Are you sure it’s only a few minutes at low demand times? I checked a few days in April at your link, and if I’m reading the graphs right, it looks like renewable production exceeded demand for at least several hours in the afternoon for each of the days I checked.

The headline on the original article seems unhelpful and perhaps deliberately misleading, but unless I’m reading the graphs wrong (quite possible!) this also doesn’t seem, like, a 15 minute window at 2 a.m. where unexpectedly strong winds created a temporary blip of excess production.