Six months after my solar install, I bought a used 2022 Chevy Bolt EV. I want to be clear that I did not buy it to “complete my solar setup” — I needed to replace my aging Civic and the numbers on the Bolt worked out. But immediately, everyone started saying the same thing: “Oh, now your solar pays for your gas too!” That’s mostly true, but the full picture is more interesting than that.
My Baseline: Before the EV
Pre-EV, my household used about 14,400 kWh per year — a number I had pinned down precisely after doing a thorough DIY home energy audit before I ever called an installer. My 10.4 kW solar system was designed to offset roughly that amount — my installer sized the system specifically to my usage. In my first 7 months post-install (before the Bolt), I was generating close to 100% of my consumption and banking some credits for winter.
I was spending about $1,850/year on electricity before solar. After solar, my first 7 months suggested I’d net out around $180-220/year in electric bills (mostly winter grid purchases not fully covered by credits).
On gasoline for the Civic: roughly 12,000 miles/year at 32 mpg average = 375 gallons. At $3.40/gallon average = $1,275/year in gas. Total energy spend: about $3,125/year.
Adding the Bolt: What Changed
The 2022 Bolt gets about 3.5 miles per kWh in real-world mixed driving (EPA says 3.7, I’ve averaged 3.5 over 8 months and about 9,000 miles). At my driving rate of roughly 12,000 miles/year, that’s about 3,430 additional kWh per year in electricity consumption.
That’s a 24% increase in my household’s electricity needs — from 14,400 kWh to approximately 17,830 kWh. My solar system was designed for 14,400. I now have a meaningful gap.
On my current setup, solar covers about 70% of my total energy needs (house + car). I’m buying more grid electricity than before — particularly in winter when production is lower and I’m charging at home every night.
The Financial Reality
Let me run the numbers honestly:
Electricity for driving: 3,430 kWh × $0.12/kWh (my blended rate) = $412/year. That replaces $1,275 in gasoline — a savings of $863/year just on fuel. Even without solar, switching to an EV saves me money at Ohio electricity prices.
But with solar, it’s better: my system produces surplus in summer that I was previously sending to the grid for $0.05/kWh (AES Ohio’s export rate). The Bolt soaks up that surplus instead. I’m effectively driving on solar power I was previously giving away cheap. That changes the economics meaningfully.
On a Time-of-Use rate (which I’m on), I also charge off-peak at $0.07/kWh. Combined with solar surplus during the day, my effective fuel cost is somewhere around $0.02-0.04/kWh equivalent. I don’t have exact numbers because it’s genuinely hard to track what electrons came from where, but my overall electric bill has increased by far less than the naive calculation would suggest.
Did Adding the EV Change My Solar ROI?
Yes, actually for the better — with a caveat.
My solar system was originally sized to offset 14,400 kWh. My payback calculation assumed I’d offset those kWhs at retail rates and sell surplus cheap. With the EV, I’m using more of my own production (instead of exporting at low rates), which improves the value of each solar kWh I generate. Self-consumption is worth more than exported power.
The caveat: I’m now buying more grid power in winter for the EV. My December-February grid purchases increased by roughly $45-60/month compared to my first winter. That wasn’t in my original solar ROI calculation.
Net effect: the EV made my solar slightly more valuable but also created a demand I can’t fully meet. If I had sized my system for EV charging from the start, I’d probably have added 2-3 kW — another $4,000-6,000 in panels. Some people add a second array for the car. I’ve decided to live with the current setup for now and revisit if I get another EV.
The Level 2 Charger Question
I installed a Level 2 charger — a 240V outlet and a 32-amp EVSE — when I got the Bolt. The Bolt’s onboard charger is 7.2 kW, so 32 amps at 240V gets me about 25 miles of range per hour of charging. That’s plenty for overnight charging.
For most people, the charger hardware itself isn’t the expensive part — it’s the electrical work. My electrician charged $380 to run a 240V line from my panel to the garage. The charger itself was a home Level 2 EV charger I picked up for around $200. Total: under $600, which I’ll recover in the first few months of gasoline savings.
One thing I do: set the Bolt to charge on a schedule, starting at 11 PM when my off-peak rate kicks in. This matters for winter when I can’t rely on solar. In summer, I try to charge in the afternoon when my panels are producing well — I plug in when I get home from work and let it charge from 4-7 PM, which is typically still good production time and before my utility’s peak rate window.
Should You Size Your Solar System to Include an EV?
If you’re buying solar and you plan to get an EV within the next few years, yes — tell your installer and size the system accordingly. Adding capacity at initial install is cheaper than adding panels later (you don’t pay the per-project costs twice, and you avoid the possibility that your panel brand gets discontinued or the inverter is a different generation).
A rough rule of thumb: for every 10,000 miles driven per year on an EV, add roughly 3,000 kWh to your solar sizing calculation. If you drive 15,000 miles annually, that’s about 4,300 kWh. Divided by your local peak sun hours (Columbus: 4.2), that suggests you’d need roughly 2.8 kW of additional solar capacity. Call it 3 kW to be safe, which at $2.50/W is about $7,500 before the ITC — or $5,250 after the 30% credit.
The Bottom Line
Solar + EV is a genuinely good combination. You use more of your own production, you fuel a car on electricity you generated, and you reduce your total energy spend substantially. But it does change the math — specifically it increases your electricity demand in ways your original solar sizing may not have anticipated. Go in with eyes open, size appropriately if you know an EV is coming, and use time-of-use rates to maximize the value of off-peak charging. My total energy spend (house + car) went from $3,125/year to roughly $750/year after solar and the EV. That’s real money.