Renewable sources of energy such as solar and wind have been outstripping the electricity supply of traditional baseload (coal, nuclear, and some natural gas) power plants during daytime, especially afternoons, in some renewable-leading countries of late. One reason for this is: electricity demand tends to increase during the sunniest (the hottest) hours, and solar power plants generate more electricity when it is sunnier, which is right on cue.
Not perfectly, but solar power production tends to follow electricity demand. This is especially true in the warmer temperatures, since air conditioners (which consume a lot of electricity) are turned up to compensate for the hot afternoon weather.
Importantly, as solar power plants outstrip the power production of baseload power plants, electricity is sold for a lower price than baseload power on the spot market. On April 1 of this year, not even that hot of a day, the price of electricity on the European Electricity Index (ELIX) actually dropped to -0.01.