Single Phase VS Three Phase Power

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In Australia, the majority of residential homes and small business connected to the grid run off a single phase power supply. Businesses running commercial appliances or large residential properties requiring supply for heavy loads are connected to 3 phase power. 

The single phase power supply method is sufficient for a small to medium home or business using appliances not exceeding 1,000 watts. These are general electrical applications like a washing machine or dryer. Appliances exceeding this demand will require a 3 phase connection, for example ducted air-conditioning, pool heaters and machinery.

New property developments offer an opportunity to future proof your home or businesses sustainability right from the get go. If you are building from scratch or completing a large renovation and in the crucial stages of planning and designing I would suggest you run your eyes over our blog : Integrating solar power into your new build or home renovation. There is some key information there, highly beneficial to the planning stage!

Naturally you want to make an informed decision when completing upgrades to your home or business. Combining a solar power system with the right power supply will provide you with the best desired performance outcome. 

Now you’re probably scratching your head… What does this all mean? You had no idea there were differences in power supply… Am I right?

Well here we aim to explain the differences between these connections and the benefits that are attributed to each situation.


Single Phase Power 

  1. The most common connection in residential homes and small businesses.
  2. Tends to be more affordable and versatile when running standard home appliances. 
  3. Power is transported using two wires; active and neutral.
  4. Electricity is drawn from the grid through the active wire.
  5. The neutral wire is connected to the earth at your switchboard and provides a path back to the switchboard in the event of an overload or fault. 
  6. If a fault occurs the breaker will trip cutting off your electricity supply, keeping you safe.

In terms of solar power generation; a single phase home can install a 5kW inverter and not be restricted by export limitations set by Energex the local distributor in South East Queensland. You may install up to 6.66kW worth of solar panels on a 5kW inverter to maximise the potential output and savings. 

Energex regulations allow for home and business owners to install up to a 10kW inverter on a single phase connection. There are few 10kW single phase inverters currently in production. It is common practice to have 2 x 5kW inverters installed. However, you will be export limited to 5kW. Put simply anything you generate and not used within the property can-not be exported back to the grid for a solar feed in rate.

There are situations where this is beneficial for the property owner. Before deciding on a solar system of this size we always recommend doing your research and discussing your individual situation with a trusted company. 


Determining a single phase connection at my property.

4shore solar single phase switchboard     

Three Phase Power 

  1. Offers maximum load and enhanced performance.
  2. Common in larger homes, commercials sites and medium – large businesses.
  3. Has four wires; 3 active and 1 neutral.
  4. The neutral wire is connected to the earth at the switchboard and will circuit back to the switchboard in the event of a fault, protecting your premise. 
  5. Recommended when using multiple appliances or large machinery. 
  6. Allows you to power the battery on an electric vehicle three times faster than single phase power. 

Three phase power offers superior benefits to most properties. In the scheme of modern day necessities we advise;  future-proof your home for inevitable expansion. Thinking about adding any of the following mod-cons to your premise? 

  • Installing a pool heater.
  • Adding ducted air-conditioning. 
  • Purchasing an electric vehicle.
  • Adding batteries to your solar system in the future.

When it comes to solar it can be highly beneficial for you to upgrade from single to three phase power. Not all situations are the same so as we always harp on, do your research and listen to someone who has a wealth of experience. 

The maximum rated inverter capacity for 3 phase homes is 15kW. Here you are able to fully export any unused power back to the grid for the determined feed in rate with no limitations incurred from the grid.

Energex legislates on residential properties you can install up to a 30kW inverter however, this is export limited to 15kW. Your power bills would have to exceed $3,000 a quarter for this to be a viable option, not to mention the vast amount of roof space required.   

Businesses under-go a slightly different process when seeking distributor approval above 15kW. A large amount of business applications for connection undergo technical assessment, most pass. We can-not guarantee the outcome of the assessment. There may be limitations which all accredited installers are required to adhere to. Export limitations confine excess power being directed back to the grid for a determined rate of sale due to network constraints. 

If in the unlikely event your solar system does not pass the distributor assessment. It means your proposed solar power system will not work effectively on the electricity network. 

Typically, reasons for no approval may include :

  • There are a number of solar PV systems on the same network transformer as your premise.
  • The network transformer capacity is too small or other network components are unlikely to support the proposed system.
  • The proposed system is a long distance from your network transformer. 
  • Your service line or electricity cables within your property boundary may be too long or not have enough capacity. 

A technical advisor will notify your solar company of any changes required to your application. A connection offer is raised once an application passes assessment. The solar company enters into the terms of the agreement on behalf of the client and a contract is then established. This process can take up to and beyond 60 business days for applications rated over 15kW dependent on the components of the request and site specific details. 


Determining a three phase connection at my property 

4shore solar 3 phase switchboard

Should I install a 3 phase inverter on my 3 phase connection?

In short, yes! Any ethical company will install a 3 phase inverter on a 3 phase connection. Most homes on 3 phase power have appliances running across the three circuits. Let’s look at a real world scenario so you get an idea of our intended message. 

Real World Scenario

I have a 3 phase connection and I have a heat pump for my pool running on Phase B, the ducted air-conditioning is on Phase C and general usage is running off Phase A. Should a single phase inverter be installed the solar systems production would only reduce the consumption on Phase A; exporting excess back to the grid. Therefore Phase B + C you are still drawing power directly from the grid at the determined rate usually between 0.20c – 0.30c.

When installing a 3 phase inverter on a 3 phase connection you guarantee consumption is reduced across all three phases; when the solar panel system is producing power. Therefore, your heat pump, ducted air-conditioning and general consumption are all being minimised. Consequently relying less on the grid and utilising the suns arrays increasing your return on your investment.  


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When discussing export limitations in the governing territories of Ergon and Essential Energy in NSW. Each individual situation undergoes technical evaluation. There are no definitive rulings which we can follow in order to provide you assurance on how the grid will deem your system. Many factors are assessed and NO-ONE can be sure of the outcome in these governing areas.