“It’s Crazy Sunday! This afternoon, Europe will experience negative electricity prices”
That does NOT= all the time, only when it blows in the North Sea and the sun shines over land.
PS> An idea has been floated in Norway to spend the excess power generated at such time to pump water back up to the reservoirs for use to produce hydroelectric power when it doesn’t blow and/or the sun doesn’t shine. (So far the infrastructure to do so doesn’t exist, though)
What IS done is to shut down hydropower production in Norway and import power from where there are excess, thus saving water in the reservoirs.
PS> you may call this a “giant battery” storing excess power in the form of water for electricity production when it is most needed.