The poster said it's an extra 0.4 cents/kWh, not 0.4 USD/kWh.
Our contract in Sweden is NordPool market price + 0,006 USD/kWh. Typical electricity prices in Sweden is anything from 0,001 USD/kWh to 0.5 USD/kWh, it varies widely day by day. This is what enables people to be able to save by using electricity when it's almost free.
In the cheaper public utility districts here, the per kWh price is only double those rates, with no time of day pricing or similar shenanigans.