Watts

Used to measure the amount of work able to be done with a given amount of electricity. Amps x Volts = Watts.

kW (kilowatt)

Watts divided by 1,000 (1kW = 1,000 watts; 4kW = 4,000 watts, 0.5 kW = 500 watts).

Volts

Are used to measure the “force” of electricity flowing. One common example is to compare electrical volts with water pressure, or pounds per square inch (PSI). Volts do not measure how much electricity is flowing, but rather the force or pressure at which it is flowing.  Watts / Amps = Volts.

Amps

Used to measure the quantity of electricity passing a certain point in a given period of time.    This is independent of force or pressure (volts) and when compared to water, is comparable to gallons per minute (GPM). Watts / Volts = Amps.

Watt-hour

Used to measure how many watts have been consumed or produced over a given period of time. 1 watt-hour = 1 watt for 1 hour; 10 watt-hours = 10 watts for 1 hour (also 5 watts for 2 hours or 20 watts for 0.5 hours).

kWh (kilowatt hour)

Watt-hours divided by 1,000 (1kWh = 1,000 Watt-hours; 3kWh = 3,000 Watt-hours). This is the typical measurement used by utility companies on your power bill.

AH (amp-hour)

The number of amps flowing over a period of time (1 amp flowing for 1 hour = 1 AH; 4 amps flowing for 1 hour = 4 AH; 4 amps flowing for 2 hours = 8 AH; 4 amps flowing for 0.5 hours = 2 AH). Often used for batteries.

Series

Multiple batteries wired together in such a way that voltage increases, but the amp-hour capacity does not.

Parallel

Multiple batteries wired together in such a way that voltage stays the same, but the amp-hour capacity increases.