Western Australia Solar Feed-in Tariff: Can I increase my system size?

Western Australia suspended its 20c/kWh solar feed-in tariff (FiT) scheme at 8am 1 August 2011 with no state-sponsored scheme to replace it (although there is still a Solar Buyback scheme in place from WA electricity retailers).

Some people who already have a solar power system installed on their property and are receiving the FiT in Australia’s largest state may be asking themselves: “If I want to increase the size of my system, will I still be eligible to continue receiving my current rate?”

Can I expand my solar power system and still get the WA Feed-in Tariff?

The answer, according to the WA Office of Energy, is ‘yes’–but with a caveat.

Under WA FiT eligibility rules, solar power system size is defined by the capacity of the system’s inverter. You can increase the size of the solar panel array, but you cannot add a new inverter or replace your existing one with a larger one.

Keep in mind that there’s a limit to how much benefit you’ll actually see from putting on additional panels. If your inverter’s capacity is greater than the nominal capacity of your solar panel array(s), then it almost certainly makes sense to add on more panels. In some cases, it may even make sense to have a greater total solar panel capacity than your nominal inverter’s capacity – this is widely used and accepted technique in the solar industry these days. The Clean Energy Council’s design rules acknowledge this approach, but say that ‘overclocking’ of solar panel capacity should not be greater than 30%. For example, if you have a 2kW inverter, your solar panel array’s nominal capacity should not be more than 2.6kW.

If you didn’t have plans to increase the size of your system before the FiT scheme was cancelled, it is unlikely that you would opt to do so now. Unless, of course, your energy needs have begun to soar higher than you ever expected them to, in which case upgrading your system might be worth it even if it means losing the tariff.

© 2011 Solar Choice Pty Ltd


Western Australia Office of Energy, Residential Solar Feed-in Tariff FAQ


  1. We have a 1.5Kw sysem installed in 2012. We bought the house recently, our inverter is 2.5Kw. we are thinking adding few more panels so that we can optimise the system. we are getting FIT of 7.13 cents per Kwh.

    please advise me, if I add 6 panels of 250 W. will I be eligible for subsidy (STC). If we buy a new system, we get 20.5 STCs for every Kw system installed.
    Ideally, I should be getting 30.75 STC if I extend my system capacity to 3KW from 1.5 Kw.
    Please clarify.

    1. Hi Gani,

      Yes, you will be eligible for the STC subsidy, provided that you a) have an accredited solar installer put in the new panels, b) that the panels themselves are Clean Energy Council approved, and c) that you refresh the grid connection application (you need to let your network company know that you’re adding the panels on).

      Ordinarily if you live in another state I would warn that you may not want to add on the extra panels out of risk of forfeiting a solar feed-in tariff, but it seems that you’re not receiving the higher rate anyhow (it used to be 20-40c/kWh) – and in any case in WA they let you expand your solar panel array size as long as you don’t increase the inverter capacity (as per the above article).

      Good news for you, in any case! G0ood luck with your system.

  2. Which solar system is best a 4500watt system with twin inverters of 2. 6KW or one with 4.6KW. Does it make a difference which Phase they are on. Do the new digital meters change the consumer rates (residential) Will I get anything back for excess power going to grid?
    In Western Australia. very confusing re tarrifss and Buy backs>>>.
    Can you explain….. Urgent


    1. Hi Dennis,

      There is no solar feed-in tariff currently available that is supported by the government. Only the Renewable Energy Buyback schemes through retailers.

      The phase should not make a difference with regard to retroactively increasing your system size and still receiving the 44c/kWh WA solar feed-in tariff–you can’t increase the size of your system retroactively. As you can see on our feed-in tariff overview page, in WA if you are a Synergy customer, you are eligible for 7c/kWh, and if you are a Horizon customer, the rate is 1:1, meaning that you get the paid the same rate per kWh as you would be charged as an electricity customer.

      Hope this is helpful.

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