Split Phase Inverter Guide (2026): Getting 120/240V for Well Pumps, AC and Dryers
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How we evaluated: WildJoule has not tested these inverters or power stations. Output figures come from manufacturer spec sheets and product pages (EG4, Sol-Ark, Victron, EcoFlow, Anker), checked between September and October 2026. Wiring guidance is general; a licensed electrician should design anything connected to a house panel.
A split phase inverter is what you need when the thing you most want running in an outage is a well pump, a central air conditioner or an electric dryer. Those run on 240V, and a standard North American house gets its 240V from two 120V “legs” that are out of phase with each other. A plain 120V inverter can’t produce that, no matter how many watts it’s rated for. That single fact rules out a lot of backup gear, and it’s the first thing to check before you buy anything.
The short answer
If any must-run load in your outage plan is 240V, you need true 120/240V split-phase output. Your options: an all-in-one split phase inverter (EG4 18kPV, Sol-Ark 15K, EG4 6000XP), two 120V inverter-chargers configured together (Victron MultiPlus-II), or a 120/240V power station (EcoFlow Delta Pro 3, Anker SOLIX F3800 Plus). If everything you need is 120V, a simpler 120V inverter is cheaper and fine.
Quick honesty note: I’m not an electrician and I haven’t wired a split-phase system into a house. I went deep on this because a well pump is the classic thing people discover won’t run on their new backup, usually during the outage. Having spent years where power cuts are routine, I’d rather you find that out from a spec sheet. Everything below comes from manufacturer specs and standard electrical practice, not my own install.
How split-phase power works in a house
Your utility transformer delivers two hot conductors (L1 and L2) and a neutral. Each hot measures 120V to neutral, and because the two are 180 degrees apart, they measure 240V to each other. Your panel alternates breakers between L1 and L2. A 120V circuit uses one leg and neutral. A double-pole 240V breaker uses both legs.
A split phase inverter recreates that arrangement from a battery. A single-phase 120V inverter gives you one leg only. You can sometimes jumper both panel buses onto that one leg to power all your 120V circuits, but 240V loads won’t run, and that shortcut puts both legs’ neutral current on one conductor, which is a job for an electrician to assess, not a weekend fix.
Which loads need a split phase inverter
| Load | Usually 240V? | Outage priority |
|---|---|---|
| Submersible well pump | Yes, most residential | High: no pump, no water |
| Central AC / heat pump | Yes | High in heat waves |
| Electric dryer, range, water heater | Yes | Low: big loads, usually skipped |
| Level 2 EV charger | Yes | Low in most outages |
| Fridge, freezer, lights, router, furnace blower | No, 120V | High |
Check the breaker, not the appliance’s reputation. A double-pole breaker in your panel means a 240V circuit. If your only 240V loads are a dryer and a range you’d happily skip during an outage, you may not need a split phase inverter at all. If you’re on a well, you almost certainly do.
Four ways to get 120/240V backup
1. An all-in-one split phase inverter
Most 48V hybrid and off-grid inverters sold in North America now output 120/240V natively. The EG4 18kPV delivers 12,000W at 240V; the Sol-Ark 15K-2P-N also delivers 12,000W, with a 200A pass-through; the EG4 6000XP gives 6,000W of split-phase output for off-grid systems. These are permanent installs with a 48V battery bank and, normally, an electrician. Our best hybrid inverter picks compare them, and the EG4 18kPV review goes through the most popular one in detail.
2. Two 120V inverter-chargers working together
Victron’s MultiPlus-II 120V units can be configured in multi-unit setups through the VE.Bus port, which is how Victron systems produce 120/240V. Each 48/5000 unit delivers 4,000VA at 25°C. The modular approach costs more and needs configuration, but each unit has a 19W zero-load draw, which matters on small off-grid systems.
3. A 120/240V portable power station
This is the no-install route for renters and anyone who wants backup in weeks rather than months. The EcoFlow Delta Pro 3 puts out 4,000W at 120/240V from 4,096Wh, and the Anker SOLIX F3800 Plus puts out 6,000W at 120/240V from 3,840Wh. Both can feed a generator transfer switch or inlet, which is the safe way to reach a 240V well pump circuit. Our generator transfer switch guide explains that hookup.
4. A 120/240V generator alongside a 120V battery system
Some households run 120V loads from batteries and start a generator with an L14-30 outlet only when the well pump or AC is needed. It’s cheaper up front, but you’re back to fuel, noise and carbon monoxide risk. Read our portable generator carbon monoxide guide before going that way.
Sizing a split phase inverter for a well pump or AC
Running watts are only half the story. Motors draw several times their running current for a fraction of a second at start-up, so the split phase inverter’s surge rating, and how long it can hold that surge, decides whether the pump starts. That’s why EG4 publishing 14,700W for 10 minutes on the 18kPV is more useful than a bare “peak” number. Find the locked-rotor amps (LRA) on your pump or compressor nameplate, multiply by 240V for a rough starting figure, and compare it with the inverter’s surge rating. Soft-start kits on air conditioners cut that inrush and can make a smaller system workable.
Leg balance matters too. With split-phase output, 120V loads land on one leg or the other. If your critical-loads panel stacks the fridge, freezer and microwave on the same leg, that leg works harder than the other. Many split phase inverter spec sheets list a per-leg or imbalance limit; check it, and ask your electrician to spread 120V loads across both legs. For the battery side of the math, use our home battery backup sizing guide.
Grounding and neutral bonding change with split-phase systems too, especially when a transfer switch is involved. Our ground vs bond explainer covers the basics, and the rules themselves live in the NFPA 70 National Electrical Code.
Frequently asked questions
Can I run a 240V well pump on a 120V inverter?
No. A 240V pump needs both legs of a split-phase supply. You need a split phase inverter, two units configured together, a 120/240V power station, or a 120/240V generator.
Is split-phase the same as two-phase or three-phase?
No. Residential split-phase is one transformer winding center-tapped to give two 120V legs and 240V between them. Three-phase is a separate commercial supply with three conductors 120 degrees apart.
Do power stations with 240V output need a transfer switch?
To power house circuits, yes: a transfer switch or an inlet with an interlock, installed by an electrician. Never backfeed a dryer outlet with a double-male cord.
How big a split phase inverter do I need for central AC?
Size it from the compressor’s running watts and its starting surge. Check the nameplate LRA against the inverter’s surge rating and how long it can hold that surge. A soft-start kit lowers the surge and can let a smaller system start the compressor.
Last updated: October 6, 2026. Split phase inverter specs are manufacturer-stated, not tested by WildJoule. We do not display live prices.
