Kilowatt-hour (kWh) and Kilowatt (kW)?

The kW and the kWh are two concepts that intervene in your bill and make up the price you pay for energy. The kW determines the contracted power and the fixed term that you pay for the electricity, while the kWh will be the indicator of the energy consumed from electricity or gas and will determine the price you pay for your consumption.

Kilowatt-hour (kWh) and Kilowatt (kW)?

This is a type of confusion that occurs constantly. We tend to talk about  kilowatt-hours  and  kilowatts  indifferently, when both units are very different from each other. Let’s see what they consist of and what each of them measures.

To do this, we are going to give an example:

Imagine that you are thinking of  saving a little on the electrical consumption of your house  and for this you have decided to change all the bulbs in your home for some LED bulbs. Those bulbs, as you well know, have their power indicated, and let’s say you are going to buy about 20 LED bulbs with 50W of power each.

Well, those 50W express the power in Watts (W) of the bulb. If you connect all 20 bulbs at the same time, you would have:

20 x 50W = 1,000 Watts (W)

First common question: kW or W?

The first thing you should know is that a kilowatt or a watt is a measure of  electrical power . That is, if you have a 50W bulb, those 50 watts is what the bulb will consume.

Here arises the first of the usual doubts:  do you say kilowatts or watts? .

It’s simple, as we mentioned in our article ( volts, watts, amps ), a kW is 1,000W. Simply, for short, when we have more than 1,000 Watts (W), we indicate it as 1 kilowatt (kW), also, in English, kilowatt.

In case you need more references:

1 kilowatt (kW) = 1,000W
1 megawatt (MW) = 1,000kW = 1,000,000W
1 gigawatt (GW) = 1,000MW = 1,000,000kW = 1,000,000,000W

Kilowatt-hour (kWh)

What does kilowatt-hour (kWh) mean? : is a measure of electrical energy. So there you have the first difference from kW to kWh.

Continuing with the example of the 50W bulb, if we leave it running for 1 hour, it will have consumed an energy of 50 Watt-hours (Wh). But now imagine that that light bulb is on every day for an hour. Then you could know the monthly energy consumption of that light bulb, like this:

1 hour of operation for 30 days = 30 hours in which the bulb is on
30h x 50W = 1,500 Wh-month, or what is the same 1.5kWh-month

Summarizing:

That is, following with our friend the light bulb:

The power of the bulb is 50W and it is measured in watts or kilowatts, but the energy that it will need to be able to work those 30 hours a month, would be 1.5kWh and it is measured in kilowatt-hours.

If you put the 20 bulbs to work at the same time, for one hour, the energy consumed will be 20 x 50W x 1 hour = 1,000 Watt-hours (Wh), or what is the same, 1 Kilowatt-hour (kWh).

Because it is important?

Knowing the meaning of the kilowatt-hour (kW) is essential to be able to analyze the  consumption of household appliances in your home  and to be able to rethink ways to  save energy . In addition to this, you can always analyze your contract and electricity rate to check if everything is correctly billed or if there is a way to improve it. In the end this directly affects your pocket and the economy of your home, the less energy you consume (kWh), the less you will have to pay at the end of the month.