Watt

basic SI (international system) measure of electricity (1 joule/second)

joule

basic SI unit of work or energy

kW

1000 Watts

kWh

kilowatt hours (kilowatts of electricity consumed over 1 hour)

kWh/y

kilowatt hours per year

MW

megawatts: 1 million Watts

GW

gigawatts: 10⁹ Watts (one thousand million Watts)

terawatts

10¹² Watts (one million million Watts)

petajoules

10¹⁵ joules (one thousand million million joules)