According the Institute for Energy Economics and Financial Analysis (IEEFA), February 2020 saw renewable energy (including utility-scale solar, wind, and hydropower) generate more electricity than coal plants in the United States — a first-time occurrence during a winter month.
According to data from the U.S. Energy Information Administration’s (EIA’s) new hourly electric grid monitor, renewables generated 56,981,597MWh of electricity during February while coal produced 54,733,731MWh.
The first time renewables outproduced coal was in April 2019. As IEEFA noted then, April 2019's results were somewhat influenced by the industry practice of taking coal plants offline during lower-demand seasons (spring and fall) to perform maintenance and upgrades in preparation for higher energy demand during the summer and winter months.
To learn more about the underlying factors, future trends, and more, read the original report from IEEFA.