Sunday, May 8 was a good day for Germany’s renewable energy sources. As Quartz reports, last Sunday Germany’s solar, wind, hydro, and biomass plants generated so much energy, power prices actually went negative. For a period of time, a full 87 percent of the country’s power was supplied by renewable sources, which meant that nuclear and coal plants ended up having to pay commercial customers to use energy.

Conditions on Sunday, May 8 were apparently perfect for renewable energy production: The Sun was shining, and the wind was blowing all day. But even on cloudier, calmer days, Germany is still producing impressive amounts of renewable energy. Last year, the average renewable energy mix was 33 percent, and Germany hopes to reach 100 percent renewable energy by 2050. Germany currently has plans to open new wind power plants, pushing its renewable energy production up considerably.

Though Sunday’s renewable energy output was an all-time high for Germany, it still hasn't surpassed its northern neighbor, Denmark. In general, Denmark is known for its high renewable energy output, and on an extremely windy day in 2015, its wind turbines generated a full 140 percent of the power consumed by the country (surplus power was redirected to Norway, Germany, and Sweden, International Business Times reports). Still, Germany is making great strides in renewable energy production, setting a standard for countries around the world.

“We have a greater share of renewable energy every year,” Christoph Podewils of the German clean energy think tank Agora Energiewende told Quartz. “The power system adapted to this quite nicely. This day shows again that a system with large amounts of renewable energy works fine.”

[h/t Quartz]