How many solar panels do you need to charge an electric car?

Electric vehicles (EVs) and solar panels are a dynamic duo that puts money back in your pocket and contributes to lower fossil fuel emissions. Throw in growing solar panel adoption and you might reasonably ask how many solar panels you need to charge your new EV.

The simple answer is that it usually takes 7 to 12 solar panels to charge an EV, depending on the make and model, weather, and your driving habits. Here's a quick breakdown to help determine how many solar panels you need to power your EV reliably.

The first thing you'll want to think about is matching how you typically use your EV with how much electricity it will need to maintain that level of usage. You can think about this in a couple of ways: the amount of electricity required to reach a full charge and the amount of electricity used per mile driven, usually expressed in kilowatt-hours per 100 miles driven (kWh/100 mi). 

You can use the size of your battery to estimate the electricity required to "fill the tank" for your EV. Electric vehicle batteries have relatively large capacities and store between 25 and 100+ kWh. For reference, home energy storage systems, such as the Enphase Energy IQ and the Tesla Powerwall+, store around 13.5 kWh of electricity.

Battery size & range of popular EVs

How much electricity an EV consumes per day, month, or year depends primarily on how far you drive. Your needs will be different if you live in an urban area and drive infrequently than if you live in a suburban or rural area and commute in your car every day. 

According to the Federal Highway Administration, the average American travels nearly 13,500 miles annually. At that level of driving, most EVs will require around 4,000 to 5,000 kWh of electricity per year to operate.

Annual electricity usage of popular EV models

To calculate the number of solar panels required to power your EV, you'll need to know three key data points: 

• How much electricity your car uses annually 

• The total wattage of the solar panels you plan to install 

• The production ratio of your panels, or how well solar panels produce electricity where you live

Once you understand these numbers, you can plug them into the following equation:

Number of panels = system size/production ratio/panel wattage

Let’s do the math for the average American driver:

• A typical EV requires about 4,000 to 5,000 kWh of electricity per year. 

• According to the most recent EnergySage Intel Report, 390 to 400-watt panels are the most frequently quoted solar panels on EnergySage. We’ll use 400 W panels for this example. 

• Production ratios in the U.S. are usually between 1.1 and 1.6 depending on the region; solar panels usually produce more electricity in sunnier climates than they would in places like the Northeast.

Number of panels = 4,000-5,000 kWh / 1.1 or 1.6 / 400 W

Based on this, charging an electric vehicle typically will require 7 to 12 solar panels out of however many you install on your home overall. 

Number of solar panels required to charge popular EVs

Transitioning to electric driving is beneficial in itself. Taking it a step further and charging your EV with solar panels enhances your investments' financial and environmental benefits. 

Charging your EV with solar reduces your electricity bill

In most cases, charging your EV with grid-produced electricity is already cheaper than fueling a gas-powered car. Pairing your EV with solar panels generates even more savings still. It’s possible to completely eliminate your fuel costs when you power your EV with a home solar energy system. 

Charging your EV with solar shrinks your carbon footprint 

Limiting the use of grid-produced electricity when charging your EV is better for the environment. The U.S. grid is getting cleaner but still relies on fossil fuels. Powering your EV with renewable energy reduces your demand for utility energy, lessens your carbon footprint, and contributes to healthier air quality.  

Solar panels can maximize your EV’s potential. Register for a free account on the EnergySage Marketplace to receive custom solar quotes today. Make sure to note that you’d like to power an EV with solar panels, and our network of vetted solar companies will help design a custom system for you that meets your specific needs.