Time-of-Use Electricity Tariffs Explained (And How to Beat Peak Prices)

A time-of-use tariff charges you a different rate for electricity depending on the time of day you use it. Power costs the most during peak periods (usually the evening), less during off-peak (usually overnight), and least during the middle of the day when solar floods the grid. The trick to a lower bill is simple: use less power when it is expensive, and more when it is cheap. Solar and a home battery let you do exactly that automatically.

What is a time-of-use tariff?

On an older flat-rate tariff, every unit of electricity (every kilowatt-hour, or kWh) costs the same no matter when you use it. A time-of-use tariff breaks the day into pricing windows and charges a different rate in each one. The idea is to reward you for shifting your usage away from the hours when the grid is under the most strain.

Most time-of-use plans have three windows: peak (the priciest), off-peak (the cheapest overnight), and a shoulder or solar-sponge period in between. The exact times and rates are set by your network and your retailer, so two homes in different suburbs can be on slightly different schedules.

The golden rule of a time-of-use tariff: run the big power users when electricity is cheap, and avoid the grid when it is expensive.

When are peak, off-peak and solar-sponge times?

Times vary by network and retailer, and they can change (South Australia's network updated its time-of-use periods in mid-2025). As a general guide, most Australian households on a time-of-use plan see something like this:

• Peak — typically weekday evenings, when everyone gets home, cooks and switches on heating or cooling. This is the most expensive window.
• Off-peak — usually the small hours of the morning, when demand is lowest. This is the cheapest window for drawing from the grid.
• Solar sponge / daytime — often a cheap block in the middle of the day, designed to soak up the flood of rooftop solar on the grid.

Do not treat those as your exact times. The only reliable source is your own electricity plan — check your bill or your retailer's rate sheet for the precise peak and off-peak hours that apply to your address.

How is it different from a flat-rate tariff?

A flat rate is predictable but blunt: you pay the same whether you run the dryer at 2pm or 7pm. A time-of-use tariff is sharper. It can save you real money if most of your usage naturally lands in the cheaper windows, or if you can move it there. It can cost you more if your household runs hard through the peak evening block and you do nothing to change that.

That is why the tariff you are on matters less than what you do with it. The households that win on time-of-use are the ones that shift load into the cheap hours — and the easiest way to shift load is with solar during the day and a battery at night.

How does a solar battery beat peak prices?

This is where a battery earns its keep. Your solar panels generate the most power in the middle of the day — exactly when grid electricity is cheap and your feed-in return for exporting is usually low. Instead of selling that cheap daytime energy back for a small return, a battery stores it. Then, when the expensive peak window hits in the evening, your home runs on stored solar instead of buying costly grid power.

This is called load-shifting, and it is the single biggest lever on a time-of-use tariff. You are moving your own free solar from the middle of the day into the priciest hours of the night — so that the peak rate barely touches you. A well-sized battery can carry a typical home through the evening peak and into the night.

Storing your solar to use during the evening peak is usually worth far more than exporting it — because you avoid the highest price of the day instead of selling at the lowest.

Can you save on a time-of-use tariff without a battery?

Yes — and you should start here even before you buy anything. If you are on a time-of-use plan, small habit changes add up:

• Run the dishwasher, washing machine and dryer during the cheap daytime solar-sponge window, not in the evening peak.
• Pre-cool or pre-heat the house with your air conditioner in the afternoon so it coasts through the peak.
• Charge your EV overnight in off-peak or during the day on solar, never during the evening peak.
• Heat your hot water in the middle of the day — a heat-pump hot water system on a timer is ideal for this.

Solar panels alone already help, because every unit you self-consume while the sun is up is a unit you do not buy from the grid at that time — and daytime is when you can run your big appliances on that free power instead of drawing from the grid. Adding a battery takes it further by covering the evening peak, when the panels have stopped and prices are highest.

Is a time-of-use tariff worth it for you?

It depends on your usage shape. If you are home during the day, have solar, or can move your big appliances into the cheap windows, a time-of-use tariff can work strongly in your favour. If your life runs on the evening peak and you cannot shift it, a flat rate may suit you better — or it may be the nudge to add solar and storage so you control when you use the grid.

The best way to decide is to look at your actual usage against your options. Start with our solar battery page to see how storage fits an all-day, all-night plan, and for current incentives and finance see rebates and finance — these change over time and vary by state, so we keep that page up to date rather than quoting figures that go stale.

Frequently asked questions

What does time-of-use mean on my electricity bill?

It means you are charged different rates for electricity depending on the time of day. Peak periods (usually weekday evenings) cost the most, off-peak (usually overnight) costs the least, and there is often a cheaper daytime window. Your bill or retailer rate sheet lists the exact times for your address.

When is off-peak electricity cheapest?

For most time-of-use plans the cheapest grid power is overnight, in the small hours of the morning, with a second cheap block often in the middle of the day when rooftop solar is abundant. Exact times vary by network and retailer, so always confirm against your own plan.

Does a solar battery help on a time-of-use tariff?

Yes, strongly. A battery stores your cheap daytime solar and releases it during the expensive evening peak, so you avoid buying power at the highest rate. This load-shifting is usually the single biggest saving a battery delivers on a time-of-use plan.

Should I switch to a time-of-use tariff?

It suits you if you have solar, are home during the day, or can move big appliances into the cheaper windows. If your household runs hard through the evening peak and you cannot shift it, a flat rate may cost less. Compare your actual usage before deciding.

Can I save money on a time-of-use tariff without solar?

Yes. Run appliances like the dishwasher, washing machine and dryer in the cheaper daytime or overnight windows, pre-cool the house before the peak, and heat hot water in the middle of the day. These habit changes cut your bill even before you add solar or a battery.