What’s The Maximum Size Solar System I Can Install?


If you’ve been considering installing solar or expanding your current system you may have an ideal size in mind that will fulfil your energy needs and hopefully make your reliance on the grid minimal. However, you may not know that each state’s local electricity networks have restrictions on the size system your property can install (if you are grid connected).

Before purchasing a solar system it’s important to speak to your local electricity network and solar installer to ensure the size you have selected is approved or if you are wanting to install a system larger than the pre-approved size that you are following the correct steps to do so.

Why Are There Limits?

So why put limits on renewable energy? Whilst the dream may be to go completely off-grid the reality is that most solar systems are grid-connected. This is so when the sun is not out, and your solar system is not generating any energy your property can still function and run appliances, lights etc. The issue is that when the electricity distribution network was designed it was set up to send electricity in one direction. From the grid to your property. When grid-connected solar came along this one direction electricity became two way with solar homes sending their excess energy to the grid in exchange for a Feed-in Tarif.

The concern network owners have is that too much energy being fed into the grid might cause operational problems and risk disruption to the electricity flow which is why they have set restrictions on the amount of electricity a property can generate.

What Determines The Size System I Can Install?

Location and whether your home is single phase or 3 phase connected are the two main factors which will determine what size system you are restricted to.

Single Phase

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

3 Phase

Common in large homes and businesses.

When receiving solar system quotes the installer will be able to assist you to determine if you are Single Phase or 3 Phase connected.

Size Limits And Restrictions

A 5kW system seems to be the sweet spot that network owners are happy with residential properties to install, with most states and territories giving automatic approval to rooftop solar systems 5kW or under for a single-phase property. 3 phase properties can be approved for up to a 30kW system.

Whilst it’s possible to gain approval for a size larger than these limits it may have implications on whether you can receive the Feed-in Tarif (FIT) for any excess energy your system generates.

The following list is a guideline of the limits for pre-approved for solar system sizes per state.

Australian Capital Territory

Energy Retailer: ActewAGL

  • Single phase: 5 kW

New South Wales

Energy Retailer: Ausgrid

  • Single phase: 5 kW

Energy Retailer: Essential

  • Single phase: 3 kW (rural)
    Single phase: 5 kW (urban)

Energy Retailer: Endeavour

  • Single phase: 5 kW
  • 3 phase: 30 kW

Northern Territory

Energy Retailer: PowerWater


  • Single phase: 5 kW
  • 3 phase: 7 kW (10 kW per phase inverter limit)

Private/residential & small commercial:

  • 3 phase: 30 kW with zero export limiter inverter (10 kW per phase inverter limit)


Energy Retailer: Energex

  • Single phase: 5 kW
  • 3 phase: 15 kW

South Australia

Energy Retailer: SA Power Networks

  • Single phase: 5 kW
  • 3-phase: 30 kW


Energy Retailer: Tas Networks

  • Single phase: 5 kW
  • 3 phase: 30 kW


Energy Retailer: United Energy

  • Single phase: 10 kW
  • 3 phase: 30 kW

Energy Retailer: CitiPower

  • Single phase: 5 kW
  • 3 phase: 30 kW

Energy Retailer: Jemena

  • Single phase: 10 kW
  • 3-phase: 30 kW

Energy Retailer: AusNet

  • Single phase: 5 kW
  • 3-phase: 15 kW

Western Australia

Energy Retailer: Western Power

  • Single phase: 10 kW
    3 phase: 30 kW

Energy Retailer: Horizon Power

  • Eligibility to install rooftop solar depends on which town you live in and you will need to contact the Energy Retailer to discuss.

Unsure what system size your network allows? Speak to local installers about your options for solar system sizes!

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Understanding Batteries

Off-Grid Systems

For some households a battery system can be of great benefit and minimise a home’s reliance on the grid. However, it’s important to understand for a battery to be useful your solar system needs to be generating excess energy for the battery to store, which you can then use at night or when the sun is not out.

When selecting a battery, you’ll want to invest in a system that is most suited to your home and can drive the best return on investment (ROI). Despite a larger upfront cost, a higher quality battery may significantly increase your ROI.

    Battery systems start from $6,000 and costs can vary greatly based on the following factors:

  1. Cycle Life-Time

    The number of times a battery can fully charge and discharge.

  2. Battery Power (kW)

    How fast it can be charged or discharged.

  3. Storage Capacity (kWh)

    The maximum amount of energy a battery system can store.

  4. Battery Management System (BMS)

    An electronic ‘smart’ system that gathers data and manages the battery ensuring it does not overload or operate outside of its safe functioning zone..

  5. Inverter

    Battery systems require their own inverter if your solar system does not have a hybrid inverter.

  6. 'All-In-One Unit’

    A system which includes the battery, BMS and an inverter all in one unit.

  7. Warranty

    Length of time or cycles the battery system is under guarantee.

  8. Blackout Protection/Backup

    It’s important to note this is not a common feature of a battery system and could cost thousands of dollars to include. Blackout protection not only requires additional components but also a specialised installation and rewiring. For grid-connected homes, the cost for blackout protection can outweigh the benefit.

Additionally, if your purpose for adding battery is to go Off-Grid and become completely independent from the grid you will need to ensure your solar system can generate enough energy to power your home and your battery system is large enough to store this energy. For homes in metro areas going Off-grid is not cost effective and is only recommended for those in remote areas with limited access to the grid. Off-grid solar systems with battery start at approximately $30,000.

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