kWh

Kilowatt-hour — a unit of energy equal to running a 1kW appliance for 1 hour, the basic unit on your electricity and gas bills.

kWh (kilowatt-hour) is energy. kW is power. The difference matters: a 7kW EV charger pulling for 1 hour delivers 7kWh; pulling for 4 hours delivers 28kWh. Your electricity bill prices each kWh consumed (24.67p in May 2026 under the Ofgem cap) and gas bill prices each kWh of gas (5.74p).

Typical UK household figures: 2,700kWh of electricity per year for a low user, 4,200kWh medium, 7,100kWh high. Gas heating adds another 8,000-15,000kWh per year. Adding an EV typically adds 2,500-4,000kWh of electricity. Adding a heat pump replaces gas with around 3,000-6,000kWh of electricity (depending on SCOP and house size).

For battery sizing, work in kWh: a 10kWh battery stores enough to run a typical home overnight or charge an EV by 30-40 miles. For solar sizing, work in kWp. See our solar and battery pages.