The verdict, in one paragraph
Among systems you can buy outright, the EcoFlow DELTA Pro Ultra leads at 7,200W continuous per inverter, and it is the only product here with a documented path to 21.6kW across three. Two linked Anker SOLIX F3800s publish 12kW, which is the highest sustained figure available without a wired sub-panel. A single F3800 is 6,000W, the DELTA Pro 3 is 4,000W, the BLUETTI Apex 300 is 3,840W, and the 120V tier tops out around 3,000W. The highest residential figure published by anyone is Tesla's Powerwall 3 at 11.5 kW, but that is installed, hardwired equipment rather than something you buy and plug in. The number to understand before any of this: a 200A service is 48kW, so even 21.6kW is under half a house, and "whole home" always means load management.
Published continuous output, ranked
| System | Continuous output | Voltage | Multi-unit ceiling |
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| Tesla Powerwall 3 (installed) | 11.5 kW | 120V/240V | Up to 4 Powerwalls per system |
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| Anker SOLIX F3800, two units | 12 kW | 120V/240V native | Up to 2 units, 53.8 kWh |
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| EcoFlow DELTA Pro Ultra | 7,200 W per inverter | 120V/240V native | 21.6 kW across 3 inverters |
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| Anker SOLIX F3800 | 6,000 W | 120V/240V native, both at full rating | 12 kW paired |
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| Anker SOLIX F3800 Plus | 6,000 W max; 120V outlets capped at 2,400 W | L14-30 split-phase port at 6,000 W | Not published separately |
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| EcoFlow DELTA Pro 3 | 4,000 W | 120V, or 240V as a selected mode | Not published as a continuous figure |
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| BLUETTI Apex 300 | 3,840 W | 120V and 240V simultaneously | 11.52 kW scaled |
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| Anker SOLIX F3000 | 3,600 W | 120V only | 7,200 W with two units and a hub |
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| Jackery HomePower 3000 | 3,600 W | 120V only | Not published |
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| EcoFlow DELTA 3 Ultra Plus | 3,600 W | 120V only | Not published |
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| EcoFlow DELTA 3 Max Plus | 3,000 W | 120V only | Not published |
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| BLUETTI Elite 400 | 2,600 W | 120V only | Not published |
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Every figure is the manufacturer's own published continuous rating, from the pages cited under Sources. Tesla's Powerwall 3 is listed first because it publishes the highest residential figure, but it is installed equipment that is not sold through a retail buy button, so it is not a pick. Current prices sit inside the buy buttons above, each with the date it was last refreshed.
Continuous is not surge, and the gap is the whole decision
These two specifications answer different questions and the wrong one gets quoted constantly:
- Surge is extra wattage for about a second, at full voltage. It decides whether a motor starts. A compressor draws three to five times its running current for an instant and then settles.
- Continuous is what the inverter sustains indefinitely. It decides what you can run at the same time, for hours.
A unit can be excellent at one and ordinary at the other. The DELTA Pro 3 publishes 8,000W of surge against 4,000W continuous — a 2x ratio that starts almost anything but sustains a modest load. The F3800 publishes 9,000W surge against 6,000W continuous — a 1.5x ratio that starts less aggressively but runs far more.
If your problem is "the air conditioner will not start," you want the surge ranking, and a soft starter is often the cheaper fix. If your problem is "everything trips when the dryer is on," you are on the right page.
Two more figures that are not continuous output
- X-Boost. EcoFlow's published description is intelligent voltage control that marginally reduces voltage so a higher-rated appliance runs on a lower-rated inverter, and EcoFlow states it is for resistive appliances — kettles, hair dryers, ovens — and that it is unavailable while the unit is charging. X-Boost to 6,000W does not mean 6,000W continuous.
- Power lifting. BLUETTI's equivalent term, and it sits where a surge rating would. The Apex 300 publishes 7,680W lifting against 3,840W continuous.
When a listing shows three wattages, the smallest one is almost always the real sustained figure, and it is the one this page ranks.
The arithmetic that caps "whole house"
This is the part that reframes the question. A standard residential service is 200 amps at 240 volts, which is 48,000 watts of theoretical capacity. A 100A service is 24,000W.
Against that, the best system on this page sustains 7,200W from one inverter and 21.6kW from three. The highest published residential battery figure anywhere — Tesla's 11.5 kW — is under a quarter of a 200A service.
Houses rarely draw their full service, so this is not as bad as it sounds. But it means the honest version of whole-house backup is a managed subset of circuits, not the whole panel. Both major smart panels publish 12 circuits, which is exactly the design admitting it. Typical large loads, using the published figures this site works from:
| Load | Running watts | What it does to a 6,000W budget |
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| Electric water heater | 3,000-4,500 W | Takes half to three quarters of it |
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| Central air, 3 ton | 3,000-3,500 W | Takes over half, before the start |
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| Central air, 2 ton | 2,000-2,500 W | A third |
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| Heat pump auxiliary strip heat | 9,600-19,200 W at 240V | Exceeds it outright — shed this, always |
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| Space heater | 750-1,500 W | Up to a quarter, for one room |
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| Furnace blower | 300-800 W | Negligible, and the best value on the list |
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| Refrigerator | About 150 W average | Negligible |
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Water heater, central air, space heater and furnace blower figures are Champion's published wattage chart. Strip-heat figures are Goodman's published kit capacities at 240V. The refrigerator figure is this site's standing working average.
Stacking batteries does not raise continuous output
This is the single most expensive misunderstanding in the category. Adding expansion batteries multiplies kilowatt-hours; the inverter wattage does not move. Five extra batteries on a DELTA Pro Ultra takes it to a published 30kWh of storage and leaves it at 7,200W of output.
Output only rises when you add inverters, which is why every high figure in the table above is a multi-unit configuration: 21.6kW is three EcoFlow inverters, 12kW is two Anker units. How much home battery capacity you can stack covers the capacity side, and it is a genuinely separate purchase decision from this one.
How to work out the number you actually need
- List what must run simultaneously, not everything you own. The sum of running watts for that list is your continuous requirement.
- Add the largest single starting surge on that list to the running total, and check it against the unit's surge figure rather than its continuous one.
- Decide what you will shed. Water heater, range, dryer and strip heat are the four that break every budget, and switching them off costs nothing.
- Check the voltage. A 240V load needs a split-phase source, and continuous output is irrelevant if the voltage is wrong.
- Then check runtime separately. High output drains a battery fast — sizing a home battery does that arithmetic.
Where a generator still wins
Being straight about it: if the requirement is genuinely high sustained output for days, an engine is still the answer. A 9,500W dual-fuel portable sustains more than any single battery on this page and refuels in minutes, and a standby unit goes well beyond that.
What a battery buys instead is silence, no maintenance schedule, instant transfer and indoor operation. The strongest arrangement for a house with large loads is usually both — running a battery and a generator together covers which systems accept generator charging and at what wattage, and generator versus home battery runs the economics.
Who should buy on continuous output
- Several large loads at once, installed system: DELTA Pro Ultra with the Smart Home Panel 2, scaling to three inverters if the house justifies it.
- Maximum sustained output without a sub-panel: two Anker SOLIX F3800s at a published 12kW.
- One serious 240V load plus a critical-load panel: a single F3800 at 6,000W. This is the sensible answer for most houses asking this question.
- A critical-load list with one 240V circuit: DELTA Pro 3 at 4,000W.
- Best sustained output on a budget: BLUETTI Apex 300 at 3,840W with simultaneous split-phase.
- Nothing on 240V: stop at 3,000W and spend the difference on kilowatt-hours instead.
The short version
Continuous output is the specification that decides what runs together, and it tops out far lower than people expect: 7,200W from the best single unit you can buy, 12kW from two linked Ankers, 21.6kW from three EcoFlow inverters, against a 200A service worth 48kW. Ignore X-Boost and power lifting, because neither is a sustained rating. Remember that extra batteries add hours and not watts. And decide what you are willing to shed before you shop, because the water heater, the range, the dryer and heat-pump strip heat will break any budget on this page.
