An electric vehicle changes residential solar economics more than almost any other household variable. The reason is simple: an EV converts gasoline spending — which a solar system cannot offset — into electricity spending, which it can. Adding an EV to a household effectively raises the displaceable electricity bill, which makes every additional kWh of solar production worth more.
The conversion math
A typical 2026 EV consumes 0.28-0.34 kWh per mile driven, with efficient sedans (Model 3, Ioniq 6, EV6 RWD) on the lower end and pickups and SUVs on the higher end. Take 0.30 kWh/mile as a useful average.
A household that drives 12,000 miles/year per EV adds 3,600 kWh/year of electricity load. At a national-average effective rate of 16¢/kWh, that is roughly $580/year of new electricity spending — but it replaces $1,400-1,800/year of gasoline spending at $3.50/gallon and 30 MPG. The EV alone saves $800-1,200/year before any solar.
Layer in solar: if you produce that 3,600 kWh on your roof, the electricity portion of EV operating cost drops to roughly zero. Total annual driving cost falls from $1,400-1,800 (gas car) to essentially nothing (solar-charged EV) — net of marginal grid use during cloudy weeks.
How this changes solar sizing
Most installers size solar to current consumption. If you are planning to buy an EV within the system's lifetime — or already drive one — the right number is current consumption plus expected EV charging load.
Concretely: a household with 11,000 kWh/year current consumption planning to add one EV at 12,000 miles/year should size to 14,600 kWh/year of production. That difference is roughly 3 additional kW of system size, or about $9,600 in additional install cost — which is paid back by the gasoline displacement alone in 7-10 years before any solar export credits.
The time-of-use trap
EV charging is the single biggest household load most homes ever encounter. A Level 2 charger at 40 amps pulls 9.6 kW continuously — more than every other appliance combined in most homes. When that charge happens matters enormously on time-of-use rate plans.
Charging during peak hours (typically 4-9 PM) can cost 35-55¢/kWh in California, 25-35¢/kWh in the Northeast, and 15-22¢/kWh elsewhere. Charging during super off-peak hours (overnight or midday) can cost 7-15¢/kWh in the same utilities.
The optimal pattern with solar is to use midday solar production directly when possible (a Saturday-afternoon charging session is essentially free), and to schedule weeknight charging to the lowest TOU window (usually midnight-6 AM). Most EVs and Level 2 chargers support this scheduling natively.
What about cars in the driveway during midday?
If your EV is home during the workday — remote workers, retirees, multi-EV households where one stays — direct solar charging is the cleanest economic outcome. Solar production is consumed instantly without any export-credit haircut, and grid imports overnight can be minimal.
If both cars leave at 8 AM and return at 6 PM, the midday production is exported (at whatever your local export rate is) and the evening charging session imports from the grid (at the import rate). Under full retail net metering, the spread is zero and the math is unchanged. Under net billing or NEM 3.0, the spread is real — which is where battery storage starts to matter for EV households.
The combined back-of-envelope
For a typical US household considering both solar and an EV in 2026:
- A gas car at 30 MPG and 12,000 miles/year burns $1,400-1,800 in fuel.
- An EV at 0.30 kWh/mile and the same miles consumes 3,600 kWh/year, worth $580/year on grid power at national-average rates — or roughly $0 if produced by sufficiently-sized rooftop solar.
- The added solar capacity required is ~3 kW, costing roughly $9,600 to install in 2026 (no federal credit).
- The added solar capacity has a simple payback against gasoline displacement of about 5-7 years, separate from any other solar economic argument.
This is why "solar + EV" is the strongest residential clean-energy economic argument in the post-25D era. Each makes the other better. A household that owns both, sized correctly, comes closer to a 10-year combined payback than either alone in 2026 conditions.
Bottom line
If you drive an EV or plan to within the lifetime of your solar system, size for both loads, schedule charging for solar hours or off-peak windows, and treat the gasoline savings as a separate and additive payback stream from the electric bill savings. The combined math is materially better than either alone — and is one of the few cases where 2026 economics still compete with the pre-2026 federal-credit era.