Update: I am actually searching for really simple, intuitive ways to explain it. I have a background in engineering, but am struggling to explain why we “pay for kwh”, and not kw (on our electricity bill) to someone who doesn’t. I have tried in many ways but maybe I’m not giving the right examples or making the right comparisons. I am really searchig for a way to ELI5.
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Look at the units to determine the difference.
A kilowatt is Joules per second. So a kilowatt measures the rate of energy used. This is similar to how a car gets miles per gallon.
Then there’s the kilowatt hour. So an hour is the same kind of unit as the second, time, so it’s the same thing. So a kilowatt hour is really just Joules per second, times however many seconds – (J/s)*s. The time units cancel out, and we’re left with Joules. This is a measurement of energy used.
Your car gets say 10 miles per gallon. But when you go to the gas station, you buy gas based on your miles per gallon and how many gallons you have used.
Your house uses say 10 kw of energy (every second, 10000 Joules of energy is used). When you pay the electric company, you pay for the 10 kw times the number of hours the electricity has been on.
Maybe a better explanation is speed. I go running at 10 miles per hour. If I want to know how far I have ran, I need to know how long I have been running. I am not a good runner, so I can only run for a few seconds. So we have miles per hour times seconds – (M/h)*s. The time units cancel out so we’re left with just miles (more like feet, but feet and miles are the same thing – distance). This is the same thing as kwh.
The important distinction between kWh and kW is that a kWh reflects the total amount of electricity used, whereas a kW reflects the rate of electricity usage
Here is how I would explain it:
A kW is a measurement of how much electricity you are using RIGHT NOW. A kWh is essentially a measurement of how much electricity you used in total. So if you use 1 kW for an hour straight, you’ll be charged for 1 kWh of electricity.
kW are a measure of power, energy consumed over time. A Watt is a Joule/second. The rate you consume energy
A kWh is a measure of energy. It’s a kW * h or (kJ/second) * hour, or 1kWh = 3600 kJ
A 100W bulb running for 10h consumes 1 kWh
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