What does it cost if a guest charges their car?

The costs are the number of kWh the battery needs, times your own kWh rate. A car charging from half-empty to full often uses 25 to 30 kWh per session, so at 30 cents per kWh you pay 9 euros per charging session, and when charging multiple times in a week that adds up to 20 to 30 euros. Because the meter cabinet does not distinguish between household power and charging power, you usually only notice this on the annual bill. A separately metered charging point places these costs with the guest instead of with you, though that is only worth it if you regularly rent to guests with an electric car.