When you connect an inverter to your power supply, the number of phases matters — both for what the inverter can accept as input and what it can deliver as output. Single-phase and three-phase inverters are not interchangeable. Using the wrong type results in an inverter that cannot connect to your supply at all, or one that fails to deliver power to your equipment correctly. This article explains the electrical difference, shows you how to identify your supply type, and helps you determine which inverter you need.
What single-phase and three-phase mean
All AC electricity is generated by rotating a coil of wire inside a magnetic field. When you spin one coil, you get one alternating current — one phase. When you spin three coils offset by 120 degrees from each other, you get three alternating currents that are always 120 degrees apart in time — three phases.
Single-phase supplies deliver one sinusoidal voltage between a single live conductor and neutral. In most countries this is 230 V at 50 Hz (or 120 V at 60 Hz in North America). Almost all residential properties and small commercial premises are connected to single-phase supply.
Three-phase supplies deliver three sinusoidal voltages, each 120 degrees out of phase with the others. The voltage between any live conductor and neutral is 230 V; the voltage between any two live conductors is 400 V (230 × √3). Three-phase is used where higher power is required — large commercial and industrial sites, and some larger residential properties in some countries.
Single-phase: one sine wave. Three-phase: three sine waves, each 120° apart, providing smoother power delivery and higher total capacity.
How each type works — interactive comparison
Select each type to see how it works, what it is used for, and what to look for in an inverter specification:
How to identify your supply type — four methods
Before purchasing any inverter, confirm whether your site has single-phase or three-phase supply. Use any of these four methods:
Which loads require three-phase?
Not all equipment requires three-phase supply. The key distinction is between three-phase motors and other loads:
Loads that require three-phase
Three-phase motors are the primary reason three-phase supply exists. They are simpler, more efficient, and more powerful than single-phase motors of equivalent size. Large pumps, compressors, industrial fans, lifts, CNC machines, and most heavy manufacturing equipment use three-phase motors. These loads require a three-phase inverter or VFD and cannot be powered from single-phase.
Large heating loads above approximately 10 kW are often distributed across three phases to balance the supply loading. Electric furnaces, large commercial ovens, and industrial resistance heaters may be designed for three-phase input.
Loads that work on single-phase
Almost all household and light commercial equipment is single-phase: all standard plug-in appliances, lighting systems, computers and IT equipment, small air conditioning units (up to approximately 5 kW), domestic heat pumps, and EV chargers up to approximately 7.4 kW (32 A). Even in a building with three-phase supply, these loads connect to a single phase.
Full specification comparison
| Attribute | Single-phase inverter | Three-phase inverter |
|---|---|---|
| Output voltage | 230 V (or 120 V) L-N | 230 V L-N · 400 V L-L |
| Number of output conductors | 2 (L + N) | 4 (L1 + L2 + L3 + N) |
| Typical power range | 300 W – 30 kW | 5 kW – multi-MW |
| Three-phase motor loads | ✗ Not compatible | ✓ Native support |
| Grid phase balancing required | ✗ Loads one phase only | ✓ Balances all three phases |
| Residential use | ✓ Standard choice | ~ Where 3-phase supply exists |
| Industrial use | ~ Small loads only | ✓ Standard choice |
| Solar grid export compliance | ✓ On single-phase grid | ✓ On three-phase grid; often required above 5 kW |
| Relative cost (same kW rating) | Lower | Higher |
| Cable complexity | Simple (2 conductors) | Higher (4–5 conductors) |
| Ripple / power smoothness | Pulsates at 100 Hz | Smooth — 6× rectification frequency |
| Maximum grid export (typical) | Up to 5 kW (some markets 3.68 kW) | Required above 5 kW in most markets |
Decision tool — which do you need?
Answer two questions to get a direct recommendation: