Devices contain labels with their corresponding average energy requirements in order to function properly. For example, a set of light bulbs can provide similar brightness levels but have different energy consumption requirements. An incandescent light bulb may consume up to 60-watt of power whereas a LED bulb only 8.5 watts. If our average daily light bulb use is 4 hours per day during 350 days per year, our total energy consumed would be 84,000 watts per year or 84 kWh per annum. Assuming an average rate of €0.25 kWh for household consumers (based on Eurostat), our total cost for using the incandescent light bulb would be €21. If we had used the LED bulb, it would only have cost €2.95!
Whilst lightbulbs energy’s usage is quite stable, energy consumption for other appliances can be highly variable. For example, refrigerators’ energy consumption varies depending on whether the compressor is being activated to cool down the interior of the fridge or whether it is sitting standby. Likewise, coffee machines are typically high energy consumption appliances. As soon as you start the process of making coffee, it pulls a lot of energy to heat up the water and once it is done, its electrical current diminishes substantially to a level known as the “background power” level.
Governments around the world are requiring manufacturers to provide a more transparent disclosure of their products’ energy efficiency. In the EU, power appliances’ ‘energy labels’ assign products a category, A being the most efficient and G the least amongst its category. These labels also provide general information on how many kWh per year are consumed and other non-energy parameters such as noise, emissions, water consumption etc.
Energystar website created by the U.S. government provides energy consumption figures for a wide range of power appliance devices such as TVs, refrigerators, washers, dryers, heat pumps etc. You are able search specific brands and products and compare their respective kWh yearly consumption profiles with each other.
Determining energy usage from an electric bill
Understanding your energy bill is crucial if you want to know how many solar panels you need to cover your energy consumption requirements.
Firstly, your bill might also include other services such as gas and water. It will depend on the utilities company that you hired and the country and region where you are located.
As you can see in image 1, your electricity bill will typically contain your customer account number, statement date and your payment due date. If you have any outstanding balance from previous periods, you will also be able to see it.
In some cases, you can also see your billing history broken down on a monthly level but also your average daily energy consumption on different years (given that you have been with the same company in the same place during that time). In some countries, electricity consumption is divided by tiers. For example, in Mexico City, as long as you consume under a specific threshold you have a government subsidy available per kWh which lowers your overall electricity cost. Once you consume more than a certain threshold, you will pay the full cost. This sort of government policies attempt to instill energy conservation behaviors across countries and cities.
If you look at that electric charges breakdown from image 2, you will see that there is a line called “Conservation Incentive” of $9.50. This is a type of discount given to a household that consumed less than a certain threshold and therefore are eligible for such program.
Then you have the transmission and distribution (T&D) costs which include all the network investment that utility companies must make to transfer the electricity from source generators to your home.
Other costs shown above include things such as:
- Nuclear decommissioning: these are the costs incurred when nuclear plants in the country are being shut down, cleaned and replaced by other type of power plants aligned with the government energy goals and initiatives.
- DWR Bond Charge: in this particular example, these are the costs incurred for financing specific energy-purchases during times of crisis or high costs where government borrowing takes place.
- Energy Cost Recovery Amount: These are costs charged to customers to cover unexpected events or power disruptions.
- Other taxes
Every city and country and even utility company has a different way of presenting the costs. Most of them follow government regulations and they are obliged to breakdown the costs in a simple manner for customers to understand.
When assessing your energy consumption, it is typically recommended to take monthly kWh values given to you in the electricity bill and compute seasonal or yearly averages. You can then compare those results against previous years and see how much electricity you will require your solar panels to cover for your average monthly electricity need.