With more Californians driving electric vehicles, many homeowners are wondering if they should install rooftop solar to help power their EVs. The answer is maybe. Solar panels can offset the electricity needed to charge an EV, but whether it’s a cost-effective solution depends on system size, setup and how much power the household uses overall.
In a region like Southern California, where sunshine is abundant and electricity rates are among the highest in the country, solar and EVs can make a powerful pairing, both environmentally and financially.
Home solar panels don’t charge an electric vehicle directly; instead, the solar system feeds electricity into the home’s electrical panel. That energy can power household appliances, charge a vehicle or be exported to the grid. If a homeowner charges an EV during the day while solar panels are producing electricity, most of the energy comes directly from the sun. If they charge at night, they’re likely drawing from the grid, unless the home also has a battery backup system.
According to the U.S. Department of Energy, the average EV uses about 30 kilowatt-hours (kWh) to travel 100 miles. If a driver puts 1,000 miles on their EV per month, they’d need about 300 kWh of electricity on top of their regular household usage. For many, that’s a 25% to 40% increase in monthly electricity demand.
Sizing a solar system for EV charging
Most Southern California homes that go solar install systems between 6 and 10 kilowatts (kW), according to data from the California Energy Commission. But for households with one or more EVs, it’s common to go bigger — 10 to 12 kW or more — to ensure enough capacity to cover both home and transportation needs.
The exact number of panels needed depends on several factors, including driving habits, available roof space and local solar production potential. According to the National Renewable Energy Laboratory (NREL), a 10-kW system in Los Angeles can generate roughly 15,000 kWh per year — enough to cover the average home’s energy use and an EV’s charging needs.
What it costs
The average cost to install solar in Southern California is about $2.75 to $3.25 per watt, depending on the installer and equipment. That puts a 10-kW system in the ballpark of $27,500 to $32,500 before incentives.
Thanks to the federal Investment Tax Credit (ITC), homeowners can claim 30% of their total system cost as a tax credit, reducing the net price by several thousand dollars. Additional rebates may be available through local utilities, including the Self-Generation Incentive Program (SGIP) for battery storage.
Installing a Level 2 EV charger typically adds another $1,000 to $2,000, including labor and permitting. Many Southern California utilities, such as Southern California Edison and San Diego Gas & Electric, offer rebates for residential EV chargers — usually between $250 and $500. More info here.
Return on investment
With utility rates rising across the state, the ROI for solar can be relatively quick, especially when it offsets EV charging. According to SolarReviews, Southern California homeowners can recoup their investment in as little as 6 to 9 years, depending on system size, energy use and utility rates. After that, the electricity is essentially free for the life of the system, which typically lasts 25 years or more.
Drivers who rely heavily on charging at home may save even more. For comparison, 1,000 miles of monthly EV driving might cost $150 or more in electricity if charged entirely from the grid, depending on time-of-use rates and charging habits. Charging with solar can reduce that cost to near zero.
To make the most of solar for EV charging, homeowners need to consider when and how they charge. Charging during the day maximizes use of solar generation. Charging at night could mean pulling from the grid unless a battery is installed to store daytime solar for later use.
Battery systems like the Tesla Powerwall or Enphase IQ Battery can add $10,000 or more to a project but may be worthwhile for households that want backup power or better time-of-use management.
For homeowners considering the switch to solar, it’s worth speaking with a licensed solar installer who can provide a detailed estimate based on actual usage and available incentives. Tools like the California Solar Consumer Protection Guide can help compare options and get multiple quotes.
The news and editorial staffs of Southern California News Group and The San Diego Union-Tribune had no role in this post’s preparation.