Difference between Kilowatt and Kilowatt-hour

Kilowatt (kW) is a unit of power measurement. In other words, the kW is, by definition, the amount of energy absorbed in unit time. One kW, equal to 1,000 Watts, identifies the unit of electrical power (W = J / s) and represents the amount of energy (Joule) over time (seconds). 

Kilowatt-hour (kWh) is the unit of measurement of electricity. In fact, the Kilowatt-hour it's composed of the terms Kilowatt and hour and indicates the Energy supplied in an hour of time with the power of one Kilowatt.

The two units of measurement are different. The kW measures power, while the kWh is the unit of electricity consumption measurement. A simple example:

If you have an appliance in your home that has a power of 2 kW, it means that it absorbs 2kW per unit of time (Snapshot). So if you use it for one h, it will consume: 2 kW * 1h = 2 kWh, in case it was 2 hours, 2KW *2h = 4 kWh

 Power and Energy

• The electrical power (P) that passes through a circuit section is given by the product of the voltage (V) and current (I) present in the section considered:

P = V × I (Unit of measurement of power is Watt, abbreviated: W)

• Electricity energy (W) is the product of power (P) times time (t). The unit of measurement of energy is the kilowatt-hour, which is abbreviated to kWh

W = P × t (kWh)

Clarifications

I would like to clarify Electricity, Power, and Energy. 

The Ampere (A) is the measure of the Current, while the Power is produced by the Current and is measured in Watts (W), and the formula that binds them is: Power (P) = Current (A) x Voltage (V). So, if the Current remains unchanged and the Voltage varies, for example, 15 Amps and 20 Volts, they produce 300 Watts of Power, while if the current remains the same, but the Voltage varies, Example 48 Volts:

the Power will be 720 Watts, the difference is too big. So the Current (A) is used to size the cables, the regulators, and partly also the batteries, while the Power (W) I need to understand how much "work" the Current produces with the Voltage you choose.

All this reasoning is acceptable when it happens instantaneously, but it is clear that a 50 Watt light bulb kept on for an hour consumes less than the same light bulb kept on for 2 hours, even if the Power is always 50 Watts, so I have to find a simple method for calculation, by comparing consumption or production as if it had occurred in a single hour. This ratio is the Watt-hour (Wh) which is the Energy and is equal to the Power for the time (W = P x t) for which the 50 Watt light bulb kept on for one hour will consume 50 Wh of Energy, and the one kept on 2 hours will consume 100 Wh.

Summary

• A = current flowing at this moment is like the flow of water in a tube that supplies the vessel.
• Wh = Wh = total energy used, produced or accumulated. It is like a bank account.
• W = instantaneous power produced or consumed. It is how much work we can do at the same time.

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