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It's still not earning you money to spend electricity because you still have to pay the transfer fee which is around 6 cents / kWh but it's pretty damn cheap nevertheless, mostly because of the excess in wind energy.
Last winter because of a mistake it dropped down to negative 50 cents / kWh for few hours, averaging negative 20 cents for the entire day. People were literally earning money by spending electricity. Some were running electric heaters outside in the middle of the winter.
Interesting. In the UK we have a fixed standing charge per day (about 45p), so when the price goes negative it is in your interest to use as much as you can. The most negative I've seen is -10p/kWh, but most of the time it's fractions of a penny.