kW vs kWh

kW Vs kWh

One of the easiest and most common mistakes to make when talking about electricity is using the terms kW and kWh interchangeably.

The following article will end the confusion by providing clear definitions and examples for kW and kWh.

What They Stand For

  • k stands for kilo
  • W stands for watt
  • h stands for hour


Kilowatt (kW) is a measure of power. Notice that the k is lowercase and the W is uppercase. Peak power is the size of the solar system, for example a 6.6kW system can produce a peak of 6.6kW around midday when the sun is the strongest.


Kilowatt-hour (kWh) is a measure of energy. Notice that the h is lowercase. If solar panels output a continuous 6kW for a whole hour, the amount of energy produced is 6kWh.

Why the Difference is Important

If looking to buy a solar system, you may calculate that your daily energy usage is 10kWh.

If you mistake kWh for kW, you may say, “I need 10kW of solar to power my home daily!”

So, you purchase a 10kW solar system for $10,000.00 and you produce 40kWh per day.

Really, you needed 2.5kW of solar for your needs.

kW and kWh and Batteries

kWh refers to how much energy the battery can store. For example, a Tesla Powerwall II battery stores 13.5kWh.

kW refers to how quickly the battery can charge or discharge. For example, the Tesla Powerwall’s power is 5kW. The battery can charge in just under 2 hours. The battery can discharge at a rate of 5kW per hour.


Q: What does kW stand for?

A: kW stands for kilowatt, which is a unit of power. Power is the rate at which energy is consumed or produced.

Q: What does kWh stand for?

A: kWh stands for kilowatt-hour, which is a unit of energy. Energy is the total amount of power consumed or produced over a period of time.

Q: How are kW and kWh related?

A: kW and kWh are related by time. kW measures the instantaneous power consumption or production at a given moment, while kWh measures the total energy consumed or produced over a period of time.

Q: When should I use kW and when should I use kWh?

A: You should use kW when referring to the power rating of a device or system, such as the power output of a generator or the power consumption of an appliance. You should use kWh when referring to the total energy consumed or produced over a period of time, such as the electricity usage on your utility bill.

Q: How can I convert between kW and kWh?

A: To convert from kW to kWh, you need to multiply the power in kW by the time in hours. For example, if you have a device that consumes 2 kW of power for 5 hours, it would consume 10 kWh of energy (2 kW x 5 hours = 10 kWh).

Q: Are there any other units of measurement related to energy consumption?

A: Yes, there are other units such as megawatts (MW) and megawatt-hours (MWh), which are larger units of power and energy, respectively. These units are commonly used in the context of large-scale power generation and distribution.

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