why is kwh the unit for consumption of electricity?

Answer 1

A kilowatt-hour (kWh) is a unit of energy, just like the Joule, calorie, or Calorie.

The watt is a unit of power (energy / time). Hours are a unit of time.
If you multiply power by time, you get energy. Thus, at a constant power of 1 kW, operating for 1 hour, an appliance will consume 1 kWh of energy.
It is this simply conversion rate which makes the unit desirable to use since most major appliances operate in the range of a few hundred watts. For example, Things like Microwaves have a power rating which is roughly on the order of 1000 Watts (1 kW). A 100 Watt light bulb consumes…you guessed it….100 Joules of Energy per second (100 Watts). If you leave this light bulb on for 1 hour, it will consume 0.1 kWh of energy.

Using the unit of kWh is sometimes easier because of the size of the unit compared to other units (like the SI unit of energy, the Joule).
1 kW = 1000 Joules per second. 1 hour = 60 minutes = 60 * 60 seconds.
1 kWh = 1000 J/s * 3600 seconds = 3600000 Joules
Look how big that energy value gets, and this is only 1 kWh. It is just more convenient to use the bigger unit for measuring out electrical energy consumption than having to carry around all of those zeros or use scientific notation.

Answer 2

Because it is easier to understand than the official unit of energy, the Joule, or the old official unit, the Calorie. It's also a bigger unit, so the numbers are more manageable.

A single bar heater uses about a kilowatt of power, so in an hour it uses one unit (1 kWh) of electricity. This is easier than saying that it uses 3,600,000 Joules.

Answer 3

Kilowatts (kw) is power and power over time (h) is energy, kwh. The watt is a common unit and kilowatt (1000 watts) per hour provide a convenient number.