The electric vehicle revolution is just around the corner, powered by solar panels. Battery efficiency continues to increase and costs decrease, and people are becoming more environmentally conscious.
For many people who haven't taken the plunge and invested in solar, one of the burning questions we often get is how many solar panels they will need to charge an electric car. People want to strike a balance between powering their homes efficiently, filling up their batteries, and making sure their electric car is charged enough to get them around town.
Fortunately, the vast majority of installations across Australia can charge a car with their solar panels and have more than enough left to keep household appliances running. We used some industry averages and made some assumptions to help you determine the number of panels you will need to charge your EV.
Electric cars and kilowatt hour consumption
One of the most important factors in the number of solar panels you need to charge your electric car is the amount of electricity you use per km. We can use the range of the most popular vehicles per kilowatt hour to determine the amount of power they need and the type of distance we can expect. Below are some of the best electric cars on the market and their range per kilowatt hour:
Tesla Model 3: 7 kilometers
Chevrolet Bolt: 6.4 kilometers
Mitsubishi i-MiEV: 6.3 kilometers
2016 Nissan Leaf: 5.7 kilometers
Tesla S sports car: 5.3 kilometers
Distances will vary as electric vehicles do not allow the batteries to run out completely. The actual numbers are therefore slightly higher. It also depends on your driving style. If you put a lot of pressure on the accelerator and then hit the brakes hard, you will get fewer miles than someone who drives more carefully.
We'll work with the 7km number for the remainder of the article to keep the calculations consistent.
Electric vehicle charging and removal
The charging process is not 100% efficient, so some power is lost when you have your car plugged in. These losses occur when converting the alternating current generated by your home to the direct current used by the batteries and by the batteries themselves. So you have to generate a little more electricity than required to account for these losses.
The efficiency varies depending on the model of your electric vehicle and the charging method you use. Expect worse charging results from standard household sockets than the standard household chargers, which are additional costs to install. As a rule of thumb, however, you should get around 90%.
So if you take the battery at 7 kilometers per kilowatt hour and drive carefully, you will likely get 6.3 kilometers per kilowatt hour of charge. To get round numbers, we proceed conservatively in our estimate and assume that you will achieve an average of 5 kilometers per kilowatt hour.
The average Australian drives 38 kilometers a day. So if you use the range of 5 kilometers from above for every kilowatt hour of power, you only need just under 8 kilowatt hours of energy per day.
Of course, the actual distances you travel each day will vary greatly depending on where you live. So you need to calculate your daily average to get accurate results.
Various electric vehicle charging methods and power outputs
The easiest way to charge an electric car with your solar panels is to use a standard electrical outlet during the day when excess energy is being generated. Using a regular electrical outlet is known as level 1 charging and is usually incredibly slow, charging at a rate of 2.3 kilowatts.
Level 2 charging is significantly faster, with an output of 3 to 7 kilowatts, but requires installing a special charger in your garage or outdoors. Depending on the manufacturer of your vehicle, you may need to purchase a level 2 charger to benefit from the warranty.
Level 3 charging is done using special public chargers and is fast. You can charge vehicles up to 32 times faster than a level 2 charging port, and fully charge some cars in 30 minutes. However, these are usually funded by the government or the private sector and are not intended for domestic use.
Depending on whether you are using level 1 or level 2 chargers, the power required by your solar panels will vary. Slower loading reduces the chance that you will even need to use the network, but it is slow. If you use a faster charger, it will refill faster. During peak periods of household electricity consumption, your solar system is unlikely to meet the increased demand, and utility grid help may be required.
How many solar panels do you need to charge an electric car?
If you drive the Australian average of 38 kilometers per day and get 5 kilometers per kilowatt hour of electricity from your battery, you need 7.6 kilowatt hours of electricity per day. The typical Australian solar system gets roughly four kWh per day for every kW of solar modules, which means that a 5 kW solar system will provide 20 kWh of electricity per day.
So you only need a 2 kW solar system to provide enough energy to drive your electric vehicle. How many solar panels do you need to charge your electric car? If you've installed a newer system with 370W panels, you only need 6 panels. If you have older 250W panels, eight panels will meet your vehicle's energy needs. Realistically, almost all of our installations are far larger, and the extra capacity means there is more than enough solar power to run both home appliances, charge an electric vehicle, and charge a battery for the house, so you can use excess solar power in the power Night. A 10 kW solar array is a popular size for households looking to do all of this.
Charge your electric vehicle with solar panels
So in summary, there are several variables to consider when figuring out how many panels you will need to power your electric car. The vehicle model, the distance traveled, your driving style and the ambient conditions all affect the power consumption of the vehicle.
The average Australian household can sometimes power their vehicle with just 2 kilowatts of energy or around 6-8 panels, depending on the rated power of the panel. As solar costs continue to decrease and battery technology improves so quickly, it is now possible to build an "electric lifestyle" around your electric vehicle in which you can use your solar system to reduce your costs even further.
Find out more
Solaray is Australia's solar and storage expert. We were voted Australia's best solar installer in 2020 by Enphase and LG Solar. Request a call back from the team today for more information on how we can help you get the most out of solar energy, battery storage, and an electric vehicle:
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