Single Phase vs Three Phase Power | Infinite Energy

Single Phase vs Three Phase Power

Single Phase vs Three Phase Power

Written by Infinite Energy

single vs three phase

Homes and business connected to the grid in Australia will predominately use either single phase or three phase power.

This blog will explore the difference between single and three phase power, and how your phase will affect your solar PV system.


Single Phase

Used in most new homes and small businesses, single-phase electricity is transported via two wires: active and neutral.

Electricity from the grid (or your solar PV system) will only flow through the one active wire, while the neutral wire is connected to the earth at the switchboard.

The purpose of your home or business’s neutral wire is to provide a path back to your switchboard, the source of the electrical current, in the event of a fault.

This will trip the breaker or blow the fuse, cutting your electricity, and preventing you from getting electrocuted.


Three Phase

In contrast, three-phase power has four wires, three of which are active, in addition to one neutral wire, which is once again earthed at the switchboard.

Three phase electricity is common in both larger homes and businesses, and allows for smaller, less expensive wiring, and lower voltages.


How do I Find Out if I’m Single or Three Phase?

The easiest way to find out if your house or business is single phase or three phase is to check your meter box.

Single Phase

Single phase meter boxes only contain one fuse cartridge. (Black rectangle on the bottom right)

Three Phase

Three phase meter boxes on the other hand consist of three fuse cartridges. (Three black rectangles on the bottom left)

If you need assistance, simply email a photo of your meter box to

While both single and three phase homes and businesses are able to install solar, your phase will dictate the type and size of inverter you are allowed to install.


About Inverters

The solar inverter lies at the heart of a PV system. This sophisticated piece of electrical equipment is responsible for:

  • The conversion of DC electricity (produced by the solar panels) to AC electricity which can be used within your home or exported to the grid.
  • Controlling the voltage of the system to extract the maximum power available (referred to as maximum power point tracking).
  • Reporting on the solar system’s performance (either on screen, via bluetooth or the internet).


Inverter Size Limits for Single Phase and Three Phase Properties

Single Phase Properties

In most states, if your property is single phase, you can install an inverter up to 5kW in size.

Any larger and you may not be able to receive a feed-in tariff for any electricity your solar PV generates and is exported to the grid.

While it’s technically possible to install a larger sized inverter, stricter size constraints are often placed on properties with single phase connections than those with three phase connections.

This means that to install an inverter over 5kW in size, you’ll need to seek approval from your state’s network operator.

As your home is single phase power, you will need to install a single phase inverter.


Three Phase Properties

If you own a three phase property, you’re technically able to install both single and three phase inverters. However, because network operators will not allow an imbalance across the phases, you’ll either have to install three single phase inverters for each phase, or one three phase inverter that will work across all three phases.

While there is no limit to the size of the inverter you’re allowed to install, in many states your network provider will approve installations over 5kW on a case by case basis.

It’s also worth noting that installing an inverter over 5kW in size will void your ability to receive a feed-in tariff for any exported solar electricity in many states.


Regardless of whether your home or business is single or three phase, Australia is one of the best countries in the world to install solar power.

Infinite Energy stock single and three phase inverters from SMA, Fronius, SolarEdge and ABB. We have chosen these brands as they are reputable manufacturers, dedicated to producing inverters of the highest quality and efficiency.

We can help you decide the best inverter size and brand for your home or business, ensuring you receive the best possible return on your investment. For a no obligation quote, click here.


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