Portugal Runs on 100% Renewables Dropping Consumer Electric Bills to Nearly Zero for 6 Days in a Row::In total, there were 149 hours of total renewables generation, 95 of which saw the Portuguese grid exporting to Spain
I'm going to go ahead and assume that the article means it comes at zero cost to Portugal, as a country, thus not having to import it. It would be fairly misleading though.
Nope, all of Portugal now only has electric vehicles. No air planes, only zeppelins and hot air balloons. No boats, only floaty arm bands, rafts, canoes, and kayaks.
As I understand, this happens when renewables 'overproduce' and we need to get rid of the power somehow. People can gladly use as much power as they want in that case. Even if someone fills up batteries for free to later sell back into the grid when production normalizes, that is actually very much what we want. It just adds storage capacity and ensures prices will stay low for longer.