GLOSSARY

kW versus kWh

A kilowatt (kW) is power, the rate a device draws; a kilowatt-hour (kWh) is energy, power sustained over time. A 150 W bulb draws 0.15 kW and consumes 0.15 kWh in an hour. In a parking facility:

kW POWER · THE RATE How fast energy moves like a tap’s flow rate kWh ENERGY · THE AMOUNT How much moves over time like water collected in a bucket kWh = kW × hours · e.g. an 11 kW charger for 8 h = 88 kWh
Power (kW) is the rate energy flows; energy (kWh) is how much is delivered over time. Chargers are rated in kW; utility bills and battery capacity are measured in kWh.
  • Chargers and service loads are sized in kW; utility bills and charging fees are settled in kWh.
  • The paper’s planning rate: about 3.1 miles of range gained per kWh delivered for current BEVs.

Considerations

  • Selling energy by the kWh makes the charger a commercial measuring device subject to metrology law. kW builds the system; kWh pays for it.