What is the Difference Between kWh and kW?
If you have been interested in going solar, kW and kWh has most likely come up a few times. If you are confused by this, don’t worry. It’s easy to get kilowatt (kW) and kilowatt-hours (kWh) mixed up when talking about energy consumption. The main difference between kWh and kW is in what they measure. To put it simply, a kilowatt is a measure of power and a kilowatt-hour is a measure of energy; power is the rate at which something uses energy, and energy is the capacity to do work.
For example; your energy bill, the kWh measures the amount of energy that an appliance or device needs to run for one hour. To clear any confusion let’s break the definitions down a little further:
The Kilowatt
A kilowatt is simply a measure of how much power an electric appliance consumes—it’s 1,000 watts to be exact. You can quickly convert watts (W) to kilowatts (kW) by diving your wattage by 1,000:
1,000W / 1,000 = 1 kW.
The Kilowatt-Hour
A kilowatt-hour measures the energy an appliance uses in kilowatts per hour. For example, if you clean your floors with a 1,000-watt vacuum cleaner for one hour, you consume 1 kWh of energy.
Your kilowatt-hour consumption factors in how many watts your appliances use and how often you use them. When you see kWh on your monthly energy bill, it’s a measurement of your electric appliances’ wattage and the amount of time you use them.
The difference between kWh and kW, and what you see on your bill, is that:
- kW reflects the rate of electricity you use
- kWh indicates the amount of electricity you use.
Here is an example of kW vs kWh in the context of low- and high-power appliances to give you a better idea of how these two units affect each other:
Lower watts: If you are using a 100-watt device, such as a plasma TV, you would have to watch your favorite shows for 10 hours before reaching 1 kWh.
Higher watts: If you are running a 2,000-watt appliance, such as a clothes dryer, you only need to power it for 30 minutes to reach 1 kWh.
The power you use on a daily basis can quickly add up to 1 kWh if you are frequently using high-wattage appliances in your home. Keep this in mind, as energy companies typically charge for power on a per-kWh basis.
CALCULATE KWH VS. KW
Let’s use a 1500W dishwasher you use for two hours per day as an example for calculating kW and kWh on a monthly basis:
Divide the wattage by 1,000 to calculate kW: 1500 watts 1,000 = 1.5 kW
Multiply the kilowatts by the hours of daily use: 1.5 kW X 2 hours = 3 kWh per day
Find the total energy usage for a month (30 days): 3 kWh X 30 days = 90 kWh per month
Now that we know the monthly kWh for this device, let’s estimate the energy costs. Multiply the kWh by your electricity provider’s monthly electricity rates. For the sake of this example, we’ll say it’s $.07 per kWh:
90 kWh X $.07 per kWh = $6.30 per month
Make a list of appliances that you frequently use and do the same calculations. You can then start to balance your usage by examining which appliances require the most power (kW) and energy (kWh).
HOW DO COMPANIES MEASURE MY USAGE?
Utility companies measure your kWh with digital meters right outside of your home where the power line goes into the property. While traditional meters require a utility service to come to your home, newer digital meters have an electronic display that uses a high-frequency signal to send data to the utility companies.
Monitor Your Electricity kWh
Now that you have a better understanding of kW versus kWh, and the different uses of electricity, you can take a closer look at your bill and begin to analyze your energy consumption. For a more detailed understanding, consider investing in a home energy monitor. Many monitors available today are wireless and display your home’s energy consumption in an app. Depending on which monitor you choose, you may even be able to turn appliances on and off when you’re away from home using the app.