Refuelling With Your Own Solar Power: A Sample Calculation and How It Works
Solar panels on the roof for bargain-basement energy costs.
Here’s a sample calculation: A popular photovoltaic system size for the average household is eight kilowatt peaks. This system will supply around 8,000 kilowatt hours (kWh) a year in Germany. On a sunny day, this system would generate around 40 kWh of electricity. A compact electric car consumes around 15 kWh of electricity per 100 km.
In other words, on a sunny day, an 8 kWp photovoltaic system generates enough power for a 260 km drive in the electric car. If you charge the vehicle via the grid, this 260 km range would cost around €12 in Germany. By contrast, if you charge it with your self-generated solar power, the costs would be max. €4.
And this is how it works: When your household appliances are supplied with solar energy and your solar battery is full, there is a surplus of generated electricity. This energy is not fed into the grid – it flows to the wallbox in your garage or carport. For this process, the charging station constantly monitors the electricity generated by the solar panels and your household consumption. The electric car is only charged if there is definitely a set amount of surplus power available. If the surplus electricity falls below the set limit, the charging process is stopped until the limit is exceeded again.