kW vs kWh: how knowing the difference can help slash your energy bill

The difference between kW and kWh can be complicated and not something that is commonly known by the average household in Australia. In fact, many energy experts still wrestle with the differences between the two.

But understanding what these terms mean will give you a huge insight into properly reading your electricity bills and understanding your energy consumption overall.

This will give you the tools you need to better manage your consumption in the future, and slash hundreds of dollars of your annual bills in the process.

So, what is the difference between kW and kWh?

Fundamentally, the distinction between kW and kWh is fairly simple – kilowatt (kW) is a measure of power while kilowatt-hour (kWh) is the measure of energy.

But this is also where things can get complicated and confusing, after all, aren’t power and energy the same thing?

There are very important differences, so before we delve too deeply into kW versus kWh, let’s understand what power and energy are and why they are different from each other.

Energy: The simplest way to describe energy is the capacity to do work. We use energy every single day for simple tasks like walking to the train station, cleaning up the house and mowing the lawn. We also use this energy to fuel our cars, to heat and cool our homes and offices and make our appliances work. This is measured in many ways, including the kilowatt-hour.

Power: Energy needs to be transferred at different rates depending on how much force is required to make something move. Power is the rate at which energy is transferred, which can be a little to operate a simple item like a blender, or a lot to transfer enough energy to power a motor vehicle. This is usually measured in watts, with a kW a measure of 1000 watts.

So, appliances will have a kW rating which will tell you how much energy they will need to run. Lightbulbs are an easy example as they have the wattage clearly written on the box.

If you purchase a 100-watt lightbulb, it is going to take 10 hours for it to consume 1 kWh of energy.

This is important to know, as electricity providers and resellers are going to charge you per kWh and different states and different plans all have different kWh rates.

Understanding which appliances require more energy (kilowatt-hours) to run

By learning the power requirements of your appliances in watts and kW, you can understand how much they are going to be a drain on your electricity bill and adjust your usage accordingly.

These figures are meant as a guide only (as different appliances from different manufacturers vary), but this is the average power consumption of basic household appliances:

  • Blender: 500 watts
  • Toaster: 850 watts
  • Microwave: 1 kW
  • Vacuum: 1 kW
  • Dishwasher: 1.5 kW
  • Hairdryer: 1.5 kW
  • Clothes dryer: 3 kW
  • Wall air conditioner: 3.25 kW
  • Central air conditioner: 3.8 kW
  • Electric water heater: 4.5 kW
  • Electric water heater (tankless): 18 kW

There are other appliances, like fridges and freezers, that will have alternating wattage requirements as they will only operate at maximum capacity at certain points of the day. This is the same with computers and televisions when they go into “sleep mode”. While they will require less kWh to run, they will still be taking up a considerable consumption rate.

This list shows that small appliances like the average vacuum and hairdryer require a lot of power to operate. It also shows that luxuries like tankless water heating options can be very expensive to run, which give you some tips on how to save on your electricity bill.

Understanding your electricity bill

Many of us will only look at the amount we have to pay, sometimes glancing at other metrics like the average electricity usage per day etc.

But there are plenty of graphs and measurements on your bill which can help you get a strong handle on your energy consumption and work out ways to reduce it.

These will also show your kWh usage over different times, including peak and off-peak windows. If you are using a lot of power in peak periods, you can reduce your usage in these times and also explore different tariffs and rates with your electricity provider.

Ultimately, you can also compare your kWh usage to other households in your area, so you can tell if you are using more power than your neighbours and work out strategies to useless.

Now that you know what the kWh metric is, you can use this to your advantage as well. Shop around, as different electricity providers and resellers will charge different rates during different periods and this will all be listed in kWh. Compare them all – or use a comparison website – and get the best possible deal for your household.

How solar panels work in terms of kWh and kW.

Many people know that installing solar panels will reduce their energy bills, but don’t understand exactly why.

Solar systems are usually sold with a rating. For example, you might be looking to invest in a 5kW solar array for your home. That means 5kW is the maximum output this system is capable of at any given point in time.

This will fluctuate depending on sunlight and other factors, so you cannot expect a constant flow of 5kW from your system.

What you want to look at is the kWh that your system is producing for your home. If a solar system is consistently producing 1kW of power over the course of an hour, you will get 1kWh of energy for your home.

This is where you can refer to the previous list (and the ratings on your appliances themselves).

If you are getting 1kWh every hour of the day, that means you are getting enough power to run your microwave 24 hours a day (not that you would do that).

So when looking at a solar system, always focus on the kWh it is producing rather than the kW rating it comes with so that you can get a complete picture of how the system is going to benefit you.