The watt (W) is the derived unit of power in the SI system of units. 1 watt is defined as the consumption of energy at the rate of 1 joule per second. It is named after the Scottish engineer James Watt.
One ampere of current flowing at a potential of one volt produces one watt of electric power. One watt equals 1/746 horsepower. One megawatt = 1 million watts, and is a standard measure of electric power plant generating capacity. One gigawatt (GW) = 1 billion watts.