spothours

How to move the big loads to the cheap hours

Written and reviewed by Damian Bazzano · About the author · Last reviewed 2026-08-20

Knowing that electricity is cheapest at 03:00 is no use if you are asleep at 03:00. This page is about the mechanism rather than the price: which loads are large enough to be worth moving, the three ways to make a machine start without you standing in front of it, and why the obvious answer — a smart plug — usually does not do what people expect.

First: does any of this reach your bill?

The hourly price only reaches your bill if your contract passes it through. That means the regulated PVPC tariff in Spain, or a dynamic or spot-linked contract in the Netherlands, Germany, Sweden, Denmark or Finland. On a fixed-price contract you pay the same for a kilowatt-hour at 03:00 as at 20:00, and moving a wash changes the energy line of your bill by nothing at all.

There are two exceptions worth knowing, because they catch people out in the opposite direction. In Denmark the grid tariff itself is time-banded: the evening peak band costs several times the night band, and that applies whatever your energy contract says. Spain works the same way through the 2.0TD access tolls, where the P1 peak and the P3 valley are set nationally. In both countries a household on a fixed energy price still pays measurably less for electricity used at night.

If you are on a fixed contract in a country without time-banded grid charges, the honest advice is to settle the contract question before automating anything. Everything below assumes the price you pay actually moves.

Start with the biggest loads, not the most visible ones

The percentage saving is the same for every appliance — it is just the gap between two prices. The amount of money is not, because it scales with the kilowatt-hours involved, and those differ by a factor of several hundred across a normal home.

A useful cut-off is one kilowatt-hour per run, repeated regularly. Above it, automation pays for the attention it costs. Below it — the kettle, the toaster, the phone charger — the entire annual difference between the best and worst hours is small change, and any advice that tells you to time your kettle is padding.

See what each of these costs right now in your area →

1. The delay timer already built into the machine

Almost every washing machine, dishwasher and tumble dryer sold in the last fifteen to twenty years has one. It is usually marked with a clock icon and called delay start, delayed start, or end time. You load the machine, choose the programme, set the delay, and walk away.

One detail decides whether it works for you: machines differ on what they are delaying. Some count the hours until the cycle begins; others let you set the time the cycle should finish. Setting a three-hour delay on a machine that means "finish in three hours" puts the wash somewhere quite different from where you intended, and on a winter evening that difference is the peak. It is worth reading that one line of the manual once.

This method costs nothing, needs no accessory, nothing to charge or pair, and does not stop working when a cloud service is retired. It is the right answer whenever it is available. Its only real limitation is that you set it by hand each time — which matters less than it sounds, because tomorrow's prices are already published by the time you are loading the machine in the evening.

Check tomorrow's prices before you set the timer →

2. A robot button pusher, for machines without a timer

A robot button pusher — SwitchBot Bot, Fingerbot and similar — is a small battery-powered device that sticks next to the start button with double-sided tape and physically presses it at a scheduled time. It changes nothing inside the appliance, which is what makes it appealing.

It also has three conditions, and all three have to hold:

This is a workaround, and it is worth being clear about that. If your machine has a delay timer, use the delay timer.

3. A smart plug — which usually will not do what you want

This is the question we get asked most, and the answer is generally no. A smart plug switches power on and off. It does not press start. On a modern electronic washing machine, restoring power gives you a machine that is switched on and waiting for someone to press a button — the cycle does not begin, and you come down in the morning to dry laundry sitting in the drum.

There is a thirty-second test that settles it for your machine. Load it, start a cycle, pull the plug out mid-wash, and plug it back in. If the drum picks up where it left off, your machine resumes after a power interruption and a smart plug will work. If it sits there lit up and waiting, it will not. Old machines with a mechanical dial almost always resume, because the dial is the programme and it never lost its place. Most electronic machines do not.

Where a smart plug genuinely is the right tool is anything that is simply a heater or a motor with no start button — where power on means running. An electric water heater, a heated towel rail, a dehumidifier, a pool pump, an oil-filled radiator. For those, a plain mechanical socket timer costing a few euros does the same job with nothing to configure.

4. The appliance's own scheduling, or a spot-price integration

Newer appliances, most wallboxes and nearly all heat pumps have their own scheduling, and the better ones can read the day-ahead price directly rather than being told a fixed hour. Home Assistant and similar systems will do the same thing across brands, and several suppliers offer smart charging that decides the hours for you.

The practical point: if you are going to spend money on this, spend it on connectivity that is built into the appliance rather than bolted onto the outside of it. A car that charges on a schedule it worked out from tomorrow's prices is doing the whole job. A robot finger taped to a button is doing an impression of it.

Washing machine and dishwasher

Between them these are the loads people most want to shift, and at roughly 0.7 and 0.9 kWh a cycle, each individual run saves small money. The reason to do it anyway is that the delay timer is free and you run these machines a few hundred times a year.

Two practical notes. Detergent sitting in a wet dispenser drawer for eight hours can clump or leach away, so a shorter delay is better than a maximum one, and capsules placed in the drum avoid the problem entirely. And wet laundry left in a sealed drum for hours starts to smell — so if your machine sets an end time rather than a start delay, aim for it to finish shortly before you get up rather than in the middle of the night.

Tumble dryer

At around 2.5 kWh a load, and more for an older vented model, the dryer is the largest of the everyday household loads and the one where shifting an hour is worth the most. A heat-pump dryer uses roughly half as much for the same laundry, which is a bigger saving than any amount of clever timing — worth knowing when the current one dies.

Cleaning the lint filter every cycle also affects consumption more than most people expect, because a blocked filter makes the machine run longer for the same result. And of all the appliances on this page, the dryer is the one fire services are most emphatic about not leaving running unattended.

Electric water heater (storage tank)

A hot water tank is the best load-shifting opportunity in most homes and the one people overlook. It is already a battery: it stores heat, and it does not care when that heat was put in. Heating overnight and coasting through the day uses the same kilowatt-hours at a lower price, and unlike a washing machine it needs no start button — a plain socket timer or a smart plug switching the supply is enough, provided the circuit is rated for it and the connection is a plug rather than a fixed wiring point.

Two caveats, both real. Legionella bacteria grow in warm water, and the standard defence is letting the tank reach around 60 °C regularly — so do not trim the heating window so tightly that it never gets there. And a poorly insulated old tank loses heat all day; if it is cold to the touch on the outside, an overnight-only schedule can lose more in standing heat than the cheaper hours save.

None of this applies to instantaneous or on-demand water heaters. They make hot water at the moment you open the tap, they store nothing, and there is no timing to shift.

Electric car

This is the single largest prize on the page, by a distance. A 50 kWh charge moved from the evening peak to the cheapest hours of the night can save more in one night than a year of careful dishwasher timing. If you own an electric car and do nothing else on this list, do this one.

Use the scheduling built into the car or the wallbox, or a charger that follows the day-ahead price directly. Both are designed for exactly this and both handle the awkward cases — a departure time, a battery that is already nearly full — better than a fixed clock would.

One firm warning: never put a wallbox, a charging cable or a portable charger on a smart plug or a mechanical socket timer. A wallbox draws several kilowatts continuously for hours, far beyond what a plug-in accessory is built for, and even slow charging from a domestic socket runs at close to that socket's limit for most of a night. This is a genuine fire risk, not a warranty technicality.

Heat pump, air conditioning and electric heating

Heating and cooling are not delayed, they are moved. The building itself is the store: run the system a little harder while electricity is cheap, let the temperature drift back during the expensive hours. A well-insulated home holds its temperature for hours; a draughty one does not, and there the technique barely works.

Keep the offsets modest — one or two degrees. Two things push back against being clever here. A heat pump becomes less efficient the harder you push its flow temperature, so a large pre-heat can burn more kilowatt-hours than the price gap saves. And a home that swings three degrees over an evening is simply unpleasant to sit in, which is a cost that does not show up on the bill.

If your system has a proper programmable thermostat, that is the tool for this, not a plug. Most heating systems are wired in rather than plugged in, and a heat pump in particular should never have its supply interrupted by an accessory.

What cannot be shifted at all

Fridges and freezers decide their own duty cycle from their own thermostat, and cutting their power to dodge an expensive hour risks the food inside for a saving of a few cents. Standby consumption across a house is worth attacking, but it is a constant, not something that can be moved to a better hour. In both cases the money is in the appliance itself — a more efficient fridge, a switched power strip — not in timing.

Before you automate anything: the fine print

How much is this actually worth?

Worth being blunt about, because a lot of writing on this subject is not. Moving one dishwasher cycle a day from an expensive hour to the cheapest one saves the price gap on about 0.9 kWh, three hundred and sixty-five times. On a typical day in a market like Spain that gap is often ten to fifteen cents a kilowatt-hour, which puts the year at somewhere around twenty to forty euros. A washing machine, run less often, is worth less than that.

Now run the same arithmetic on an electric car taking 50 kWh a week: the same price gap, applied to fifty times the energy, lands in the low hundreds of euros a year. A water heater using five kilowatt-hours a day sits between the two. This is why the order in this guide is the order it is — one evening spent setting up the car and the water heater is worth more than a year of diligence with the dishwasher.

These are illustrations, not promises. The gap between the cheapest and dearest hour varies enormously from day to day and market to market, and on a calm winter day it can be small enough that none of this matters.

Work it out for your own area and today's prices →

Common questions

Will a smart plug start my washing machine?
Usually not. A smart plug restores power; it does not press start, and most electronic machines wait for a button after a power interruption. Test yours by unplugging it mid-cycle and plugging it back in — if the wash resumes on its own, a smart plug will work.
Does any of this help if I am on a fixed-price contract?
Not on the energy part of your bill, which is the same at every hour by definition. But in Denmark and Spain the grid tariff itself is time-banded, so electricity used at night genuinely costs less regardless of your supplier contract.
When do I know tomorrow's prices?
The day-ahead auction closes at 12:00 CET and the results are normally published between 13:00 and 14:00. From that moment tomorrow's curve is fixed and public, which is why the evening before is the right time to set a timer.
Is it safe to run a washing machine overnight?
Fire services in several countries advise against running these machines unattended, and that advice is not really about electricity prices. Setting the cycle to finish shortly before you get up captures most of the saving without leaving a machine running while the house is asleep.
My machine has no delay timer and its buttons are touch-sensitive. What now?
Robot button pushers cannot operate a capacitive panel, so the honest answer is that this machine cannot be automated from the outside. Your options are to run it manually during a cheap window — a weekend afternoon, or the middle of the day in a market with a lot of solar — and to make a delay timer a requirement when you replace it.

See today’s hourly prices →

Spot a figure that looks wrong? Tell us. Corrections and the sources behind every tax and grid assumption are listed on the methodology page.