Should You Get a Bigger Solar Panel System if You Plan to Get an EV?

Electric vehicles and solar systems seem to go hand in hand. They both offer an upgrade in efficiency and replace traditional fossil-fueled systems with cleaner, emission-free alternatives. There's also a large overlap in the target audience -- if you're interested in solar energy, you're likely interested in EVs, too.

The data shows that both solar and EVs continue to be adopted en masse by homeowners and drivers. According to data from Cox Automotive, EV sales grew by 11.3% during the second quarter of 2024, with more than 330,000 sold in the US. Similarly, the first quarter of 2024 was the second-best quarter in history for the US solar industry, and solar accounted for 75% of new electricity-generation capacity additions nationwide, according to the most recent data from the Solar Energy Industries Association. For reference, that's roughly double what it was in 2020.

This growth appears even as the American populace's overall interest in EVs and renewable energy appears to waffle.

Despite hiccups, both EVs and solar systems are growing in popularity, and it could be valuable for homeowners to have both. You could generate electricity from the sun to charge your EV, effectively paying very little, if anything, to get around. If you already have a solar system and are getting an EV, can your system handle the new power demands? Or if you have an EV and want a solar system, what do you need to do?

How to get the right size solar system

Assuming you have both a solar system and an EV -- or have one and plan on getting the other -- experts recommend considering the size of your solar system. Adding an EV on top of your home's existing power consumption may be too much for your solar system. You may need to upgrade an existing solar system or plan on getting a bigger one than you initially accounted for.

Sizing a solar system is a bit tricky. It involves many factors, including a home's energy requirements, climate and sunlight in the immediate area, and the efficiency and size of solar panels. From there, a solar installer can crunch the numbers to determine the overall size of a system a home needs and plan for additional electrical demand in the future.

"During the intake process -- that's when our team thinks through the 'future-proofing,'" said Matt Dilorio, chief marketing officer at EmPower Solar, a Long Island, New York-based solar company. "The team will be able to build out a solar system and size, not based on current needs, but future needs. You may not have an EV now, but you might later -- the team can factor that into sizing the system." 

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In an ideal scenario, someone sizing up their options for a solar system would already have an EV, allowing the company to factor the demands of charging it into their initial calculations. Or if you know that you plan to get one in the future, they can plan ahead for the anticipated power needs. 

"Assuming a customer wants to understand how having an EV is going to impact their consumption," said Zack Lerman, EmPower Solar's director of sales, "the math part is pretty simple."

Obviously, that's not always the case which is where complications can arise. 

The electricity demands of an EV

EVs have different electrical consumption and demand, but according to Lerman, an EV should get about 3 miles per kilowatt-hour. Automotive site Edmunds estimates that the average EV will consume 394 kWh monthly. 

"If you think that you'll drive 10,000 miles per year, in my EV, you'll need 3,500 kWh of energy to support that. If you don't have solar coverage for that, we'll ask [a customer] if they want to add it," Lerman said.

Last year, the best-selling EV in the US by a long shot was the Tesla Model Y. Data from the US Department of Energy shows that the 2023 Model Y's fuel economy is about 3.57 miles per kWh (or 28 kWh per 100 miles). This is close to the 3 miles per kWh figure Lerman cited, with other EV models requiring more or less. For a new Model Y owner, assuming 10,000 miles driven annually, you'd need to add roughly 2,801 kWh a year in solar capacity (not accounting for charging loss) to adequately charge your new vehicle.

With these estimates, gauging your EV's electricity needs and preparing or priming a solar system to satisfy those requirements is entirely possible. Naturally, it's easier to do when a solar system is initially installed. Otherwise, more solar capacity (which may include more solar panels) may need to be added to an existing solar system. EmPower even has an in-house tool the team uses to determine how many new panels may need to be added, and other solar companies should be able to offer similar estimates.  

"If you're thinking of getting an EV plus solar, it's really about sizing the system appropriately," Dilorio said. "Have a professional build a model and future-proof your system."

How to plan for growing electricity demands at your home

If you have a solar system and plan to get an EV, it may be apparent that your system needs to be upgraded to account for the additional electricity demands. Other components can be added to a home that may require upgrading a solar system too.

That can include replacing older, fossil-fuel-fed HVAC systems like furnaces or water heaters with newer, electric or hybrid versions. Electric heat pumps or hybrid water heaters, for example, may reduce your gas bill but increase your electricity usage. If you have a solar system providing most or all of your electricity, adding those types of appliances or systems to your home will require some thinking about how your current solar system can meet the new demand levels.

It bears repeating: Thinking about these potential future updates or upgrades to a home during the planning stages, as it relates to a solar system, can make the whole process a lot easier. This is why "future-proofing" a solar system is so important, Dilorio said. "They can factor it all into the sizing of a system," he says, and "that can be everything from an EV to an electric heat pump."

Try to think ahead and aim to "future-proof" your system so that you don't need to do multiple upgrades. Even if the main reason for the upgrade is an EV, think about the other, future electrical needs your home may require outside of this.