kWh / Kilowatt-hour

A kilowatt-hour, or kWh, is a unit of energy. It is the amount of energy used, generated, stored or delivered when a power level of 1 kW is sustained for one hour. That makes it different from kW, which describes the rate of use, generation, charging or discharge at a particular moment. Electricity bills, solar export records, smart-tariff apps, battery datasheets and EV charging sessions use kWh because they are counting a quantity of energy over time. For example, a charger delivering 5 kW for two hours would deliver about 10 kWh before charging losses and any vehicle or charger limits. When comparing documents, check whether the figure is nominal capacity, usable capacity, metered consumption or delivered energy because those labels can describe different quantities.