What does split-phase 120/240V mean on an inverter?

The inverter synthesizes two 120V legs 180 degrees apart, so each leg measures 120V to neutral and the two legs together measure 240V. That is the exact arrangement a North American panel expects for both small 120V loads and large 240V appliances.

Can I use a 230V inverter in a US home?

No. A 230V output applied to a 120V North American circuit overvolts lights, TVs and chargers and damages them. You need a unit explicitly rated 120/240V split-phase, not a standard single-voltage inverter.

How big a split-phase inverter do I need for home backup?

3.6kW covers light 120V essentials; a 7.2kW unit handles a typical 500kWh-per-month home including some 240V loads; 10 to 12kW covers whole-home with electric heat or larger HVAC. Size to the largest 240V appliance you actually run.

Which regions use split-phase besides the US?

Canada, Mexico, much of Central America and Caribbean grids built on the North American standard. Many off-grid and unstable-grid markets there run 120/240V rather than 230V, so specifying the wrong inverter is a common, expensive import mistake.

Split-Phase Inverters for North America: 120/240V, Sizing, and Who Needs One

Most of the world runs single-phase 230V. North American homes do not. They run split-phase: two 120V legs that combine to 240V. If you sell or install a storage system there, a standard 230V inverter will not give your outlets the 120V they expect. This guide explains what split-phase is, why the output spec matters, how to size one, and where the demand actually sits.

What split-phase actually means

A split-phase panel has three wires: two hot legs, each 120V to neutral, and a neutral. Large appliances — dryer, oven, water heater, HVAC — connect across the two hot legs for 240V. Everything else — lights, receptacles, TV, fridge — runs on 120V from one leg to neutral. A storage inverter feeding that panel has to output both: 120V for the small loads and 240V for the big ones, derived from the same battery.

Why a plain 230V inverter does not fit

A European- or Australian-style 230V inverter outputs one AC voltage. Plug it into a North American panel and your 120V outlets see roughly 230V — instant damage to TVs and chargers. You need an inverter built for split-phase: it synthesizes two 120V legs 180 degrees apart, so the between-leg voltage is 240V and each leg-to-neutral is 120V. The spec sheet will say 120/240V split-phase or 100 to 120/240V. If it only says 230V, it is the wrong unit for that market.

Typical sizes and what they run

Common residential split-phase inverter sizes are 3.6kW, 6kW, 7.2kW, 10kW and 12kW. A 7.2kW unit we build, for example, pairs with a 16kWh battery and about eight solar panels, and covers a household using roughly 500kWh per month — fridge, lighting, well pump and the 240V loads, without frying the 120V ones. Below that, a 3.6kW unit suits lighter backup; above, 10 to 12kW covers whole-home including electric heat or a larger HVAC.

Sizing the battery and panels

Inverter size sets what you can run at once; battery size sets how long. For a North American home doing two days of backup on 120V essentials — fridge, lights, internet, a well pump — 10 to 16kWh is the usual bracket. Solar input depends on panel count and wattage: eight 400 to 620W panels is a common pairing for a 7.2kW inverter, enough to refill a 16kWh pack on a good sun day. Match the MPPT voltage window to your panel string, not just the watt total.

Where the demand is

The obvious market is the United States and Canada. But split-phase 120/240V also turns up across parts of Latin America — Mexico, much of Central America — and in Caribbean grids built on the North American standard. That matters because the same regions dealing with unstable grids and high electricity prices, the ones buying off-grid storage, often run this voltage standard rather than 230V. Specifying the wrong inverter there is a common, expensive mistake for first-time importers.

A quick check before you buy

Read the output line, not the brand. If it says 120/240V split-phase and the battery and PV input match your plan, it fits North America and its voltage twins. If it says only 230V, it does not. And size the inverter to the largest 240V appliance you actually run, not to your daily kWh.