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kW, kWh And Kilowatt/hour: What Do They Mean?

Feed-in tariffs in Victoria could be as high as 29c per kWh under a new rate.

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

But understanding these terms will give you tremendous insight into correctly reading your electricity bills and overall energy consumption.

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

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So, what is the difference between kW and kWh?

kW vs kWh: Understanding the terminology

The distinction between kW and kWh is relatively simple – kilowatt (kW) is a measure of power, while kilowatt-hour or kilowatt/hour (kWh) is a measure of energy. So, if you use a 1000-watt hair dryer for one hour, you will have used one kilowatt-hour (kWh) 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 significant differences, so before we delve too deeply into kW versus kWh, let’s understand what power and energy are and why they differ.

Energy: The simplest way to describe energy is the capacity to do work. We use energy daily for simple tasks like walking to the train station, cleaning the house, and mowing the lawn. We also use energy to fuel our cars and heat our homes and offices. It 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 move something. 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. It is usually measured in watts, with a kW of 1000 watts.

  • K represents kilo. it denotes “1,000.”
  • A Watt, a power unit, is denoted by the sign W.
  • Hour, the symbol for h, is a unit of time.

So, what is the difference between kW and kWh?

Kilowatts (kW) refer to the rate at which energy is used or generated at a particular moment. It is a power measurement unit, with one kilowatt equal to 1,000 watts. Power is the energy required to perform a particular task in a unit of time. For example, a 1 kW appliance will consume one kilowatt of power per hour when running.

On the other hand, kilowatt-hours (kWh) measure the total amount of energy consumed over a period of time. It is a unit of energy measurement, with one kilowatt-hour equal to 1,000 watt-hours. Energy is the ability to do work measured in joules or watt-hours. For example, a 1 kW appliance running for one hour will consume one kilowatt-hour of energy.

Regarding billing, energy retailers in Australia use kWh to measure the amount of electricity consumed by a customer. The price charged per kilowatt-hour varies depending on the retailer and the plan chosen by the customer.

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 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.

It is essential, as electricity providers and resellers will charge you per kWh, and different states and plans have different kWh rates.



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How to calculate kW and kWh

Calculating kW and kWh is relatively simple, and it’s a good idea to know how to do so to understand your energy usage better.

Kilowatt

To calculate kW, you need to know the amount of power used and the time it’s used for. You can use the following formula:

kW = Power (Watts) / Time (hours)

For example, if you have a 2000-watt air conditioner that’s been running for four hours, the calculation would be as follows:

kW = 2000 watts / 4 hours = 500 kW

Kilowatt-hour

To calculate kWh, you need to know the amount of energy used and the time it was used for. You can use the following formula:

kWh = Power (Watts) x Time (hours) / 1000

For example, if you have a 1000-watt hair dryer that’s been used for 30 minutes, the calculation would be as follows:

kWh = (1000 watts x 0.5 hours) / 1000 = 0.5 kWh

Why is understanding kW and kWh important?

Understanding kW and kWH is important because it helps you better understand your energy usage and associated costs. Energy companies charge customers based on the energy used, measured in kWh. Therefore, knowing how much energy you’re using can help you manage your energy consumption and reduce your energy bills.

Understanding kW can help you determine the capacity of your electrical appliances and equipment. This can be important when purchasing new equipment or ensuring your electrical circuits can handle the load.

The importance of kW and kWh in energy efficiency

Energy efficiency is a critical aspect of sustainable living. It is essential to understand the various terms that relate to it, including kilowatt (kW) and kilowatt-hour (kWh). These terms are crucial in measuring and monitoring energy consumption and understanding how to conserve it.

In Australia, energy consumption is a significant concern, with residential and commercial buildings accounting for 40% of the country’s total energy consumption. This is why promoting energy efficiency in these sectors is crucial, and understanding kW and kWh is a crucial part of this process.

Understanding kW can help individuals and businesses choose energy-efficient devices that consume less power and reduce their energy bills, such as air conditioners, refrigerators, and other appliances.

On the other hand, kWh is the product of the power consumed in kW and the duration for which it is used. For example, kWh is crucial in monitoring energy consumption and identifying opportunities for energy savings.

One of the ways to conserve energy is by choosing energy-efficient appliances and devices that consume less power. The Australian Energy Rating Label is a useful tool that provides consumers with information on the energy efficiency of various appliances. The label rates appliances on a scale of 1 to 10, with 10 being the most energy-efficient. Consumers can reduce their energy bills by choosing appliances with higher ratings and contributing to the country’s energy conservation efforts.

Another way to conserve energy is by reducing energy waste. Simple practices such as turning off lights and appliances when not in use, using natural light instead of artificial light, and adequately insulating buildings can significantly reduce energy waste and consumption.

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 will impact 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 essential 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

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

Other appliances, like fridges and freezers, will have alternating wattage requirements as they only operate at maximum capacity at specific day points. It is the same with computers and televisions when they go into “sleep mode”. While they will require less kWh to run, they will still take 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 indicates that luxuries like tankless water heating options can be costly, giving tips on saving 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 use much power in peak periods, you can reduce your usage and 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 be useless.

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

How knowing the difference can help slash your energy bill?

When comparing prices, it’s crucial to consider service fees, discounts, and the cost of electricity per kWh used.

Finding the most excellent electricity deal requires energy literacy. Now that you are familiar with kWhs, you should routinely review your bills to see how your electricity usage compares and whether there are any savings to be had by cutting back on your use, locating a better deal, or doing both.


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How do solar panels work in terms of kWh and kW?

Many people know installing solar panels will reduce their energy bills but sometimes don’t understand 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 can produce at any given time.

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

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

You can refer to the previous list (and the ratings on your appliances themselves).

If you are getting 1kWh every hour of the day, you are getting enough power to run your microwave 24 hours a day (not that you would do that, nor do solar panels work at night!).

So when looking at a solar system, always focus on the kWh it produces rather than its kW rating to get a complete picture of how the system will benefit you.

Become an energy efficiency saving expert

Can I cut back on my electricity usage? You can calculate what a single kWh is worth to see the energy used in your home.

Greater energy efficiency means that solar power will supply more of your electrical demands, lowering your power costs even further and maximising the benefits of feed-in tariffs, even if you are only partially powering your home with solar panels.

Switching to a better plan?

You may already have an energy plan but want to shop for a better deal.

Energy Matters Energy Health Check” is a cutting-edge energy comparator tool that allows you to compare your area’s most competitive retail offers. We collect the data from our wide range of trusted retailers, allowing you to decide about changing your plan.

If your goal is to minimise the cost of your gas and electricity bills, switch to a better plan now!

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