How we save $240PA by switching from Aurora tariff 31/41 to tariff 93

This post is part of my Sustainable House Day submission.

Have you heard of the Aurora (Tasmania) electricity tariff 93? It was originally known as the Time-Of-Use (TOU) tariff but appears to have been recently rebranded as the Peak-and-Off-peak tariff.

Most households use a combination of tariff 31 for light & power, and tariff 41 for heating & hot water.

Sustainable Living Tasmania did a huge data collection/ modeling exercise with 100 real households and a further 1000 spreadsheet variations, and determined that 95% of households would be better off switching from tariff 31/41 to tariff 93. The more energy you use, and the more energy you can time-shift to off-peaks periods, the more money you can save.

Note that tariff 93 requires a meter that can periodically transmit your power usage back to Aurora via radio. You need to factor in an electrician changing your meter if necessary. This will affect the payback calculations. As far as I can tell, there’s no other fee for switching between tariffs.

you’ll need this meter – EDMI Atlas Mk7A

In summary from a 2019 Aurora PDF and current pricing:

Aurora domestic tariffs (2019) (since changed)

Using our electricity monitoring device we were able to record the total energy used each hour for the last 8 months. From this the following was determined:

T93 /kWh off-peakT93 /kWh peakT93 dailyT93 totalT31 /kWhT31 dailyT41 /kWhT41 dailyT31/41 total
$ /year$205$180$386$772$514$347$84$66$1011

To some $239 probably doesn’t sound a lot. And (sadly) the more energy you use, the more you will potentially save. With high fixed daily charges, there’s not much incentive to save more power below a certain amount.

In order to take full advantage of this new tariff you should move as much of your energy use into an off-peak period. Obviously for some households and some power consuming devices, this will be next to impossible. As already mentioned, for most households, there will already be savings to making the switch.

For example a saving may be made by putting a mains timer on the hot water cylinder, and only heating during off-peak times. Some estimates suggest 20% of Australia’s total power generation goes into heating hot water, and may be your 2nd highest energy cost!

A recent Solar Quotes blog post mentions a clever device that can divert excess solar power into any household load instead of getting paid a pittance as an $0.08/kWh feed-in tariff.


8 thoughts on “How we save $240PA by switching from Aurora tariff 31/41 to tariff 93

  1. Hi Andrew,

    I have the same meter and recently changed from T31 and T41 to T93.
    I’m using 1st Energy, not Aurora.

    While on Aurora and then 1st Energy, I could always read the meter as code 101 was T31 and code 201 was T41. Code 140 export solar back to the network.

    Would you happen to know how to read the meter after going to T93 / TOU?
    I have a theory on what the codes now mean but would be interested to hear if you have figured it out?


    1. Hi there, we have a EDMI Atlas 7A meter. On each cycle our energy readings are displayed as follows: 001:import 040:export 101:import 140:export 201:zero 240:zero kWh. I hope that helps but reply if any other info I can provide. We used $3 on heat pump hot water with an extra $7 on general electricity last year.


      1. Thanks Andrew, that does help. Concerning that both my codes 101 and 201 are still increasing considering I’m supposed to be on T93/TOU.
        Congrats on your awesome lack of energy costs!


  2. Have you had a 1st Energy bill yet? Are your 101 & 201 increasing by the same amount each hour and/or each day? Could you turn on a big load like a stove & see which number(s) are going up? I guess with your 1st bill you will see what tariff(s) are being charged for & see for sure if there’s a problem.


    1. I think I will leave it until I get a bill with T93. I can always request the raw data if I think there is any issue. Got two electricians quotes for a timer, one says timer plus contactor, the other says timer only needed. Now to investigate why a contactor could be required!


      1. What is the timer and/or contactor for? Hot water? A 3.6kW element (say) is drawing 3,600W/240V = 15A, so depending on the timer current handling, yes a contactor could be required.


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