2026 · [positive]
- B3
“A fast UPS switches from grid to battery within 10 milliseconds; one owner reported the transfer is completely unnoticeable during outages.”
bgr.com / owner review — EP900 + B500 · 2026 · [positive]
- B4
“Built on reliable LiFePO4 cells; tied to solar, an owner said they can virtually go off-grid and minimize utility bills. Complete systems run roughly $14,500-$15,000 excluding installation.”
bgr.com / offgridsource.com — EP900 + B500 review · 2026 · [positive]
Research compiled September 19, 2026.
Who Should Buy Which
Buy the AC500 + 2×B300K if you…
- →You want the fridge, the freezer, the furnace blower and the router to ride out a storm, and you're not scheduling an electrician to arrange it. You plug things in. That's the whole install.
- →You're building a van or a rig. The AC500 stack is the only one of these two that travels at all, and it brings a 30A RV outlet and a 12V car port along. Size the solar generously, because the scenario table has it finishing a full van day on fumes.
- →You rent, you're in a condo, or the service panel simply isn't yours to modify. Every advantage the EP900 has lives on the other side of that panel.
- →You want to charge a laptop straight off the battery. The AC500 stack lists 100W of USB-C; the EP900 carries no USB at all.
Buy the EP900 + 2×B500 if you…
- →Your outage list includes a well pump, an electric dryer or central air. Those are 240V loads, and only the EP900 delivers 240V.
- →Real solar is going on the roof and the battery will cycle most days. The bigger input ceiling and the higher cycle rating are built for that life, and daily use is the only thing that turns the cheaper lifetime kilowatt-hour into money.
- →You want the outage to be invisible. A transfer rated no worse than 10ms sits between the grid and your panel, so the backed-up circuits ride through rather than just the one power strip you remembered to move.
- →You're keeping this in one house for the long haul. Ten years of cover on a wall-mounted system matches how long it will actually be hanging there.
If neither fits
If what you actually want is to take power somewhere, a campsite, a tailgate, a job site, close this tab with a clear conscience. The scenario table says 'neither' twice for exactly that reason: one of these you don't lift and the other you don't move. Buy a one or two kilowatt-hour unit with a handle on top, and put the savings toward a better cooler.
The Bottom Line
Take the EP900 + 2×B500 if the load you're protecting is a building. It's the only one here that feeds a breaker panel, the only one that carries 240V, and the wiring job isn't a cost bolted onto the product, it is the product. The AC500 stack is the cheaper battery per watt-hour, and you could keep hanging modules on it without ever getting there, because a 240V circuit doesn't care how many watt-hours are sitting in the garage.
And if that paragraph doesn't describe you, buy the AC500 stack and stop reading. No electrician, sockets on the front, 5,530Wh that clears every load on the table, for $6,350 less than the installed system. The EP900's cheaper lifetime energy is collected in cycles, and a battery waiting out four storms a year never spends them.
Frequently Asked Questions
Answers drawn from the spec record and cited owner research.
Can a BLUETTI AC500 with two B300K batteries back up my whole house?
Not in the sense the EP900 means it. The AC500 stack delivers its power through its own sockets, including a 30A RV outlet and a 12V car port, and it carries no 240V outlet, so the 240V circuits in your panel stay dark no matter how much battery you add. It will run a fridge, a freezer, a furnace blower and your electronics for a long time on 5,530Wh. Whole-house backup, where every protected circuit simply works, is the panel tie-in the EP900 is built around.
Does the BLUETTI EP900 need professional installation?
Yes. It's a hardwired system with no outlets of any kind on the unit, so until it's tied into your electrical panel it can't power a single thing. The material we found on it quotes installation separately from the hardware, which is the honest way to read the price tag: the number on the product page is not the number to budget. If hiring an electrician is off the table, this comparison ends here and you want the AC500 stack.
Is the EP900 + 2×B500 worth $6,350 more than the AC500 stack?
If you're buying 240V backup or daily solar cycling, yes. If you're buying insurance against the occasional outage, no. The EP900 works out cheaper per kilowatt-hour across its rated life, 17 cents against 20, but that arithmetic assumes thousands of real cycles, and a battery that discharges four times a year never gets near them. At that usage you've paid the premium for durability you won't live long enough to use. The split here is behavioural, not technical.
Which is quieter, the AC500 or the EP900?
On paper the EP900, because it publishes 50dB and BLUETTI publishes nothing for the AC500 stack. Treat that as a spec-sheet figure rather than a measurement, and treat the silence on the other side as a missing number rather than a bad one. In practice placement answers the question: the EP900 is installed at your panel, while the AC500 stack sits in whichever room you put it in, where owners report an intermittent but audible fan and indicator lights that stay bright all night. For a bedroom, that last detail outweighs either number.
Can I add more batteries to either system later?
Both take more batteries; only one keeps up with the sun as you do. The AC500 platform's solar input is capped at 3,000W however much battery you hang on it, so each added module lengthens the time a full refill takes. The EP900 accepts 9,000W, and BLUETTI's own documentation runs the B500 ladder out to roughly 39.6kWh across eight modules. If growth is the plan, count the input ceiling rather than the battery ceiling.
Where to buy
BLUETTI AC500 + 2×B300K
$3,299.00
$3,299.00 · direct from BLUETTI
down from $3,948 · 16% below usual
Last checked 16 days ago. Prices move — check before you buy.
BLUETTI EP900 + 2×B500Pick
$10,298.00
$10,298.00 · direct from BLUETTI
Last checked 16 days ago. Prices move — check before you buy.
Prices may vary by retailer and are subject to change.