A typical solar panel is 250 watts and will generate about 30 to 42.5 kWh of energy on a monthly basis. On the lower end of that, you’ll be making about one kWh of energy per day. This means you’d need around 75 solar panels to charge a Tesla model S to 100% every day if it starts at 0%. Your EV likely won’t be as low as 0% every time you charge it, making this a conservative estimate.
If you install high-efficiency SunPower panels, which are rated up to 420 watts per panel, you could generate up to 54 kWh of energy per month or 1.8 kWh per day, which means you would only need 42 panels
The average travel distance for a driver is 39 miles per day, equating to about 12 kWh of electricity. As such, you’ll need 12 solar panels (that have standard efficiency) for your charging needs.
However, if you drive less than the average 39 miles per day and own more efficient solar panels, you’ll need fewer than 12 panels for your EV charging needs. Investing in high-quality, efficient solar panels is better in the long run.
Additionally, the average home in the U.S. requires between 19 and 34 solar panels to fully cover electric bills. You should expect this number of panels to increase with the addition of an EV to charge.