When Is Electricity Cheapest? How to Shift Use to Cheap Hours

Wholesale electricity is usually cheapest when demand is low and wind or solar output is high: windy nights and weekends in Denmark, sunny middays in South Australia and Queensland, and quiet overnight hours in Britain. It is usually dearest in the early evening, when people come home, the sun has set and the grid leans on its most expensive plant.

That pattern is a tendency, not a timetable. A calm, cloudy day can turn the usual cheap hours expensive, and a gale can make a weekday evening cheap. The only reliable way to know which hour is cheapest is to look at the published prices for that day, and for a household the answer also depends on what the network and the tax system add to each hour.

Why the cheap hours move

Wholesale prices are set by the most expensive generator needed in each interval. When wind turbines and solar panels, which have almost no fuel cost, meet most of demand, the marginal unit is cheap and the price falls, sometimes below zero. When demand peaks after sunset and gas plants have to run, their fuel cost sets the price. Interconnectors spread these effects: a coupled market imports cheap power from a windy neighbour until the cables are full, and then its price separates.

Denmark: wind first, then the evening

Denmark’s two price zones, DK1 in the west and DK2 in the east, are priced in the European day-ahead auction. Since delivery day 1 October 2025 the auction has cleared in 15-minute intervals, so a Danish day has 96 prices per zone. Wind is large relative to Danish demand, so the cheapest intervals often fall on windy nights and weekends, when demand is low and turbines keep running. Sunny middays in spring and summer can push prices down as well. The early evening is usually the most expensive part of the day, because demand rises as solar output fades.

Because the auction clears the day before, tomorrow’s Danish prices are published in advance. That makes Denmark the easiest of our markets to plan around.

Australia: the midday solar trough

In the National Electricity Market the pattern is shaped by rooftop and large-scale solar. AEMO’s Quarterly Energy Dynamics report for January to March 2026 says negative prices “are more prevalent during daytime hours”, reflecting low operational demand from strong rooftop solar, high wind and solar output and coal plant running at minimum levels. Between 09:00 and 17:00 that quarter, negative prices occurred in 67% of dispatch intervals in South Australia and 26% in Queensland. South Australia had the highest share of negative intervals of any region over the whole quarter, at 31.3%.

The evening peak, which AEMO defines in that report as 16:00 to 21:00, is the reverse. AEMO notes that spot prices generally rise with operational demand, “particularly during evening peaks”. Battery discharge in the evening has grown and is pulling some of those peak prices down, but the shape of the day, cheap at midday and dear at dusk, still holds in most regions.

NEM prices are set every five minutes, and settlement has used five-minute intervals since October 2021, so a single hour can contain very different prices.

Great Britain: overnight and windy days

Britain’s market is settled in half-hours, 48 in a normal day. Demand is lowest overnight and highest in the late afternoon and early evening, particularly in winter. Wind is the main swing factor: a windy night is typically the cheapest period, and a windy day can bring low prices at any hour. We do not publish a cheapest-hours page for Britain; our GB page shows the half-hourly imbalance and market index prices as they are published.

The network tariff can change the answer

For a household the wholesale price is only part of the cost of an hour. In Denmark the local grid company charges a network tariff that varies by time of day. Under the shared model used by grid companies such as N1, households and small businesses connected to the low-voltage network, called C customers, pay according to three periods:

Period	Hours (local time)	Name in Danish	Seasons
Low load	00:00–06:00	Lavlast	Summer (April–September) and winter (October–March)
High load	06:00–17:00 and 21:00–24:00	Højlast	Both seasons
Peak load	17:00–21:00	Spidslast	Both seasons

N1 describes the aim plainly: there is money to save by moving consumption out of the 17:00–21:00 peak, and charging an electric car or running a dishwasher in the peak becomes more expensive. The rates themselves differ between grid companies and between summer and winter, and Energinet publishes every company’s tariffs, hour by hour, in the DatahubPricelist dataset on Energi Data Service.

The practical consequence is that the cheapest wholesale hour is not always the cheapest hour on the bill. A low spot price at 18:00 sits inside the peak tariff, so a slightly higher spot price at 22:00 or after midnight can be cheaper in total. Our Danish-language pages at /da/elpriser/ show both the spot price and a total price with tariffs, taxes and VAT; the English cheapest-hours pages show the wholesale price only.

Other countries add their own layers. In Britain, Ofgem’s price cap is built from wholesale costs, network costs, policy costs, supplier costs and VAT, and most of those do not vary by hour unless a supplier offers a time-of-use or dynamic tariff.

How to use our cheapest-hours pages

The cheapest-hours hub lists the cheapest hour today for Denmark’s two zones and five Australian regions, and each market has its own page with an hour-by-hour table for today and, once published, tomorrow, together with the cheapest single hour and the cheapest block of consecutive hours.

A few conventions are worth knowing before you plan with them:

• An hour is a local clock hour of the market’s own calendar day. On a clock-change day there are 23 or 25 hours.
• In Denmark, each hour’s price is the average of the four 15-minute day-ahead prices inside it. Tomorrow’s hours appear once Energinet publishes the auction results.
• In Australia, hours already past use AEMO’s five-minute dispatch prices. Hours still to come use AEMO’s 30-minute pre-dispatch prices and are labelled “forecast by AEMO”. Pre-dispatch is revised as generators change their offers, so a future hour’s price can move before it arrives.
• Missing data stays missing. An hour without published prices is left empty rather than filled with an estimate.

The cheapest block is useful for loads that run for several hours, such as charging a car overnight. The single cheapest hour suits short loads.

Which loads can move

Only some household consumption is flexible. The loads that shift most easily are those that store energy or simply need to be finished by a certain time:

Electric vehicle charging is usually the largest flexible load in a home. A car plugged in overnight can often be set to charge in the cheapest block before morning.

Laundry and dishwashers can be started on a delay timer so that they run after the evening peak or during a cheap midday period.

Hot water from a heat pump or electric tank can be heated in advance and stored, which moves energy use away from the peak without changing when hot water is used.

Home batteries charge in cheap hours and discharge later, which is the same arithmetic that AEMO sees at grid scale.

Cooking, lighting and most space heating are much harder to move, and comfort and safety come first: appliances should not be left running unattended where a manufacturer advises against it.

When cheap hours do not save money

The wholesale price changes what a household pays only if its contract passes that price through, as with an hourly variable or dynamic tariff. On a fixed or capped tariff, shifting use to a low wholesale hour does not lower that month’s bill, although a time-of-use network tariff, as in Denmark, may still reward avoiding the peak. Check how your own contract is priced before relying on any hourly figure.

Our figures are provisional, come from the operators’ own publications and are not advice. A negative wholesale price is a genuine market result, but it is not a payment that reaches a household unless its contract is built to pass it on.