ev · calculator
How much EV owners can save by charging off-peak
A transparent way to estimate annual EV charging value from a utility plan's peak and off-peak prices.
Published
The value of off-peak EV charging depends on three numbers: charging energy, the share that can move, and the price difference between the old and new hours.
Cheapest Hours uses 300 kilowatt-hours per month as a published example. That is roughly 12,000 miles per year at 3.3 miles per kilowatt-hour. If 90 percent of charging can move, the flexible amount is 3,240 kilowatt-hours per year.
Suppose the relevant price spread is 20 cents per kilowatt-hour. Multiplying 3,240 by $0.20 gives an estimated annual energy-charge difference of $648. A 40-cent spread produces $1,296. The calculator lets a driver replace every assumption.
The plan schedule still matters. The charging session must fit inside the cheapest window. A vehicle adding 40 kilowatt-hours through a 7.2 kilowatt charger may need about six hours after losses. If the low-price period lasts only five hours, part of the session may fall into a higher period unless the driver needs less energy.
This estimate is not a complete rate comparison. Fixed charges, baseline tiers, demand charges, taxes, enrollment rules, and changes in non-vehicle use may outweigh part of the charging benefit. Use interval data and the utility’s comparison tool before switching plans.