Australian electricity retailers offer two main residential tariff structures: flat-rate (one price per kWh regardless of time) and time-of-use (ToU) (different prices for peak, shoulder, and off-peak periods). ToU peak is typically 3-9pm weekdays at 35-50c/kWh; shoulder is 7am-3pm and 9pm-10pm at 25-30c/kWh; off-peak overnight at 10-18c/kWh.

ToU wins if you can shift discretionary loads to off-peak: dishwashers and washing machines on timer overnight, EV charging overnight, pool pumps during solar-feed daytime, hot water on overnight tariff. ToU loses badly if you have evening-heavy usage — working from home with day-time computer/cooking/lighting, kids home from school using devices, evening cooking and entertainment, climate control during peak. Households with solar PV almost always win on ToU because daytime usage is supplied from solar (effectively free) and grid imports are mainly off-peak overnight.

To estimate your usage split: most smart-meter portals show a peak/shoulder/off-peak breakdown over the past quarter. WFH households typically have 25-40% in peak; weekday-out households 10-20%. The calculator above lets you plug in your specific split and your retailer's specific rates. The right answer is your real numbers — don't trust generic 'ToU saves money' advice without checking your specific use pattern. For solar payback see our Solar / Battery Payback Calculator.