Split Phase Inverters Explained: Getting 120/240V From One Unit

The Short Answer: A split phase inverter produces both 120V and 240V AC power from one unit, the same split-phase power a home or small commercial building gets from the grid. It does this by splitting its output into two 120V legs that combine to 240V, so a single inverter can run everyday 120V household appliances and 240V loads like a water heater, an air conditioner, or a well pump. For off-grid, solar, and backup systems that need 240V, a split phase inverter charger is what delivers it. 

Most homes and many small commercial buildings in the United States run on split-phase power, which supplies 120V for standard outlets and 240V for larger equipment from the same service. An off-grid, solar, or backup system has to match that, and a standard single phase inverter that only puts out 120V cannot run a 240V load. 

A split phase inverter solves this by producing both voltages from one unit, so the system powers the whole building the way grid power would. Understanding how split phase works, and what to look for in a split phase inverter, makes it easier to spec a system that runs everything on site.

What Is a Split Phase Inverter

A split phase inverter is an inverter that converts DC power from a battery into split-phase AC power, delivering 120V and 240V at the same time. It is the inverter type that matches standard US residential and light commercial service, which is why it is the right choice for a system meant to back up or replace that supply.

Single Phase vs Split Phase

A basic single phase inverter produces a single AC output, which is fine for small loads but cannot run equipment on other voltages. Split phase is a form of single-phase power that carries two 120V legs 180 degrees apart, so the two legs combine to 240V while each leg still provides 120V. A split phase inverter reproduces that, giving the same 120/240V split-phase system an electrician expects from grid power.

The practical difference shows up with larger equipment. A well pump, a central air conditioner compressor, an electric water heater, and an EV charger are wired for 240V, and they pull that voltage across both legs at once. A single 120V inverter has no second leg to pull from, so those loads will not run on it. This is the main reason a whole-building system uses split phase rather than a basic single phase unit.

How One Unit Makes 120 and 240 Volts

Inside a split phase inverter, the unit creates two 120V legs referenced to a shared neutral. Each leg to neutral is 120V for standard circuits, and leg to leg is 240V for larger equipment. That is how a single unit covers both the 120V AC output for outlets and the 240V output for heavy loads, with a clean pure sine wave output that sensitive electronics need.

What a Split Phase Inverter Can Power

Because it supplies both voltages, a split phase inverter can run an entire panel rather than a few circuits.

• 120V loads: lights, outlets, electronics, and most household appliances.
• 240V loads: a water heater, an air conditioner, a well pump, a dryer, or shop equipment.

That range is why split phase power is the standard for whole-building off-grid, solar, and backup power, in homes and in many commercial applications where the site needs 240V.

Split Phase Inverter Chargers and Hybrids

For most off-grid, solar, and backup builds, the split-phase unit is an inverter charger, which adds battery charging and automatic transfer to the inverter.