Three days ago, in Denmark, prices went as low as -41.37Eur/MWh (where 100Eur/MWh is a common price otherwise).
https://www.nordpoolgroup.com/en/Market-data1/Dayahead/Area-...
At the moment electricity is cheapest (and therefore greenest) in the afternoon. Probably because of solar (partially from Germany).
https://app.electricitymaps.com/zone/DE
It's also great to see how much green energy Spain got recently.