Head-to-head test
EcoFlow DELTA Pro Ultra + 2 Batteries vs BLUETTI EP900 + 3×B500
Both are whole-home batteries, but only one is still a machine you can plug into: the EP900 does nothing until an electrician finishes, while the DELTA Pro Ultra works the day it lands and holds 3,552Wh more for $5,799 less.
Full profiles: EcoFlow DELTA Pro Ultra + 2 Batteries → · BLUETTI EP900 + 3×B500 →
Written by Gunner GustafsonUpdated
Whole-Home Backup Tester, Station Arena Test Desk
Spec deltas
The cheaper system here is also the larger one: 18,432Wh against the EP900's 14,880Wh, for $5,799 less. That inversion is most of the verdict, and the rest of this page is the EP900 trying to earn the difference back.
It has three honest ways to try. It is rated for 6,000 cycles against 3,500, it accepts 9,000W of solar against 5,600W, and its inverter runs 1,800W higher continuous at 9,000W. None of those are marketing. For one specific buyer they decide the whole matchup.
The thing to understand first is that you are not choosing a box, you are choosing an installation. The EP900 is hardwired: no AC outlets, no USB, nothing on it you can plug into, so it becomes a power source only after an installer ties it into your panel and picks which circuits it protects. The Ultra can be wired in the same way, and can also sit in the garage running loads through its own sockets while you wait for that appointment. Unless your plan is to cycle the pack nightly on a big array, buy the EcoFlow.
What the Numbers Reveal
Each conclusion stated first — the numbers behind it on one line, the full analysis below.
rated cycles
So the EP900's extra 2,500 cycles (6,000 minus 3,500) are not a general advantage, they are a specific one, and they belong to the house that cycles the pack every night on solar or time-of-use rates. That buyer is really purchasing one installation instead of two, because the replacement at year 9.6 of daily cycling is not a box arriving on a pallet, it is another electrician on another ladder.
EP900 + 3 batteries: 6,000 rated cycles. DELTA Pro Ultra + 2 Batteries: 3,500At daily cycling that works out to 16.4 years against 9.6At twice-a-week use it works out to 57.7 years against 33.7Both carry a 10-year warranty
Why it mattersIf the system's job is to wait for storms, buy watt-hours and stop paying for cycles. If it will run your evenings, the EP900's extra years are the strongest case on this page for spending $5,799 more.
The Ultra does the same whole-home job through a panel when you want it to, and it also works the afternoon it is delivered. Even that install is not trivial: the reviewer who wired one in struggled to find an electrician who had seen the gearA16, and the job ran nine hours with drywall cut out to sink the panelA17. One of these is a purchase. The other is a project, and the project cannot start until somebody else's calendar allows it.
EP900 record: AC listed as Hardwired, 240V as Hardwired, zero USB-A, zero USB-C, no 30A RV outletDELTA Pro Ultra + 2 Batteries: 3 AC outlets, two 240V outlets, one 30A RV outlet, 2 USB-C ports at 100WThe Ultra's record reads hardwired: no. The EP900's reads hardwired: yes
Why it mattersIf your install date is uncertain, or you might not own this house in ten years, that gap matters more than any row in the spec table.
solar input
Day one belongs to the bigger reservoir. Day four belongs to the faster refill. Which of those you are buying depends on a number that is not on this page: how many panels are on your roof. A 9,000W input ceiling behind a small array is a wider funnel on the same hose, and it costs $5,799.
Usable energy after the flat 85% derate: 15,667Wh for the Ultra, 12,648Wh for the EP900Solar input ceilings: 5,600W for the Ultra, 9,000W for the EP900From empty at full rated input: 18,432Wh divided by 5,600W is about 3.3 hours, 14,880Wh divided by 9,000W about 1.7
Why it mattersBuy the EP900's input ceiling only if the array to feed it exists or is already budgeted. Otherwise the extra capacity is the part of this comparison you will actually use.
continuous output
That turns the output column upside down. The EP900 is the stronger sustained inverter by 1,800W, and the Ultra is the one with documented starting margin, which is the thing people are actually worried about when they read this column. Startup surge is why a house full of motors trips an inverter that survives the same load all afternoon.
Continuous output: 9,000W for the EP900, 7,200W for the UltraThe Ultra publishes a 10,800W peak, which is 3,600W of headroom over its own continuous ratingOur record carries no published peak for the EP900A reviewer ran a central air conditioner, a refrigerator and a well pump simultaneously on a DELTA Pro UltraA9
Why it mattersIf the question is whether the central AC restarts on battery, the published headroom belongs to the Ultra. If it is whether a heavy 240V load runs for hours, the EP900 has the bigger inverter.
The specific dimensions that decide these two units — everything else is a tie.
Lifetime Value
Selected because: $5,799 separates them and the cheaper system is the bigger one, 18,432Wh against 14,880Wh, with the EP900's 6,000 cycles against 3,500 as the counter-argument.
cost / lifetime kWh
Twelve cents a kilowatt-hour against fifteen. That is the whole ownership argument, and the Ultra wins it despite having the shorter-lived pack, because it is cheaper by $5,799 and holds more energy per cycle. The EP900 answers with total volume: 89,280 kWh of lifetime energy against 64,512, which is 24,768 kWh more electricity over the life of the hardware.
Here is the honest catch in our own pick's favour and against it at once. The Ultra's cheaper kilowatt-hour quietly assumes you are willing to buy a second system when the first one reaches its cycle limit, and on a daily-cycling house that arrives at 9.6 years against the EP900's 16.4. A replacement battery is a purchase. A replacement installation is a purchase plus an electrician plus a day of your house being a construction site. Weigh that against the per-kilowatt-hour figure before you treat it as settled.
Your Life, Your Pick
Selected because: Two of the six rows come back as neither, because neither of these systems travels, and reading the table any other way will mislead you.
Read this table sideways. Every row passes for both units, and the percentages are almost comically small: a CPAP takes 2% of the Ultra's usable energy and 3% of the EP900's, a full remote workday takes 6% and 7%. Capacity is not the question anywhere in this comparison, because both of these systems are sized for a house and the table is sized for a weekend.
The two rows that return neither are the informative ones. At 405.4 lbs across a stack of boxes and 466 lbs bolted to a wall, no camping trip and no tailgate is happening, and the EP900 has no outlet to plug a cooler into even if you could get it there. What the table really demonstrates is that the decision between these two is not about running any single load. It is about where the power comes out, how fast it goes back in, and how many years the hardware has in it.
Growth Path
Selected because: Both accept expansion batteries, so the only ceiling that genuinely differs is solar input: 9,000W on the EP900 against 5,600W on the Ultra.
solar input
Both accept more batteries, so expansion capacity is a wash and the interesting ceiling is the one over your head. The EP900 takes 9,000W of solar against the Ultra's 5,600W, which is 3,400W more roof, and it is the single specification in this comparison you cannot reach by any other route. Add batteries to either system and the EP900 is still the one that can charge a growing bank in a morning.
The catch is that the roof decides, not the inverter. A solar ceiling is a permission, not a capability, and it delivers nothing until the panels exist to reach it. If your array is already large, or the quote is signed, this is the number that makes the EP900 the right system. If solar is a someday plan, you are paying now for capability you will unlock later, at a price of $5,799 with 3,552Wh less storage in the meantime.
What the Specs Don't Tell You
Selected because: The cards that fire here (weight, UPS class, cycle life) are the ones that decide an installed system, and one of them argues against our pick.
rated cycles
The weight card is the least useful thing on this page, because neither of these is going anywhere: 405.4 lbs and 466 lbs are installation figures, not portability figures. What matters is the shape of the weight. The Ultra's sits in a stack of boxes on a floor, which means it can be broken down and taken to your next house. The EP900's lands on the installer once and then stays on that wall permanently, which is the point of it.
The two cards worth reading closely are UPS class and cycle life, and they split. Neither switchover figure is a measurement: the Ultra's record carries a published 0, which is EcoFlow classifying the design as no-break rather than a stopwatch result, and the EP900's 10ms rating is the same kind of claim from a different maker. Owners running two-battery Ultra systems do describe the transfer as invisible in practice, with no flicker when the grid dropsA9A14. Cycle life is the reverse, and it is the strongest card the unit we did not pick holds.
Brand Trust
Selected because: A 10-year warranty on a battery wired into your house is a 10-year bet on the company's support desk.
Both of these carry a 10-year warranty, which means the real question is not the paperwork but who answers when you call in year seven. EcoFlow gives you a US phone line and outcomes that split hard, plus a policy worth knowing before you spend this much: no parts and no service offered out of warranty. BLUETTI's support is the most inconsistent in the category, heavily email-based across a wide timezone gap, and buying direct rather than through a reseller tends to produce better support outcomes.
The field reports mirror that split in a way that should give both camps pause. EcoFlow owners describe support answering technical questions by pointing back at the web guide that prompted them, twice, and suggesting a faraday cage for radio interferenceA2A4A5. On the BLUETTI side the pattern is stranger, because it is mostly anticipatory: prospective buyers keep saying the spec sheet reads like a dream and the support reputation is the reason they hesitateB1B2. Neither company has earned a decade of trust on this evidence. Buy from a retailer with a real returns desk and register the warranty the day it is installed.
Strengths & trade-offs
EcoFlow DELTA Pro Ultra + 2 Batteries
Strengths
- +Costs $5,799 less
- +Lighter by 60.6 lb
- +Larger battery capacity
Trade-offs
- –Weaker inverter (-1,800W) 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 + 3×B500's 6,000, so it wears out sooner.
BLUETTI EP900 + 3×B500
Strengths
- +Higher AC output
- +Faster solar charging
- +Rated for 6,000 charge cycles — much longer battery lifespan
Trade-offs
- –Substantially more expensive (+$5,799) than the DELTA Pro Ultra + 2 Batteries.
- –Significantly heavier (+60.6 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. One is a 405.4 lb stack of boxes and the other is bolted to your electrical panel, so the 2,100Wh this weekend needs is beside the point. Both hold it many times over and neither is coming with you. If camping is why you are shopping, you are in the wrong class of product entirely.
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
Either unit
Eight hours barely registers for either: the load takes 10% of the Ultra's usable energy and 13% of the EP900's. Both list a UPS mode, the Ultra rated as a no-break design and the EP900 at 10ms, though both are maker classifications rather than stopwatch results. The blackout that actually separates them is the four-day one, where refill speed decides it: 9,000W of solar input against 5,600W, if you own the panels to fill it.
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
A CPAP takes 2% of the Ultra's usable energy and 3% of the EP900's, so capacity is a formality here and the published noise ratings come from two makers measuring their own way. What settles this row is simpler. The Ultra has sockets, so a CPAP plugs into it the day it arrives. The EP900 has none, and feeds your house wiring instead, so the outlet beside your bed only works once an installer has put that circuit on the backup panel.
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 working day without noticing: 910Wh is 6% of the Ultra's usable energy and 7% of the EP900's. The difference shows up at the desk. The Ultra puts 100W of USB-C on the box, so the laptop skips the inverter entirely, while the EP900 carries no USB at all because a hardwired system's outlets are the ones already in your wall.
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
Nothing here belongs in a parking lot. The 670Wh and the 400W peak are trivial for both, but the EP900 has no outlet to plug anything into and the Ultra's 405.4 lbs is a loading-dock problem. The useful question for either of these is what is happening back at the house while you are out.
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
DELTA Pro Ultra + 2 Batteries
This row goes to the Ultra by forfeit, since the EP900 is installed at a building's panel and does not travel, but it is not an empty win: the Ultra covers the 4,685Wh day and still has 10,982Wh of usable energy in the bank. The honest caveat is that 405.4 lbs is a chassis decision rather than a van accessory. You would be building the van around it.
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: DELTA Pro Ultra + 2 Batteries runs 76.4h vs 61.7h.
$7,999 list · direct from EcoFlow
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 0–1044.5hComfort & Convenience
Makes off-grid life actually enjoyablescale 0–208.9hHigh-Draw Appliances
These reveal the real limitsscale 0–15.7h¹ 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 DELTA Pro Ultra + 2 Batteries
Take the DELTA Pro Ultra stack. It holds more energy (18,432Wh against 14,880Wh), costs $5,799 less, and delivers its lifetime energy at about 12 cents a kilowatt-hour against 15. It also arrives usable: three AC outlets, two 240V outlets, a 30A RV plug and 100W of USB-C mean it runs loads on day one and gets wired into the panel whenever your electrician has a slot. The EP900 is the better machine on three specific counts, all of which point at one buyer: 6,000 cycles against 3,500, a 9,000W solar input ceiling against 5,600W, and 1,800W more continuous inverter. If you are going to cycle the pack every night on a large rooftop array, those add up to one installation instead of two and the EP900 is worth its premium. If the system's job is to sit at full charge waiting for outages, you would be paying $5,799 for cycles you will never spend and solar input you cannot feed.
Editor-assigned confidence, based on cited owner research and spec analysis.
List prices as of September 19, 2026. The links below open EcoFlow's and BLUETTI's current prices.
$7,999.00 · direct from EcoFlow
Last checked 16 days ago. Prices move — check before you buy.
or check the EP900 + 3×B500 price$13,798.00 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:DELTA Pro Ultra + 2 Batteries $7,899EP900 + 3×B500 $13,798
The lowest we have recorded for each. We have never seen the EP900 + 3×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, DELTA Pro Ultra + 2 Batteries rates 3.8/5 (29th percentile of 29 Whole-Home / Off-Grid-class units), and EP900 + 3×B500 rates 4.2/5 (54th 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.
Neither of these gets carried
405.4 lbs and 466 lbs are installation figures, not portability figures, so the interesting thing is the shape of the weight rather than the total. The Ultra's is spread across a stack of boxes standing on a floor, which means it can be broken down and taken to the next house. The EP900's lands on the installer once, on the wall, and then stops mattering, because it is never coming off that wall.
EP900 + 3×B500: 50dB Published
50dB is about as loud as moderate rainfall. The DELTA Pro Ultra + 2 Batteries is rated 30dB — lower, but published by a different maker measuring its own way, so the two figures are not a like-for-like gap. For most people, fan noise around 45dB and up is where sleep starts to suffer.
Two ratings, neither of them a measurement
The Ultra's record carries a published 0, which is EcoFlow classifying the design as no-break rather than a stopwatch result, and it should be read as a class rather than a time. The EP900's 10ms is the same kind of claim from a different maker, quick enough on paper that a desktop with unsaved work rides through. The part no switchover rating covers: on the EP900, only the circuits your installer moves onto the backup panel are protected at all.
Warranty: No Difference
Both units carry the same 10-year warranty, so coverage isn't a tiebreaker here. Worth saying because the per-dollar framing can suggest otherwise: the DELTA Pro Ultra + 2 Batteries works out at 1.3 years of cover per $1,000 spent against the EP900 + 3×B500's 0.7, but that spread is the price gap, not the terms.
The pack we picked is the shorter-lived one
6,000 cycles against 3,500 is the EP900's best argument and it is a real one. Cycled daily, that is 16.4 years against 9.6, which is the difference between one installation and two. But cycles only count if you spend them: at twice-a-week use the same ratings come out at 57.7 years against 33.7, which is a roundabout way of saying the battery is not what fails first. Whether this card decides your purchase depends entirely on how often the pack gets emptied.
Full record above — the Test Desk pick is the DELTA Pro Ultra + 2 Batteries.
Check DELTA Pro Ultra + 2 Batteries price →or check the EP900 + 3×B500 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
Both units have similar long-term ownership costs ($0.12/kWh vs $0.15/kWh). The price difference is what you see on the sticker — neither is a hidden bargain or rip-off.
Brand trust
EcoFlow
Ecosystem
Largest in portable power — 12-15 models across DELTA Pro, DELTA 3, and RIVER 3 series, plus solar panels and smart home panels
Support
US-based phone/email/chat support (1-800-368-8604). Experiences are polarized — many report hassle-free prepaid-label replacements, but others report long waits and refurbished units sent for new claims. Pro tip: buying from Costco or Amazon gives you a stronger return safety net.
Community
Largest community in the space — Reddit r/Ecoflow_community (~31K members), multiple Facebook groups, and an official community forum
App experience
Rated 4.6/5 iOS (~8,400 ratings) · 4.2/5 Android (~17,000 ratings)
Unique strength
Fastest-charging technology (X-Stream), deepest product ecosystem, and most active innovation cadence. At the top of the range sit two whole-home paths: the TITAN line, one 5 kWh unit that grows to 30 kWh, and the DELTA Pro Ultra platform, which stacks batteries and inverters further — flagship paths, not line-wide features.
Worth knowing
EcoFlow's out-of-warranty policy is the fine print that matters on a system meant to last a decade: no parts and no service once cover ends. The support experiences split hard, with plenty of hassle-free prepaid-label replacements alongside long waits and refurbished units sent against new claims, so buying through a retailer with a genuine returns desk is cheap insurance.
BLUETTI
Ecosystem
One of the broadest lineups — 15-20+ models from budget (AC2A) to flagship portable (Apex 300, 2764.8Wh). Includes specialized products: vehicle solar hubs, sodium-ion cold-weather units, and balcony storage systems.
Support
The most inconsistent support in the space. Heavily email-based with China timezone delays. Some users get smooth, efficient service; others report weeks of troubleshooting runarounds, being offered discounts on new units instead of repairs, and confusing third-party purchase claim processes. Buying direct from Bluetti's website tends to produce better support outcomes.
Community
Active and growing — Reddit r/bluetti has a dedicated community. Second-largest after EcoFlow in engagement.
App experience
Rated 4.5/5 iOS and Android — tied for best app experience in the category. V3.0 UI redesign was well-received.
Unique strength
Among the best capacity-to-price ratios available — several Elite and Apex units are the lowest $/Wh in the catalog. Widest product diversity including industry-firsts like sodium-ion cold-weather units and dual solar+alternator vehicle hubs. LFP across the rest of the range, though rated cycle life spans 2,500 (EB3A) to 6,000, and it varies WITHIN the Elite range rather than tracking it — the Elite 300 and Elite 200 V2 are rated 6,000 while the Elite 30 V2, Elite 10 Mini, Elite 320 and Elite 400 are rated 3,000+ and the Elite 100 V2 4,000+, so check the specific model. Dual-voltage (120V/240V) in flagships.
Worth knowing
BLUETTI's support is the most inconsistent in the category, mostly email and mostly across a wide timezone gap, and buying direct rather than through a reseller is what most reliably improves the outcome. On a system that is wired into your house, that is not a minor operational detail.
Analyst note
Both companies are asking you to trust them for ten years with something bolted into your electrical system, and neither support record makes that comfortable. EcoFlow gives you a US phone line, the largest community in the category for when the phone line fails you, and a firm no-service-after-warranty policy. BLUETTI's usual advantage is capacity per dollar, and this is the one matchup where it does not have it.
Growth path
DELTA Pro Ultra + 2 Batteries
EXPANDABLESupports EcoFlow expansion batteries, so you can add capacity later without replacing the base unit — useful if your needs may climb past 18,432Wh.
Accepts up to 5,600W 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 EcoFlow-specific. You're investing in the EcoFlow ecosystem.
EP900 + 3×B500
EXPANDABLESupports BLUETTI expansion batteries, so you can add capacity later without replacing the base unit — useful if your needs may climb past 14,880Wh.
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 + 3×B500's higher solar ceiling (9,000W vs 5,600W) 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.
EcoFlow DELTA Pro Ultra + 2 Batteries
Field reports on this exact three-box configuration are thin, and the strongest of them come from one detailed forum thread plus a handful of short retailer reviews, several of which say outright that it is too early to speak to longevityA0. What exists splits cleanly. Owners with two-battery setups describe the system doing the whole-home job it is sold for: a reviewer ran a central air conditioner, a refrigerator and a well pump at once without a stumbleA9, one owner reports it running most of the house with no flicker at the transferA14, and another says the second battery doubled real runtime and removed the anxiety during peak hoursA13. One owner runs two of these systems and rates the thermal management in temperature extremes as a genuine strengthA10.
The complaints cluster just as tightly, and most of them are about the company rather than the hardware. Support pointed an owner at the web guide he was complaining about, twiceA2, suggested a faraday cage when he reported the inverter interfering with common radio frequenciesA3A4, and twice sent him to an app screen that does not contain the state-of-charge chart he asked forA5. One owner watched a pack charged to 90% fall to 8% over a few daysA6, and a reviewer flags the system's idle self-consumption as something you must budget for in off-grid use rather than ignoreA7. Two practical notes for anyone planning the install: the extra battery is a two-person liftA8, and one owner found the battery nearest the inverter running consistently warmer than the one below it, in a garage that gets genuinely hot in summerA11A12.
“This means that without any grid or solar input, the system would fully drain its own 6kWh battery in about 60 hours. For off-grid use, this parasitic drain must be carefully factored into your energy budget.”
BLUETTI EP900 + 3×B500
The EP900 ledger is thinner still and mostly pre-purchase, which is what happens with an expensive niche home system rather than a portable boxB0. There is a confirmed owner running one in Costa RicaB10, and an appreciation of the hardware that reads like it comes from people who install things: the inter-battery cabling finally does not stick a foot out of the wallB4, and the heavy-duty DC disconnect, rather than a button or switch, is expected to age betterB9. The outdoor-capable enclosure is called out as a real advantageB5, followed immediately by skepticism about how it behaves in genuine heat or a run of sunless winter daysB6, and about what the system quietly consumes on its ownB7. Both of those last points are forum reasoning, not measurement.
What dominates this ledger is a worry rather than an experience. Prospective buyers keep saying the same thing: the specification looks excellent and BLUETTI's support record is the reason they have not pulled the triggerB1B2. The corroborating complaints we found, a warranty unit that stopped charging and a buyer who could only reach support through a website chat widget, could not be tied to this modelB11B12, and the one positive account of fast email support is attached to a different BLUETTI unitB3. Treat all three as brand character, not EP900 evidence. Nobody has yet published a long-term account of living with this system.
“on paper it's a dream but who knows with Bluetti tech support?”
Sources
diysolarforum.com · lifenhancer.com · bluettipower.worthepenny.co · trustpilot.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
- Owners repeatedly report EcoFlow customer support gives dismissive or unhelpful answers to specific technical questions (manual gaps, RFI interference, app charting). [DELTA Pro Ultra + 2 Batteries · 3 entries]
- The unit's idle/parasitic self-consumption is a recurring theme, both as a documented SoC anomaly and as an acknowledged spec-level drain figure from a tester. [DELTA Pro Ultra + 2 Batteries · 2 entries]
- Multiple owners note the extra battery packs are extremely heavy (100+ lbs each), requiring two people, and one owner separately observed uneven heat between stacked batteries raising summer overheating concerns. [DELTA Pro Ultra + 2 Batteries · 3 entries]
- Real owners with 2-battery setups consistently praise seamless/flicker-free UPS switchover and confirm the system genuinely runs whole-home loads (AC, well pump, most of house). [DELTA Pro Ultra + 2 Batteries · 3 entries]
- Adding a second battery is described by owners as meaningfully extending real-world runtime for whole-home backup, matching expectations. [DELTA Pro Ultra + 2 Batteries · 2 entries]
- Prospective buyers repeatedly cite fear of poor Bluetti customer service/support as a deciding concern before purchase, and general Bluetti-brand reviews (not EP900-specific) corroborate slow or unhelpful support experiences. [EP900 + 3×B500 · 4 entries]
- Owners/installers praise the physical build quality improvements over older Bluetti units — cleaner cable management and a heavy-duty DC disconnect instead of a simple switch. [EP900 + 3×B500 · 2 entries]
- Skepticism exists about outdoor-enclosure durability claims in extreme heat/cold and about the unit's own parasitic power consumption, though this comes from forum speculation rather than confirmed field testing. [EP900 + 3×B500 · 2 entries]
- A2
“No real manual. All they have is the web user guide which is superficial if I'm being generous. I asked support about it and they pointed me at the web guide I was complaining about. Twice.”
DIY Solar Power Forum — 'Ecoflow Delta Pro Ultra issues' thread · 2024-02 · [negative]
- A3
“Even when the inverter is not running, it interferes with common frequencies like 146.520MHz.”
DIY Solar Power Forum — 'Ecoflow Delta Pro Ultra issues' thread · 2024-02 · [negative]
- A4
“I contacted EcoFlow support and they told me I could put it in a 'faraday cage'.”
DIY Solar Power Forum — 'Ecoflow Delta Pro Ultra issues' thread · 2024-02 · [negative]
- A5
“No State of Charge graph in the app... I contacted support and twice they told me to go to the app screen with the charts, which only has input and output.”
DIY Solar Power Forum — 'Ecoflow Delta Pro Ultra issues' thread · 2024-02 · [negative]
- A6
“After a few days of using it overnight and letting it charge back up to '90%', it'd go from '90%' down to '8%'.”
DIY Solar Power Forum — 'Ecoflow Delta Pro Ultra issues' thread · 2024-02 · [negative]
- A7
“This means that without any grid or solar input, the system would fully drain its own 6kWh battery in about 60 hours. For off-grid use, this parasitic drain must be carefully factored into your energy budget.”
Battery Skills — 'EF ECOFLOW DELTA Pro Ultra + Extra Battery Review' · 2025-10 · [mixed]
- A8
“The main inverter is a manageable 71 lbs, but each Ultra Smart Extra Battery is a dense 115 lbs, requiring two people for safe movement.”
Battery Skills — 'EF ECOFLOW DELTA Pro Ultra + Extra Battery Review' · 2025-10 · [mixed]
- A9
“We powered a central air conditioner, refrigerator, and well pump simultaneously without a flicker.”
Battery Skills — 'EF ECOFLOW DELTA Pro Ultra + Extra Battery Review' · 2025-10 · [positive]
- A10
“I own two Delta Pro Ultra's with two batteries each... We have experienced matchless performance, scalability, flexibility. It cools/heats itself in temperature extremes-simply awesome!”
Walmart customer reviews — 'EF EcoFlow Extra Battery for DELTA Pro Ultra' · unknown · [positive]
- A11
“I noticed the battery closest to the inverter seems to run hotter than the one below. About 10 degrees warmer. I switched the batteries around to ensure that it wasn't the battery and got the same results.”
Walmart customer reviews — 'EF EcoFlow Extra Battery for DELTA Pro Ultra' · unknown · [negative]
- A12
“My garage could get up to 98 degrees during the summer, that means my batteries can overheat.”
Walmart customer reviews — 'EF EcoFlow Extra Battery for DELTA Pro Ultra' · unknown · [negative]
- A13
“I originally bought my Delta Pro Ultra with the single battery, worked great is able to power my entire home for about 4 to 5 hours during peak times... I bought a second battery... My run time has doubled eliminating the anxiety.”
Walmart customer reviews — 'EF EcoFlow Extra Battery for DELTA Pro Ultra' · unknown · [positive]
- A14
“With the home panel, there is no flicker when the power changes. I bought a unit with 2 batteries and it runs my most of my house.”
Walmart customer reviews — 'EF EcoFlow Extra Battery for DELTA Pro Ultra' · unknown · [positive]
- A16
“In my neck of the woods (suburban Detroit), it was a bit challenging finding one who had experience with this kind of gear.”
Yahoo Tech — 'EcoFlow Delta Pro Ultra whole home battery backup review' · 2024-06 · [mixed]
- A17
“Sure enough, the job went smoothly; it took him around nine total hours to complete, which included cutting out portions of drywall in order to sink the panel into the wall.”
Yahoo Tech — 'EcoFlow Delta Pro Ultra whole home battery backup review' · 2024-06 · [mixed]
- B1
“on paper it's a dream but who knows with Bluetti tech support?”
diysolarforum.com — Bluetti EP900 thread · 2023-04 · [mixed]
- B2
“We are looking into adding a home battery backup, specifically the EP900 with 3 B500 batteries. The cost seems really competitive, but I'm concerned about some very negative customer service reviews.”
diysolarforum.com — Bluetti EP900 thread · 2023-04 · [mixed]
- B3
“customer service for EP800/900 ESS can be reached directly through this number... Their email support is also very responsive, and last time it took less than 24 hours to resolve a firmware issue with my AC500.”
diysolarforum.com — Bluetti EP900 thread · 2023-04 · [positive]
- B4
“Nice that Bluetti finally came up with a battery cable system between it's batteries that isn't a giant bulky obtrusive cable sticking a foot out.”
diysolarforum.com — Bluetti EP900 to Power your House thread · 2023-04 · [positive]
- B5
“The one thing nice about this EP900 is they sell an enclosure and it can be kept outdoors.”
diysolarforum.com — Bluetti EP900 to Power your House thread · 2023-04 · [positive]
- B6
“Sunshine on it, it'll get hot... if you need to use it in real heat, or real cold for a string of near solar-less winter days I wouldn't count on it if it's installed outside.”
diysolarforum.com — Bluetti EP900 to Power your House thread · 2023-04 · [negative]
- B7
“Imho, Bluetti marketing is quite unrealistic. I wonder what the units consume themselves.”
diysolarforum.com — Bluetti EP900 to Power your House thread · 2023-04 · [negative]
- B9
“I really like that there's a heavy-duty DC disconnect on these units rather than a button or switch. This will be much more reliable long term.”
lifenhancer.com — Bluetti EP900 Review · 2025-03 · [positive]
- B10
“Bought the EP900 + 3×B500 for our home in Costa Rica.”
lifenhancer.com — Bluetti EP900 Review (reader comment referenced in review) · 2025-03 · [positive]
- B11
“I've had one of the worst experiences with customer service ever. My power station stopped charging, and since it was still under warranty, I reached out to the company.”
bluettipower.worthepenny.com — Bluetti Power customer review aggregator · unknown · [negative]
- B12
“Customer service is difficult to reach, only via a chat app on the website, and they are unable to assist you further.”
trustpilot.com — Bluetti reviews · 2025 (approx.) · [negative]
Research compiled September 19, 2026.
Who Should Buy Which
Buy the DELTA Pro Ultra + 2 Batteries if you…
- →You want the house covered before the next storm season and your electrician is booked into next year. The Ultra runs loads off its own sockets the day it arrives, three AC outlets, two 240V and a 30A RV plug, and gets tied into the panel whenever that appointment finally happens.
- →You are backing up a house you may not own in a decade. It stacks on the garage floor rather than bolting to the wall, so it moves with you instead of staying with the building.
- →Your worry is the central air conditioner or the well pump restarting on battery. 7,200W continuous with a published 10,800W peak is 3,600W of starting headroom, and a reviewer ran exactly that combination of loads at onceA9.
- →Your system will spend most of its life sitting at full charge waiting for outages. At that duty cycle you want watt-hours, and 18,432Wh is 3,552Wh more than the EP900 offers.
Buy the EP900 + 3×B500 if you…
- →You are building a solar house rather than buying a backup. 9,000W of solar input is 3,400W more than the Ultra will accept, and no amount of money spent on the EcoFlow changes that ceiling.
- →You cycle every night, on time-of-use rates or genuinely off-grid. 6,000 cycles is 16.4 years of daily cycling against 9.6, which is one installation instead of two.
- →You want the system out of the living space, mounted and permanent, and you are entirely comfortable that every watt reaches you through the outlets already in your walls.
- →Your heaviest 240V load needs to run for hours rather than start and stop. The EP900's inverter is the larger one at 9,000W continuous.
If neither fits
If you pictured putting either of these in a truck, close the tab. They weigh 405.4 lbs and 466 lbs, and one of them has no outlets at all. Anyone who wants power away from the house wants a portable unit in the two to three kilowatt-hour class, the kind one person can lift into a trunk. And if what you actually want is energy independence with financing, a permitted roof array and a system somebody else warranties end to end, talk to a solar contractor about a purpose-built installation rather than comparing two appliances.
The Bottom Line
Buy the DELTA Pro Ultra stack. It is the bigger battery, the cheaper one by $5,799, and the one that works before the electrician arrives, which on a purchase this size is worth more than it sounds. The EP900 is a well-built permanent system, and the people praising its hardware are the ones who install things for a living, but it asks a large premium for less stored energy and pays you back only in cycles and solar input.
Which is exactly the condition that flips this. If your house will pull the pack down every night on a large array, the EP900's 6,000 cycles buy you one installation where the Ultra needs two, and that is a real answer rather than a hedge. Everyone else is buying storage that waits for storms, and for that job the EcoFlow gives you more of it for less money. Get the Ultra, and spend what you saved on the panels or the electrician.
Frequently Asked Questions
Answers drawn from the spec record and cited owner research.
Do I need an electrician for either of these?
For the EP900 it is not optional. It is hardwired, with no AC outlets and no USB of any kind, so it delivers power only through your existing house wiring after an installer ties it into the panel and selects the circuits it backs up. The DELTA Pro Ultra needs the same kind of work to protect whole circuits, but it carries three AC outlets, two 240V outlets and a 30A RV plug on the box, so it is useful immediately. Budget real time for either job: one reviewer's EcoFlow install ran nine hours and involved cutting out drywall to sink the panel.
Is the BLUETTI worth $5,799 more for 6,000 cycles?
Only if you are going to spend those cycles. Cycled daily, 6,000 against 3,500 is 16.4 years versus 9.6, which is the difference between one installation and two, and that matters more than the battery price because the second one comes with another electrician. If the system sits at full charge and discharges a few times a year, both packs comfortably outlive the 10-year warranty they share and the extra cycles are years you will never reach.
Which one is better for solar?
The EP900, clearly, on input: 9,000W against the Ultra's 5,600W. Whether that is worth anything depends on your roof, because an input ceiling only pays off across panels you actually own. From empty at full rated input, 18,432Wh divided by 5,600W is about 3.3 hours of perfect sun for the Ultra, against roughly 1.7 for the EP900's 14,880Wh at 9,000W. With a modest array, neither gets near those ceilings and the Ultra's extra 3,552Wh of storage is the more useful asset.
Can either of these start a central air conditioner?
The DELTA Pro Ultra publishes 7,200W continuous and a 10,800W peak, so it carries 3,600W of documented starting headroom, and a reviewer ran a central AC, a refrigerator and a well pump on one simultaneously. The EP900's inverter is larger at 9,000W continuous, but our record carries no published peak for it, so 9,000W is the figure to plan against. Compressors draw far more starting than running, which is why headroom rather than the continuous rating decides whether the unit restarts.
Can I use either for camping or in an RV?
Not as a trip unit. They weigh 405.4 lbs and 466 lbs, and the EP900 is wired into a building with no outlets on it whatsoever. The Ultra does carry a 30A RV outlet and two 240V outlets, which makes it genuinely useful to an RV parked at the house, but that is shore power from your garage rather than something you load for a weekend.
Brand matchup
EcoFlow vs BLUETTI: measured across every matchup →Related comparisons
Where to buy
EcoFlow DELTA Pro Ultra + 2 BatteriesPick
$7,999.00
$7,999.00 · direct from EcoFlow
Last checked 16 days ago. Prices move — check before you buy.
BLUETTI EP900 + 3×B500
$13,798.00
$13,798.00 · direct from BLUETTI
Last checked 16 days ago. Prices move — check before you buy.
Prices may vary by retailer and are subject to change.