Germany has sunk some major investments into renewable energy over the past few years, and it paid off for consumers over the holidays when an abundance of wind power meant households were actually paid to use electricity.
Power demand is low over the holidays, when fewer businesses are open, and warm weather (it hit 10 C in Berlin on Christmas Day) and strong gusts meant there was more wind power available than there was demand for it.
Prices dropped as low as -61€ (-$91 CA) per megawatt hour on the European Power Exchange (EPEX).
This isn't actually a strange occurrence in Germany. As of November 2017, prices dipped into the negatives over 100 times last year, according to Energy Brainpool, a German consulting agency.
And it happened again on New Year's Day, when at around 6 a.m. local time, 100 per cent of the country's energy was covered by renewables. The addition of coal and nuclear power generated a surplus, German-language paper Süddeutsche Zeitung reported.
SMARD, a German electricity market data site, reports at midnight on Christmas Eve, consumers were using 42,000 megawatt hours of electricity, while 53,000 megawatt hours were being generated (30,000 megawatt hours coming from wind power).
Because Germany hasn't yet found a way to reliably store renewable energy, or to quickly shut off coal or nuclear power when renewables unexpectedly ramp up, they need to customers to consume more during times of oversupply. That or the energy needs to be exported to nearby markets.
"We have a lot of stress on the grid," Ulrike Hörchens, a spokeswoman for Tennet, a large grid operator in Germany, told the New York Times.
Unfortunately, the negative cost doesn't mean energy consumers suddenly get a direct deposit from their energy company in the bank.
Instead, it translates to a discount on their bills over the course of the year.
The German government has pledged to phase out nuclear power by 2022 and have 80 per cent of power come from renewable sources by 2050.