Here’s the source:

https://www.ren.pt/en-gb/media/news/portugal-has-been-using-green-electricity-for-over-24-hours

This… actually doesn’t seem like some bullshit accounting. Like, the country actually was running 100% on wind/solar/hydro with ‘combined-cycle natural gas power plants’ as a backup:

“The availability of natural gas power plants ensures the National Electrical System’s necessary service continuity whenever required, whether for market balance, supply security, or occasionally providing a cost-effective production solution, facilitating a safe and sustainable transition to an electrical system increasingly based on renewable production sources.”

This is pretty amazing.