Solar + EV integration
Before comparing anything to solar, you need an honest grid-only baseline. Add your efficiency and rate structure for an exact cost per mile, plus a gasoline comparison.
How it works
Step 1
Your vehicle's EPA efficiency rating, found on its window sticker or fueleconomy.gov, is a good starting figure.
Step 2
Your utility bill or rate schedule will show whether you're on flat pricing or time-of-use.
Step 3
Once you have this number, the cost per mile with solar calculator shows exactly how much a system would improve it.
Knowing your real grid-only cost per mile gives an honest starting point before evaluating solar's benefit. Without this figure, it's easy to either overstate solar's advantage by comparing against an inflated cost, or understate it by not accounting for your actual charger efficiency and rate structure.
A flat electricity rate charges the same price regardless of when you charge, while time-of-use pricing typically charges considerably more during afternoon and evening peak hours and less overnight. Shifting most charging to a scheduled overnight window, which most EVs and chargers support, can lower cost per mile by a real margin even without solar in the picture at all.
A Level 1 outlet loses more energy to heat during charging than a Level 2 home charger, and DC fast charging has its own efficiency profile, so the same driving distance can produce a noticeably different cost-per-mile figure depending purely on which charger delivered the power. This is why the calculator asks for charger type specifically, rather than assuming a single fixed efficiency loss for every charging method.
Electricity's energy-per-dollar advantage over gasoline holds in most US and Canadian markets even without any solar offset, since a gallon of gas contains meaningfully less usable energy per dollar spent than a comparable amount of grid electricity in most regions, per fueleconomy.gov comparisons. This is the underlying reason EV owners see cost savings from day one, before solar is even part of the conversation.
This grid-only figure becomes the reference point for every other cost comparison on this site, whether that's evaluating solar offset savings, calculating a payback period like the cash purchase vs financed payback comparison, or projecting savings over 5 or 10 years. Getting this number right first makes every downstream calculation more accurate.
Compare this figure directly against the EV charging cost per mile with solar calculator to quantify solar's specific benefit, or use it in the annual solar vs grid comparison for a fuller yearly picture. The time of use rate savings calculator approaches the same problem from the other direction.
Questions
At 25 kWh per 100 miles efficiency and a flat $0.15 per kWh grid rate, cost per mile comes out to about $0.043. That's already less than half the cost per mile of a 30 mpg gas vehicle at $3.50 a gallon, even before solar enters the picture.
Yes, shifting most charging to off-peak hours can lower cost per mile meaningfully. Charging 90% off-peak at $0.10 per kWh and 10% peak at $0.32 per kWh brings cost per mile down to about $0.035, compared to $0.043 on a flat rate in the same example.
In most US and Canadian markets, yes. Electricity's energy-per-dollar is generally more favorable than gasoline's, so an EV charging entirely from the grid at typical residential rates usually still costs meaningfully less per mile than an equivalent gas vehicle.
Adding solar offset to the same charging pattern can cut cost per mile by roughly half or more, depending on your solar system's cost per kWh and offset percentage. Check the EV charging cost per mile with solar calculator to see the specific comparison for your situation.
Related tools