When is the cheapest time to use power in NZ?
The cheapest time to use power in New Zealand has a frustrating answer for most people: there isn't one. The large majority of NZ households are on a flat-rate plan, where a unit of electricity costs the same 42-or-so cents at three in the afternoon as it does at three in the morning. Running the dryer at midnight saves you nothing, because the meter cannot tell the difference.
But that is only the default, and the default is changing. Under new Electricity Authority rules, every major retailer must now offer a time-of-use option. On one of those plans the rate genuinely changes through the day - and then when you use power starts to matter a lot. This guide is about how to make timing pay, and it starts with checking which kind of plan you are actually on.
Flat rate vs time-of-use
A flat-rate plan charges one price per kWh around the clock. Simple, predictable, and completely indifferent to timing. If this is you, no amount of midnight laundry helps the bill - your lever is choosing the right plan, not the right hour.
A time-of-use plan charges different rates at different times. The shape most New Zealanders will meet has two peaks a day, which surprises people who assume it is just "evenings":
| Band | When | Rate |
|---|---|---|
| Peak (morning) | 7-11am | ~33c |
| Peak (evening) | 5-9pm | ~33c |
| Shoulder / off-peak | 11am-5pm, 9-11pm | ~24c |
| Night | 11pm-7am | ~16c |
Exact windows and prices vary by network and retailer - some run a shorter morning peak, and weekends are usually off-peak all day - but the twin-peak shape is standard, and it is set by the local network rather than invented by each retailer. Note the spread: night power can be around half the peak price. That is the opportunity.
Whether a time-of-use plan beats a flat one depends on your household. We break down the trade-off in detail in are day/night power plans worth it in NZ? - the short version is that they reward households that can push flexible load into the cheap bands, and quietly punish those that cannot.
Ripple control: the shifting you already have
Many NZ homes already do some off-peak shifting without knowing it, through ripple control. Your lines company - the distributor that owns the wires, not the retailer that bills you - can briefly switch your hot water cylinder off during peak demand and let it reheat later, when the network is quieter. The cylinder holds enough hot water that you rarely notice.
Just over half of New Zealand's electricity consumers are on ripple-controlled connections, and collectively that controlled load is a significant share of national peak demand. It is one reason hot water, despite being a quarter to a third of the bill, is less of a timing problem than it looks. Ripple is slowly being replaced by smart-meter based control, but for now it is quietly working in the background of a great many homes.
What to shift - and what not to bother with
If you are on a time-of-use plan, the goal is to move large, flexible loads out of the two peak windows and ideally into the night band. The best candidates:
- EV charging. By far the biggest win. An EV charged overnight instead of plugged in at 6pm can roughly halve its charging cost. Set the car or charger to start after the night rate begins.
- Dishwasher. Use the delay-start timer to run it overnight rather than straight after dinner in the evening peak.
- Washing machine and dryer. Same idea - a clothes dryer is a heavy load, so shifting a wash-and-dry off-peak adds up over a week. Watch the morning peak too: a 7.30am load now lands in an expensive window.
- Spa heating. A spa heats whenever it drifts below temperature, so a controller that concentrates that top-up overnight moves a big load cheaply.
Just as important is what not to twist yourself over. Do not eat dinner cold or sit shivering to dodge the peak - cooking and heating are comfort loads you use when you need them, and the few cents saved is not worth the misery. Shift the things that genuinely do not care what time they run; leave the rest alone.
The worked saving
Take the rates above. An EV adding 40 kWh a week, moved from the evening peak (~33c) to the night band (~16c), saves 40 × $0.165 = $6.60 a week, or about $29 a month from that one change. Shift it only as far as the shoulder rate and the saving is closer to $16 a month.
Across a whole household, Powerswitch reports that people who actively make the most of a time-of-use plan typically save around 20% on their bill - on a $200-230 monthly bill, roughly $40-46. But that word "actively" is doing real work. Powerswitch also warns that a household which moves to time-of-use and keeps using power at the same times can end up worse off than on a flat rate, because the peak rate is higher than the flat rate it replaced. The plan does not save money; changing your habits does.
Check it against your own bill
Timing only pays once the plan is right, so start there. Compare time-of-use and flat plans at your address on Billy or Powerswitch, and use the power bill calculator to see which of your appliances are big and flexible enough to be worth shifting in the first place. For most homes it comes down to the car, the dishwasher and the laundry.
Related guides
- Are Day/Night power plans worth it in NZ? - whether time-of-use beats flat for you
- EV home charging cost in NZ - the load that gains most from off-peak
- How to switch power company in NZ - moving to a plan that suits your hours