What Is a kW vs. kVA?

kW (kilowatts) measures real, usable power — the number generator brands advertise and the figure used for sizing your system. kVA (kilovolt-amperes) measures apparent power, a related but slightly larger number due to a factor called power factor. For most residential standby generators the two numbers are close enough that kW is the only figure you need to pay attention to when comparing units or sizing a system.