If you are looking at solar or a solar battery for your home, one of the questions you are guaranteed to be asked is, is your home single or three phase?

We are going to cover off what it actually means, how to work out what you have and the impacts it has on solar and battery.

What actually is single phase and three phase power?

When we talk about phases it is referring to the distribution of load.

Single phase involves one wire feeding your house with power while three phase feeds it with three.

As you can see from the basic diagram, in a general single phase scenario there is one active wire fed into the home with and one neutral. Three phase supply has three active wires feeding the home and one neutral.

The reason behind this as we mentioned earlier is all about the distribution of load.

Historically, most homes were built with a single phase connection.

If we think back not that long ago, we ran our lights, a fridge, a TV and that was pretty much it. These days, nearly everything we touch is plugged into the wall. Most homes you can just speak and something will turn on and that’s before we even consider the uptake in electric vehicles.

So, in comes three phase power. Many new buildings are now being built with three phase power and recently we have seen a lot of homes spending the money to upgrade to support their growing demand.  

Three phase simply supports more demand from your home because it can balance your load across three phases or wires and not just one. It is that simple.

If you speak to an electrical engineer you will end up with a much more complex explanation and some of the analogies we have come across are more complex than the problem and that is why we decided not to waffle on about 120 degree intervals and sine wave voltages.

How does single and three phase impact installing solar or batteries?

It is really about picking the right system for your home and if you have a single or three phase connection, is just another of many considerations.

A couple things thing each connection can impact are:

Depending on who your distributor is, there will be a cap on how much power you can export per phase. This gets talked about a lot but when you break it down in a residential setting, it is never the end of the world. Where we are, our distributor is Ausgrid and they allow up to 10kWs per phase which is pretty damn good when you compare it to the majority of other distributors who only allow 5kW’s per phase. To learn more about exporting, check out our video on export limiting.

You have to pick the right inverter. Any good solar retailer will only quote an appropriate option but keeping it simple, a single phase home can only have a single phase inverter. A three phase home can have either a three phase or single phase inverter.

So how do you know if you have single phase or three phase power?

The simple way is to head out to your meter box, open it up and have a look. If you have three main switches or three fuse cartridges, you have three phase power. If you only have one, you have a single phase connection.

If you still aren’t sure, just take a photo of your metre box with the lid open please and send it our way. We will let you know no problemo.

And that is it! If you are more of a video person, check out the video we made below that covers everything off.

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David Green

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