Most Finnish households have a contract which limits the effect of this pricing anomaly (fixed price contracts are quite popular as people see the hourly market rate as risky and unpredictable). However, I do have a hourly market rate based contract myself and tomorrow afternoon/evening with rates of -0,50€/kWh any electricity consumption is going to lower my energy bill - even considering the energy sale commission, taxes and energy transfer fees which I will of course have to pay.
There are two fixed fees households pay, an energy tax of 0,02253€/kWh and a security of supply fee (0,013 euro cents per kWh). These are not affected by fluctuations in the market prices of electricity.