You might not be allowed to install a 5kW Solar System in Sydney

The energy distributors in Sydney (both Ausgrid and Endeavour Energy) regulate what size solar system you can install on a house with single-phase power. This means that some households are not allowed to install a 5kW solar system or greater on their home unless they go through the costly process of upgrading to three-phase power.

There is a lot of misinformation around at the moment, and the regulations have recently been updated by Ausgrid making the situation even more confusing. So here is the latest information for both Ausgrid and Endeavour Energy, and advice on how you can maximise system output to get the most bang for your buck.

Solar Power with Single Phase Power

Ausgrid Distribution AreaA house with single-phase power in Endeavour Energy is limited to a 4.99kW array of panels with an inverter that is also less than 5kWs.

In Ausgrid the size of a solar system installed on a house with single-phase power is limited by the size of the inverter and not the panel array (sort of, see below).

As a solar power installer in Sydney, we are not permitted to install a single phase 5kW inverter, unless it has been de-rated (or wound back) to less than 5kW. Since these regulations were brought in, many manufacturers derated their 5kW inverters to slightly less than 5kW. This includes the 5kW SMA Sunny Boy and a number of the Chinese models.

Not sure if you are in Ausgrid or Endeavour Energy? Click here to find out – you just need to enter your postcode.

Your Options for a 5kW Solar System in Endeavour Energy

If you are looking for a 5kW system, in most cases we recommend buying a single-phase system smaller than 4.99kW, even if you have 3 phase power.

  1. If you have single phase power you are limited to an array of 4.99kW and the inverter must also be less than 5kW.
  2. If you have three phase power, a single phase inverter will work perfectly well with your meter board, because your new digital meter reconciles the 3 phases of your home, essentially performing the function of a 3 phase inverter. Because of this, we rarely recommend installing a 3 phase inverter for a system under 5kWs, it is a complete waste of money in most cases. Detailed information on this is available here.
  3. If you have three phase power and you are considering battery storage, you will most likely need to invest in an upgradeable and battery ready systems such as Enphase or SolarEdge. Please contact us for more information if you are thinking about adding battery storage in the future as a number of three-phase inverters are not battery ready or expandable.
  4. Even without bringing batteries into the equation, a 7kW SMA Tri Power inverter is only $400 more than a 5kW model. If you have high power consumption, by installing a 7kW system, you can save up to a further $800 a year off your power bills annually compared with a 5kW system, reducing the time the system takes to pay for itself.

Furthermore, the government rebate is based on the size of the panel array. For example, based on the current STC price of $39, a 7kW system comes with a $5,772 rebate whereas a 5kW system comes with a rebate of $3,822. This increase of $1,950, for the most part, covers an extra 2kW worth of panels. As the mantra goes: “you are paying for a team of solar installers to drive out to your house and install a solar system. Why not get them to throw a few more panels in the back of the van?”

  1. Look at installing an Enphase Micro Inverter System. An Enphase system is fully compatible with both three phase and single phase power and is easily upgradeable, making it the preferred choice for any 5kW system.

We are now installing over 50% of our systems with Microinverters. The 5th generation microinverters from Enphase are now available, and Solaray has grown to be the largest installer of Enphase systems in NSW. For more information about Enphase systems have a look at the 10 Key Benefits of Enphase Micro Inverters.

Your Options for a 5kW Solar System in Ausgrid

Ausgrid has recently changed its regulations for homes with single phase power. The maximum size of a system is now only determined by the inverter’s size, not the size of the panel array.

This is big news as it means households can install larger arrays on a single phase home to further reduce their power bills. Why? Because it is common practice to oversize an inverter by around 130%, meaning it is now possible to get up to around a 6.5kW system, even if you have single phase power.

Enphase Micro Inverter Systems

Enphase has two models – the S230 and the S270. For more information on which micro inverter is best, have a look at our article on how to choose a microinverter. As a quick summary, the S230 inverter is suitable for panels up to around 275W. This means that Solaray can now install an Enphase system with 21 x M230 microinverters as 21 X 230W = 4.83kW.

A 21-panel system can produce significantly more than 5kWs. For example, a system using one of our most popular panels from Trina Solar – the Trina Honey 275W panel will be a 5.8kW system.

We currently use the S270 micro inverter for high-efficiency panels such as the LG NeON 2 335W module. For more information about maximising your output through system design please call the Solaray Team on 1300 525 451. We are the largest installer of Enphase systems in NSW and have Enphase experts that can help you design a system that maximises output to help you get the most from your investment in solar power.

String Inverter Systems

Although we are now installing most of our systems with microinverters, for the right household a string inverter can still be a viable solution. This is especially true when designing a system to maximise output on a single phase connection.

An array of panels can be up to 130% to 140% larger than the size of an inverter without any significant loss in efficiency (less than 1%). This means you can essentially have a fully functional 7kW system using a 5kW inverter. Oversizing an inverter will not ‘over-work’ the inverter. It doesn’t get too hot, it doesn’t shorten the inverter’s lifespan; from a technical standpoint, it’s all good. In terms of performance, the inverter ‘clips’ the output, but only during the middle of the day and only on the best days of the year.

On the days where some clipping does occur, the loss is, for the most part, made up by the fact that you have better panels outputting more power in the morning and during the afternoon. 

In winter and on days when it’s not ideal for solar an oversized panel array will give you more power as shown below.

oversized enphase solar systemoversized enphase solar system winter

If you have any questions regarding these regulations and your options, please call us on 1300 525 451. We would be happy to help recommend the best option for your home or business.

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  1. Anonymous

    I have a solar installer trying to sell me a 6.6KW system. will i be allowed to install it? I actually want a 10KW system but he said that was too big. hope you can help. thanks Tanya

  2. Tanya ritchie

    I have a solar installer trying to sell me a 6.6KW system. will i be allowed to install it? I actually want a 10KW system but he said that was too big. hope you can help. thanks Tanya

    • Solaray

      Hi Tanya, it is possible to install a 10kW solar system but you will need to use a specific inverter that allows for export limitation. Please give us a call on 1300 221 586, we would be happy to talk through your options.

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