Charging an electric vehicle at home is one of the most cost-effective ways to power your EV in the UK. Costs depend on the EV’s battery size (in kWh), electricity tariff rates, charger efficiency and charging habits.
Battery Size: Measured in kilowatt-hours (kWh), this determines how much energy is needed. Common battery sizes include:
Small: 40kWh (e.g., Nissan Leaf).
Medium: 60kWh (e.g., Tesla Model 3).
Large: 100kWh (e.g., Tesla Model S, Audi e-tron)
Electricity Tariff: Rates vary by provider and plan. Octopus Energy’s EV-focused tariffs offer some of the lowest rates:
Intelligent Octopus Go: Intelligent Octopus Go: ~7.5p/kWh off-peak (core 11:30 PM–5:30 AM window, with smart charging automatically scheduled for cheapest/greenest times; whole home benefits during off-peak), ~30–32p/kWh peak (2026 rates, per Octopus Energy; off-peak capped at up to 6 hours smart charging per day since early 2026 changes).
Octopus Go: ~9p/kWh off-peak (fixed 12:30 AM–5:30 AM window), ~31p/kWh peak (standard predictable overnight tariff, no smart scheduling required).
Standard Variable Tariff: ~27.7p/kWh (UK average electricity unit rate under Ofgem price cap for January–March 2026; drops to ~24.7p/kWh from April 2026 onward).
Charger Efficiency: 7kW and 22kW chargers have ~85–90% efficiency due to heat losses, so a 60kWh battery may require ~66–70kWh from the grid.
Charging Habits: Smart chargers optimise for off-peak rates, reducing costs. Charging during peak hours increases expenses.
Charger Power:
7kW: Standard for UK homes with single-phase power, charging a 60kWh battery in ~8–9 hours.
22kW: Requires three-phase power, charging faster (~3–5 hours for 60kWh, if EV supports 22kW AC), but costs are similar per kWh unless time-of-use tariffs vary.
Comparison to Petrol/Diesel Costs
EV Charging: A 60kWh EV charged 10 times/month on Intelligent Octopus Go costs £45/month (at 7.5p/kWh off-peak). At 3 miles/kWh efficiency, this covers 2,160 miles/month (well above the UK average of 600–700 miles/month, but great for higher-mileage drivers).
Petrol Car: A car averaging 40 mpg with unleaded petrol at £1.37/litre (UK average, March 2026 per RAC/government data) costs £162/month for the same 2,160 miles (7.5p/mile vs. 2.1p/mile for the EV).
Savings: EVs save 60–75% on "fuel" costs compared to petrol equivalents, even more pronounced with rising pump prices.