What is the difference bw kwh and kw why we need to consider kwh reading than kw reading for power consumtions?

Answer 1

KW, or kilowatts, is a measure of instantaneous power. KWH, or kilowatt-hours is the power used over time.

Suppose I have a light bulb. It is a 100 watt bulb. You are going to build a small power station to supply me with power. Now, a 100 watt bulb is 0.1 KW, since 1 KW is the same as 1000 watts. Say you buy a little gasoline generator and some fuel to run it. Lets say you decide to charge me one dollar per KW.

I turn on the light bulb for one minute. You measure 0.1 KW on my meter, so you charge me 10 cents ( $1.00 per KW * 0.1 KW = $0.10). Well, ten cents is not too bad, after all, you only had to supply power (and buy fuel), for one minute.

I turn on the light bulb for a week. You again measure 0.1 KW on my meter, so again, you charge me 10 cents. Do you see a problem with this? KW is simply how much power it takes to light the bulb. It has nothing to do with how long you run it. You will quickly go broke supplying me with power.

So, we need to have something that accounts for the time power is supplied. That's what kilowatt-hours do. If I run my 100 watt bulb for one hour, that's 0.1 KWH. If I run it for 5 hours, that's 0.5 KWH, 100 hours is 10 KWH, and so forth.

Now suppose you again agree to supply me with power. This time though, you decide to charge me one dollar per KWH.

I turn on the bulb for one hour. The KWH is 0.1 KW * 1 Hour = 0.1KWH. You charge me $0.10.

I turn on the bulb for a whole day. The KWH is 0.1 KW * 24 Hours = 2.4 KWH. You charge me $2.40.

Ah, much better. Now, the longer you have to run the generator and supply me with power, the more money you will get. If I change my bulb to a 200 watt, you will need more fuel to run your generator, but you will get more money. If I run the bulb longer, you will also need more fuel, but you will also get more money.

That's the main reason power companies primarily bill for KWH used. For commercial customers, it gets a little more complex, but that's another question!

Answer 2

kWh (kilowatt-hour) measures energy consumption over time, while kW (kilowatt) measures power at a specific moment. We use kWh readings for power consumption because it accounts for both the power used and the duration it was used for, giving a more accurate representation of overall energy usage. kWh readings also factor in how long the energy was consumed, which is essential for billing and energy efficiency assessments.