Solar Expansion for EV Owners: Offset Your Charging Costs

In Short: EV owners see a 30 to 50 percent spike in electricity usage after charging, but a single NEM expansion kit can offset roughly half that extra draw, bringing your true up bill back in line.

You bought solar. You saved money. Life was good. Then you bought an electric vehicle.

The first true up bill after getting an EV hits different. Suddenly that $0 charge is a $200 bill, or $400, or worse depending on your utility and driving habits. The solar system that perfectly matched your old lifestyle now feels undersized.

Here is what most EV owners do not realize: California NEM expansion rules let you add up to 1 kW (or 10% of your existing system, whichever is greater) without losing your existing rate, and a single plug in solar kit can recover a huge portion of those extra charges.

The EV Charging Reality

A typical EV adds 3,000 to 4,000 kilowatt hours of annual electricity demand. If you are charging at home five nights a week, that is roughly 250 to 350 kWh of extra draw per month on average.

Here is where it gets interesting. Your rooftop solar was probably sized around your pre EV electricity consumption. It still produces the same amount of energy. But now you have a larger baseline draw. The excess generation that used to push energy to the grid (earning NEM credit) now gets consumed by your EV charging.

The math works against you until you expand.

How NEM Expansion Solves This

A single NEM GO kit generates approximately 1,500 kWh per year. That is not a full replacement for an EV annual consumption, but it covers the sweet spot: roughly 35 to 50 percent of the extra electricity an EV adds to your home.

With PG&E NEM 2.0 rates around $0.33 to $0.35 per kilowatt hour, that works out to roughly $495 to $525 per year in savings. SDG&E customers see rates around $0.35 to $0.38 per kWh, or about $525 to $570 per year. SCE customers are looking at $0.18 to $0.20 per kWh, or about $270 to $300 per year.

That is real money. That is the difference between getting an EV and immediately saving money versus years of slightly higher electricity bills while you wait to break even on the EV purchase itself.

Installation and Integration

Here is what makes this actually doable for most EV owners: the plug in solar expansion model. NEM expansion kits like NEM GO plug directly into a dedicated outdoor GFCI outlet on the side of your house. No roof work. No contractor scheduling. The panels ground mount in a yard or patio, and they connect to your home existing wiring.

Your EV charger and the solar expansion panels both pull from the same grid connection. During peak generation hours, the panels offset both your home baseline and your EV charging draw. During cloud cover or nighttime, you are charging from the grid like any other EV owner. It is seamless.

You do need a dedicated circuit for the solar panels (its own breaker, nothing else on it). If you do not already have one, electrician work typically costs $200 to $400 and is straightforward and quick. Most homes built in the last 20 years have plenty of spare breaker capacity. It is rarely an issue.

The Real Math

Let us work through a realistic scenario. You have a Tesla Model 3 and you charge at home four nights per week. That is roughly 12,000 miles per year of home charging at roughly 4 miles per kWh, totaling about 3,000 kWh annually.

Your utility is PG&E on NEM 2.0. Your rooftop solar used to handle most of your baseline consumption and your true up bill was close to $0. Now that extra 3,000 kWh of EV charging pushes your true up to roughly $990 per year (3,000 kWh at PG&E effective NEM 2.0 rate of around $0.33 per kWh).

You add a NEM GO system. It generates 1,500 kWh per year. That solar generation offsets 1,500 kWh of your grid consumption at the same rate. Your new true up bill drops to roughly $495 per year instead of $990.

That is roughly $495 per year in savings on an investment of $1,799 with the Spring Sale coupon. Payback: about 3.6 years. After that, it is pure savings for the remaining 20+ year lifespan of the panels.

Compare that to the 7 to 10 year payback on your EV itself. The solar expansion pays for itself in less than half the time.

Why Nobody Talks About This

Most solar installers sell large roof additions that cost $10,000 to $20,000. They do not mention NEM expansion kits because the commission on a $1,799 system is small compared to a massive roof project. Your installer is not lying or hiding anything. They are just not incentivized to bring it up.

Most EV salespeople do not mention solar expansion at all. It is not their focus. They are there to sell you the car.

That means the knowledge gap falls on you. And that is exactly why Bright Saver exists. We are a 501(c)(3) nonprofit focused on making plug in solar affordable and accessible. We do not make more money if you buy a bigger kit. We are here to make sure you know the option exists.

Your Next Step

If you own an EV and rooftop solar, take five minutes to explore how much a solar expansion could save you. Check out our NEM expansion guide to understand your current setup and what expansion looks like.

Then use our free solar savings calculator to see the actual numbers for your utility, your electricity consumption, and your home. See what that $270 to $570 per year in savings could mean for you over the next 20 years.

The Spring Sale is happening now. NEM GO costs $1,799 with coupon SpringSale, down from the regular price of $2,199. Get your personalized estimate and find out if solar expansion makes sense for your EV charging costs.

Last updated: March 2026