Charging overnight can cut the cost of running an electric car. But only if your tariff charges less at night—and the saving on the car is bigger than any extra cost for the rest of the house.
Before changing tariff or buying a charger, get your electricity bill out. The useful figures are how much you use, when you use it and what each unit costs. A cheap night rate on its own does not tell you which plan is best.
Does electricity cost less at night in Northern Ireland?
On a flat-rate tariff, charging at midnight costs the same per unit as charging at lunchtime. You need a suitable day/night or time-of-use tariff to pay a different rate.
Northern Ireland has its own electricity market. Check availability at your address rather than assuming an EV tariff advertised for Great Britain applies here. Power NI, for example, offers EV Nightshift and EV Anytime. The former has separate day and night rates; the latter is for charging at any time. That is an example of the choice, not a recommendation that one supplier suits everyone.
The Consumer Council’s Economy 7 comparison is a useful starting point. Compare the daytime rate and daily standing charge as well as the overnight figure. Check payment-method discounts, caps, contract terms and meter requirements with the supplier.
Compare the whole bill, not just the car
Use the electricity drawn from the grid, including charging losses, rather than just the energy added to the car’s battery. Split those units between the proposed day and night periods.
Day/night cost = daytime kWh × day rate + night-time kWh × night rate + standing charges.
Compare that with all the same units at the flat rate, plus that plan’s standing charges. Use prices including VAT. For an annual decision, account for seasonal use and any discount limits; an advertised effective rate may not apply to every unit you buy.
Two examples: the night tariff does not win every time
These are deliberately rounded illustrative rates, not current supplier offers: a flat rate of 32p/kWh, or 38p by day and 18p by night. Both have a 10p daily standing charge. The examples cover 30 days and include the whole household’s grid use, including the car.
| Household use | Flat rate | Day/ | Difference |
|---|---|---|---|
| 300 kWh day + 100 kWh night | £131 | £135 | Night tariff costs £4 more |
| 300 kWh day + 300 kWh night | £195 | £171 | Night tariff saves £24 |
The night-time unit price is lower in both examples. The first household still pays more overall because it buys most of its electricity at the higher daytime rate. The second shifts enough use into the cheaper period to come out ahead. Your bills, mileage and charging routine decide which is closer to your situation.
Check the cheap hours—and the clock change
Do not copy somebody else’s timer settings. Ask your supplier for the hours that apply to your meter and tariff.
As checked on 5 November 2026, Power NI lists EV Nightshift hours as 1am–8am in winter (GMT) and 2am–9am in summer (BST). It says the meter and charger operate independently, so charging times need checking when the clocks change. Other plans may use different windows.
Leave enough time to add the energy you need before leaving. Charging speed depends on the vehicle and installation as well as the number printed on the charger. Ask the supplier about a suitable meter before switching; the charger itself does not change your electricity tariff.
Let the car or charger manage the schedule
Choose a setup that can follow your tariff window and your departure time. Avoid setting conflicting schedules in several places. Follow the instructions for your actual car and charger.
For example, myenergi’s zappi 2.1 instructions use a scheduled boost in ECO or ECO+ mode and tell owners to disable the car’s timer. Those instructions are model-specific; do not assume the same menus apply to a zappi GLO or another charger.
After setup, check the first charging session in the app and against your meter’s cheaper period. A manual boost, an old schedule or a changed departure time can alter when the car draws power.
What changes if you have solar or a home battery?
If the car is at home during daylight, a compatible charger can use surplus solar. Compare that with overnight charging and the export payment you give up by using the electricity yourself. Solar electricity is not automatically the cheapest option in every situation.
A home battery adds another decision: which should receive the energy first—the house, the battery or the car? Ask us to check the controls together. There is little point choosing settings independently and then finding the car is drawing energy you meant to keep for the house.
Our battery storage page covers the systems we install. For the wider costs of a charger, see our home EV charging costs guide.
What to have ready for an installation quote
- Your car model and how far you normally drive.
- Your current tariff, proposed cheap hours and when the car is usually parked at home.
- Where you want the charger and whether you have solar, a battery or plans for a second EV.
Glow Electric installs EV chargers across Belfast and Northern Ireland. We can assess the charger, cable route and controls for your home. Your electricity supplier confirms tariff eligibility and prices. See the chargers and current installation offers, or request an EV installation quote.
Questions about overnight EV charging
Will a smart charger automatically put me on a cheaper tariff?
No. You arrange the tariff with your electricity supplier. The charger or vehicle can then schedule charging within the agreed cheaper hours, subject to its capabilities and settings.
Can a night tariff increase my electricity bill?
Yes. A higher daytime rate or standing charge can outweigh the saving on overnight charging. Compare the cost of all the electricity your household buys, including the car.
Do I need solar panels to charge an EV overnight?
No. Overnight charging can use grid electricity. Solar may offer another charging option when the car is at home in daylight, but it is not required for a home EV charger.