At Home, Does it Cost the Same to Charge at 120 V and 240 V?

Yes. The utility already delivers 240 volts to your home. That is split into circuits that use either 120 volts or 240 volts. It doesn’t matter to the utility whether you use 120 or 240 volts. They just sell you electricity in units of kWh. You can run your toaster with 120 volts, but you’ll need 240 volts to run an electric stove, electric dryer, or electric hot water heater. You can charge your car at either voltage, but it will take a very long time at 120 volts. Most people charge their EVs overnight at 240 volts. Charging today’s EVs at 120 volts will take days.