What is an off-peak EV tariff?

Glossary · EV charging

How an off-peak EV tariff works

Electricity demand rises and falls through the day. A time of use tariff charges more in the busy peak periods and less in the quiet off-peak ones.^{[2]Energy Saving Trust, Smart time of use tariffs: all you need to know} An off-peak EV tariff applies that idea to a household with an electric car. Most of these tariffs have separate day and night rates, and the lower rate normally applies overnight so the car can charge cheaply while you sleep.^{[1]Energy Saving Trust, Smart charging for electric vehicles}

You usually need a smart meter. It records when electricity was used, so the supplier can bill the cheap hours at the cheap rate.^{[1]Energy Saving Trust, Smart charging for electric vehicles} The Energy Saving Trust says a smart meter can provide readings every 30 minutes, which is what lets suppliers offer tariffs that follow demand.^{[2]Energy Saving Trust, Smart time of use tariffs: all you need to know}

To benefit, you have to be able to move your use into the cheap hours.^{[2]Energy Saving Trust, Smart time of use tariffs: all you need to know} For an EV driver that is easy to do. Pod Point says certain tariffs offer much cheaper electricity at specific periods, usually late at night, and that you can schedule charging through the charger’s app or the car itself to take advantage.^{[3]Pod Point, Everything you need to know about charging an electric car at home}

Types of tariff and how to charge in the cheap hours

The Energy Saving Trust describes two broad kinds of time of use tariff.^{[2]Energy Saving Trust, Smart time of use tariffs: all you need to know}

Nearly all tariffs are static.^{[2]Energy Saving Trust, Smart time of use tariffs: all you need to know} Some EV tariffs cover only the car’s charging and keep your other household electricity on a separate rate. Many others apply to everything in the home.^{[1]Energy Saving Trust, Smart charging for electric vehicles}

You do not have to own a smart charger to use the cheap hours. With a non-smart chargepoint you can plug in manually during the low-cost period or set the charging time through the car’s dashboard. A smart chargepoint can schedule itself to charge only when electricity is cheapest, and you can override it to charge straight away.^{[1]Energy Saving Trust, Smart charging for electric vehicles} Our page on the smart charger explains the difference.

Example

Omar in Roundhay has a 50kWh car and a smart meter. The Energy Saving Trust’s example for that battery size, with a range of 300 miles, puts a full charge at about £8 on an EV or time of use tariff, about £17 on a standard tariff, about £37 at a public fast charger and about £53 at a public rapid charger.^{[1]Energy Saving Trust, Smart charging for electric vehicles} Those are approximate figures from the Trust, and your own rates will differ. Check the unit rates on your bill or with your supplier.

Omar sets his car to start charging when the cheap rate begins. His evening cooking and washing still happen at the standard daytime rate, so he checks what that rate is before he signs up. For the time a charge takes, see how long it takes to charge at home.

What people get wrong

Many drivers think an EV tariff only changes what the car pays. In most cases it changes the rate for the whole house. The Energy Saving Trust says these tariffs typically apply to all your electricity use, and that if you cannot move your use out of peak times a time of use tariff is unlikely to work for you.

Before switching, ask about the peak and off-peak rates and hours, whether rates change with the season, the contract length and any exit fees. Also ask whether the tariff needs particular equipment such as an EV charger.^{[2]Energy Saving Trust, Smart time of use tariffs: all you need to know} A registered electrician can fit a home charger, but the tariff itself is a matter between you and your supplier. Our EV charger installation page covers the charger side.

The bottom line

An off-peak EV tariff gives you a cheaper unit rate in set low-demand hours, usually overnight, and it works only if your car charges in those hours. You typically need a smart meter, but you do not need a smart charger. The saving is real but depends on the tariff, so compare the day and night rates and the contract terms before you switch.