Cheapest Time to Charge an EV

Start with the tariff, not a generic clock time

An internet rule such as 'charge after midnight' is only useful if the tariff actually becomes cheaper after midnight. Some plans have a fixed overnight block, others use half-hourly or hourly wholesale-linked prices, and some offer weekend or seasonal periods instead of a simple night rate.

Check the per-kWh rate and the exact start and end times on the electricity contract. The relevant number for the charging calculator is the rate that applies while the vehicle is taking energy, not the household's blended monthly average.

Time-of-use and EV tariffs

Time-of-use tariffs deliberately shift demand away from expensive peak periods. A dedicated EV plan may offer several low-cost overnight hours in exchange for a higher daytime rate. Whether that saves money depends on how much charging and household consumption can be moved into the cheap window.

For an EV driver, the battery is a flexible load because the car is often parked much longer than it actually needs to charge. A scheduled wallbox or vehicle timer can delay the start without requiring the driver to plug in at the exact off-peak time.

Example of off-peak savings

Suppose a 60 kWh battery is charged from 20 to 80 percent at 90 percent efficiency. The wall supplies about 40 kWh. At a peak price of 0.35 per kWh, that session costs 14.00. At an off-peak price of 0.12 per kWh, the same energy costs 4.80.

The 9.20 difference comes entirely from timing and tariff selection; the battery received the same amount of energy. Over repeated weekly charging, the annual effect can be much larger than small differences in charger efficiency.

How long an off-peak window needs to be

Divide the wall energy you need by the usable charging power to estimate whether the session fits inside the cheap period. A 40 kWh session on a 7.4 kW wallbox needs roughly 5.4 ideal hours. On an 11 kW charger it needs about 3.6 hours.

If the cheap window is shorter, the session can either continue at the higher rate or be split across nights. Drivers who rarely arrive with a very low battery may only need to replace a fraction of the pack each night, making even a short off-peak window sufficient.

Smart charging and dynamic prices

Some tariffs change price every hour or half hour. Smart chargers can schedule charging into the cheapest intervals automatically, subject to a required departure time or target state of charge. This can outperform a fixed midnight timer when prices vary significantly from day to day.

Dynamic pricing also creates risk: cheap periods are not guaranteed. Drivers should set a latest completion time or minimum target charge so the car is ready when needed even if the lowest-price window is shorter than expected.

Solar charging changes the calculation

For homes with solar generation, the cheapest energy may be midday rather than overnight. The relevant cost is the opportunity cost of using surplus solar in the car instead of exporting it, plus any import needed when solar output falls below the charging load.

A solar-aware charger can modulate charging power to follow excess generation. Whether that is cheaper than an overnight EV tariff depends on export compensation, import prices and how much surplus solar is actually available.

Common questions

Is midnight always the cheapest time to charge?

No. The cheapest period depends on the tariff. Use the contract's actual time-of-use schedule or dynamic price.

How do I know if an EV tariff is worth it?

Compare the savings on charging during the cheap window with any increase in daytime household rates or additional standing charges.

Can I charge partly in one off-peak window and finish later?

Yes. Most vehicles and smart chargers can schedule charging across multiple periods as long as the car remains connected.