When is electricity cheapest in Perth? Synergy's tariff hours explained

"When is electricity cheapest?" is one of the most common questions Perth households ask after getting a high bill. The answer isn't universal — it depends entirely on which Synergy tariff you're on.

Here's a clear breakdown.

On A1 (the default flat rate): there is no cheaper time

Most Perth households are on Synergy's A1 Home Plan — the flat rate tariff. From 1 July 2026, A1 charges 33.26c/kWh around the clock.

There are no peak hours. There are no off-peak hours. The same rate applies at 2am, 2pm, and 6pm.

If you've heard that running the dishwasher late at night is cheaper, that advice came from older tariff structures or from states with time-of-use metering (like New South Wales or Victoria). It doesn't apply to Synergy A1 customers. Your timing doesn't change what you pay.

The only relevant decision for A1 customers is whether to switch to Midday Saver, where timing does matter.

On Midday Saver: cheapest between 9am and 3pm

Midday Saver is Synergy's time-of-use tariff. It has three price periods:

| Period | Hours | Rate (from 1 July 2026) | |---|---|---| | Super off-peak | 9am–3pm | 8.85 c/kWh | | Off-peak | 9pm–9am | 24.34 c/kWh | | Peak | 3pm–9pm | 55.33 c/kWh |

The 9am–3pm window is dramatically cheaper — 73% below the A1 flat rate. That's the sweet spot for shifting large loads.

The 3pm–9pm window is the most expensive — 66% above A1. Every kWh used in that window on Midday Saver costs more than on A1.

What to shift to the 9am–3pm window on Midday Saver

| Appliance | Typical draw | Cost at 8.85c | Cost at 55.33c | |---|---|---|---| | Washing machine (cold) | 0.5 kWh/cycle | 4c | 28c | | Clothes dryer | 3 kWh/cycle | 27c | $1.66 | | Dishwasher | 1.5 kWh/cycle | 13c | 83c | | Pool pump (1.0kW, 3hr) | 3 kWh | 27c | $1.66 | | Hot water element (3.6kW, 1hr) | 3.6 kWh | 32c | $1.99 |

Running the dryer during the 9am–3pm window instead of 5pm saves $1.39 per cycle. Over 200 cycles a year, that's $278.

On EV Add-On: cheapest overnight

If you've added the Synergy EV Add-On to your plan, you get a discounted overnight rate for EV charging:

• Overnight EV rate (11pm–7am): 19.92c/kWh

This applies to a dedicated EV circuit, not your whole home. It's designed specifically for overnight slow charging (Type 2 / 7kW AC charger). At 19.92c/kWh, charging a 60kWh battery from 20% to 100% costs $9.56.

If you also have solar and a compatible charger, you can configure daytime solar charging for effectively zero ongoing electricity cost — but the EV Add-On overnight rate is still the backup for days when solar doesn't cover the charge.

Solar: the ultimate "cheap time"

If you have solar panels, the cheapest electricity in Perth isn't a tariff rate at all — it's free midday solar generation.

Perth averages 5 peak sun hours per day. A 6.6kW system generates roughly 33 kWh on a clear day, most of it between 10am and 2pm. That generation costs you nothing marginal (the system has already been paid for in the payback calculation).

The most valuable thing a solar household can do is self-consume as much of that midday generation as possible rather than exporting it to the grid at DEBS rates (10c/kWh peak, 2c/kWh off-peak).

Running the dishwasher, dryer, pool pump, or pre-cooling the house while the sun is shining is worth 33.26c/kWh in avoided grid import — whether you're on A1 or Midday Saver.

On Midday Saver with solar, the calculation gets even more favourable: you're avoiding the 55.33c peak rate in the late afternoon by pre-cooling or running loads earlier in the cheap window.

How to find out which tariff you're on

Log in to My Synergy and check your plan details. Alternatively, your bill shows the rate code on the first page — A1 is the most common, but if you see "Midday Saver" you're on the time-of-use plan.

If you're not sure whether switching would save you money, the calculation depends on how much of your usage falls in the 3pm–9pm peak window. Most households don't know this number off the top of their head.

Upload your Synergy bill to BillWise → and we'll calculate which tariff is cheaper for your specific usage pattern — including your solar generation profile if you have it — and show you exactly how much you'd save by switching or by shifting specific appliances.

Quick reference: Synergy tariff hours in Perth

| Tariff | Cheapest time | Rate | Most expensive time | Rate | |---|---|---|---|---| | A1 (flat) | Any time | 33.26c/kWh | Any time (same) | 33.26c/kWh | | Midday Saver | 9am–3pm | 8.85c/kWh | 3pm–9pm | 55.33c/kWh | | EV Add-On overnight | 11pm–7am | 19.92c/kWh | (applies to EV circuit only) | — |

Rates are Synergy published rates effective 1 July 2026. All figures in Australian cents per kilowatt-hour (c/kWh) including GST.