Best time to use electricity
The greenest hours to run the washing machine, dishwasher or car charger, from the grid operator’s carbon intensity forecast, and what timing means for your bill.
When is electricity cheapest?
That depends on the tariff, not just the clock:
- Standard single-rate tariff (including the default price-capped tariff): the same price per kWh at every hour. Shifting your use saves no money, though it can cut emissions.
- Economy 7 and Economy 10: a cheaper rate for a fixed block of hours, mostly at night. The exact hours depend on your region and meter, so check your bill or ask your supplier.
- Smart and agile tariffs: prices change through the day, often every half hour. They tend to be cheapest overnight and when wind and solar output is high, which is when the grid is greenest too.
More in our glossary entries on time-of-use tariffs and demand flexibility. To see what an appliance costs per run, use the electricity cost calculator.
When is electricity greenest?
The forecast above shows carbon intensity: how many grams of CO₂ each kWh carries. It is lowest when wind and solar meet more of demand, often on windy nights and sunny afternoons, and highest on still winter evenings when gas power stations fill the gap. Running a 2-hour washing cycle in the greenest window instead of the dirtiest one can cut its emissions several times over, at no cost on a flat tariff.
Right now, the grid looks like this: live generation mix and carbon intensity.
Frequently asked questions
When is electricity cheapest in the UK?
It depends on your tariff. On a standard single-rate tariff, including the default price-capped tariff, every kWh costs the same at any hour, so timing does not change your bill. On Economy 7 and similar tariffs, a cheaper rate applies for a set block of night hours that varies by region and meter. Smart time-of-use tariffs change price through the day and are usually cheapest overnight and at times of high wind or solar output.
When is electricity greenest?
When the wind is strong or the sun is high and demand is low, typically windy nights and sunny middays. The forecast above shows the expected carbon intensity for each half hour of the next two days.
What does carbon intensity mean?
Grams of CO₂ emitted for each kilowatt-hour of electricity consumed. It rises when gas power stations are running and falls when wind, solar and nuclear cover more of demand.
Why is my region different from the national figure?
Each region draws on a different mix: Scotland has a lot of wind and often very low intensity, while parts of England rely more on gas plants and imports. Enter the first part of your postcode to see your region.
How accurate is the forecast?
It is a model forecast from the National Energy System Operator, refreshed every half hour. It is good for spotting the greener and dirtier periods of the day, but individual half-hour values can be off when the weather forecast changes.
Forecast data: National Energy System Operator, Carbon Intensity API, licensed under CC BY 4.0. Times are UK time.