How the estimate works
Monthly miles are multiplied by the vehicle's energy consumption to estimate electricity delivered to the battery. The calculator then divides by charging efficiency. For example, a 10% charging loss means 90% of electricity drawn from the home reaches the battery. Grid energy is multiplied by the electricity price you enter.
The EPA and DOE display EV consumption as kWh per 100 miles because a consumption measure connects directly to energy use and cost. You can find that value on the electric-vehicle fuel economy label. Actual consumption can differ with speed, temperature, cabin cooling, tires, cargo, and driving style.
Choose an electricity price that matches charging
This tool does not guess an APS, SRP, or municipal utility rate. If you have a time-of-use plan, enter the $/kWh price for the window in which charging will occur. If you use an average bill rate, remember that fixed service charges may not rise when you add EV charging, while usage-based adjustors may. The result is therefore a planning estimate rather than a bill forecast.
Check the current utility guidance before setting a vehicle timer. APS publishes its own EV charging windows, and SRP's residential plan comparison shows the current time periods for available plans. Your enrolled plan—not a generic Arizona schedule—determines the relevant price and hours.
Gas comparison and solar
The optional comparison uses only the gas price and MPG you enter. It compares fuel energy cost, not total ownership cost. Vehicle price, insurance, maintenance, depreciation, charger hardware, and electrical upgrades are outside the model.
Rooftop solar electricity is not automatically free. Charging can replace an export that would otherwise earn a bill credit, and system ownership has its own cost. To explore a solar-charging scenario, enter the value per kWh that reflects the energy you would otherwise export or buy; this calculator does not assume a zero solar rate.
Frequently asked questions
Should I use advertised range and battery size?
Use kWh per 100 miles when possible. Dividing battery size by advertised range can mix usable and gross battery capacity and may not match real-world driving.
What should I enter for charging loss?
Use measured wall-to-battery data when available. Loss depends on the vehicle, charger, power level, temperature, and battery conditioning, so the example value is not a promise about a particular setup.
Does the estimate include demand charges?
No. If your rate includes demand charges, charging power and overlap with other home loads can matter in addition to total kWh. Review the current utility tariff or your bill before making a scheduling decision.