How Many Solar Panels To Charge An Electric Car? Full Answer Here.
Updated: Mar 9, 2019
Lots of us are switching to electric vehicles (EVs) to save money and protect the environment. If you own an EV or you’re thinking about buying one, you’ll probably want to get solar panels and an EV charging port for your home.
These home solar panel installations make it easy to charge your electric vehicle without the hassle of driving to and sitting at a charging station while your car charges. But how many solar panels do you need to charge your electric car? Read on for the answer...
Limited EV Charging Options
With the ever-expanding number of electric vehicles on the road – there still aren’t enough EV charging stations available to the public. While this might change in the future, at this time it’s almost a necessity to have a charger at home. And the most cost-effective way to do this is by using solar panels in conjunction with your charging station.
If you don’t have solar power, you’re at home charging stations will be drawing energy from your local electrical grid. Obviously, the cost for this electricity will be at the same rate as any other electricity your home uses.
Using an average cost of $0.11 cents per kilowatt hour, the Department of Energy estimates that the cost of fully charging an electric vehicle with a 70 mile range would be about the same as running an air conditioner for six hours.
And in the long run, it uses about as much power over the course of the year as an electric water heater. Even so, powering your EV using solar panels can be a very smart, cost-effective solution for both solar panel owners and EV owners.
While it’s possible that your current solar panel system generates enough electricity for your home and a new electric vehicle, it’s also possible that you’ll need to install additional panels to fully power your car with solar.
To figure this out, you want to account for the size and model of your electric vehicle, the capacity of the battery and the efficiency of your solar panels. It’s not as hard as it sounds and we’ll help you understand this in a moment...
EV Charging Systems and Solar Panels
Combining an EV charging station with your home solar system offers a number of advantages, including charging your EV for less. If you’re installing a solar panel system to power your electric car, you’re going to need this kind of combined set up.
One important part of this overall combined system is the solar inverters. Before the energy being generated by your solar panels can be used by your homes appliances and devices, it has to first be converted from DC (direct current) to AC (alternating current). The same applies when you’re fueling your EV with solar power. Fortunately, SunPower panels include the micro-converters required to make this conversion.
The Size of The Battery in Your EV
Just how much electricity will actually need for this recharging process? If you underestimate your power needs, you may have trouble charging your car from just solar and would need to also draw power from your utility company.
To begin with, the amount of electricity you will need to power your EV depends largely on the battery capacity. The battery capacity in an EV is measured using kWh (kilowatt hours).
This measurement can range anywhere from the lower 20's on up to 100 or higher. For instance, while a BMW i3 battery has a capacity of only 33 kWh, and upgraded Tesla Model S has a battery with a capacity of 100 kWh. The larger your battery capacity, the more electricity you’ll require (which still isn’t a ton).
How Many Solar Panels to Charge an Electric Car?
As pointed out above, the number of panels specifically needed for charging an EV will depend on the size of your vehicle’s battery. But for the purpose of considering this question, we’ll use the standard Tesla Model S as a baseline for estimates. This particular Tesla has a battery with a 75 kWh capacity. Your specific needs for your particular car may be different from this but you can find that information on your manufacturer's website.
So, how many solar panels do you need to charge an electric car? First, look at the amount of energy that an individual solar panel can produce. This quantity of energy production is largely dependent upon the size and efficiency of the solar panel, as well as the material from which it is made. If you don’t have panels yet, SunPower panels have the highest efficiency and longest warranty.
The average 250 W solar panel can generate around 30-40 kWh of AC power each month. Let’s make use of the lower number (30 kWh) in our calculations.
Given that single, low output solar panel produces roughly 1 kWh per day of AC electrical power, this would indicate that you will need to install as many as 75 solar panels to generate electricity to power your Tesla Model S each day – assuming that you start the charging process with a battery totally drained of electricity.
However, since the average driver will travel approximately 37 miles a day – this translates to roughly 12 kWh of electricity. With that in mind, a much more realistic set would require approximately 12 solar panels. And even this is still a conservative estimate that’s based on the use of low output solar panels.
If you choose high efficiency solar panels, the total number of panels you will need for charging your EV may drop even further. In addition to this, if you drive less than 30 miles a day, the number of panels would drop even further still.
So a realistic appraisal of not only your car battery capacity – but also use of your car and your solar panel efficiency – can significantly impact the number of solar panels you actually need. The rough amount for most cars is between 6-12 additional panels.
Plan for the Future Now
If you’re planning to install solar panels on your home, and you think you may get an electric vehicle one day, it's a good idea to oversize the system now. Even if you don’t get an EV, this will ensure you’re not using power from your local utility company and keep your true-up bills low.
At the end of the day, solar panels are the most cost-effective way to power your EV. And until there’s as many charging stations as there are gas stations, solar panels with a home charger are the best option for charging your car battery.
Based on current technology, you’ll find that anywhere from 6-12 solar panels will produce enough power to support your vehicle's daily needs. And by installing solar panels to charge your car, you’ll save money and help to protect the environment. Further, it’s a win-win and if you use SunPower panels because we offer financing options that often cost no money out of pocket.