[dtech]

When there is a lot of wind and sun simultaneously there is effectively too much electricity supply on the net, and day-ahead prices drop negative. This is partially fueled by flat subsidies per unit produced (has been fixed for a while for new installations), so producing when there's oversupply can still be profitable. Also most households have a flat energy rate and can amortize their energy usage over the year, so they will always keep their solar panels on even if the energy is less than worthless.

US pricing works very differently, especially in Texas.