When power is cheap depends on your tariff
On a single-rate (flat) plan the answer is simple: electricity costs the same at 2am as it does at 6pm, so timing does not change your bill. But a large and growing share of Australian homes are now on a time-of-use tariff, where the price per kWh changes through the day. On those plans, when you use power can matter almost as much as how much you use.
A time-of-use tariff splits the day into peak (the expensive window, typically weekday late afternoon and evening when the grid is busiest), off-peak (the cheapest, usually overnight and often weekends), and shoulder (the times in between). The exact hours are set by your local network, not just your retailer, so they differ by state and area — always check your own bill for the precise windows.
Off-peak, and the new "solar sponge" middle of the day
Traditional off-peak is overnight — commonly from late evening until early morning. That is when running the dishwasher, washing machine, dryer, pool pump or an EV charger costs least on a time-of-use plan. Controlled-load tariffs for hot water and pool pumps push those loads into the small hours automatically at a very low rate.
A newer wrinkle is the daytime "solar sponge" or "solar soak" period. Because rooftop solar now floods the grid in the middle of the day, several networks have introduced very cheap daytime rates — sometimes cheaper than overnight — to encourage households to use power when it is abundant. If your plan has one, the middle of the day can be the cheapest time of all to run big appliances, even without your own panels.
How to shift load without changing your life
- Find your windows: check your bill or your retailer app for your exact peak, shoulder, off-peak and any solar-sponge hours — they vary by network.
- Use timers and delay-start: set the dishwasher, washing machine and dryer to start in the off-peak or solar-sponge window rather than during the evening peak.
- Automate the big loads: put hot water and pool pumps on controlled load or a timer so they run at the cheapest time without you thinking about it.
- Charge overnight: schedule an EV or battery charge for the off-peak window — it is often the single biggest load you can move.
- Avoid stacking the peak: try not to run the oven, air conditioner, dryer and pool pump all at once in the late-afternoon peak.
Is a time-of-use plan even right for you?
Time-of-use only saves money if you can genuinely move load into the cheap windows. A household that is out all day and uses most of its power in the evening peak may actually pay more on time-of-use than on a flat rate. There is no universal winner — it depends entirely on your pattern.
EnergySorted settles the question by costing both structures against your real usage. It applies your actual peak and off-peak split across 16,000+ plans, takes no retailer commission, and shows whether a flat rate, a time-of-use plan or a solar-sponge tariff genuinely costs you least. Its off-peak and time-of-use optimisation view highlights how much you could save by shifting specific loads.