Partly the neighboring country. Between Spain and Portugal there's 10 GW (~20% or peak load) and 100 GWh of storage (enough for a day's worth of consumption).
But that takes time and requires some rebalancing, because much of that capacity is not closest to the producers. It also requires water, which becomes scarcer in the autumn (not the case here).
So the price can and does become negative for a window. “High frequency trading” the spot prices probably contributed to the problem.
But that takes time and requires some rebalancing, because much of that capacity is not closest to the producers. It also requires water, which becomes scarcer in the autumn (not the case here).
So the price can and does become negative for a window. “High frequency trading” the spot prices probably contributed to the problem.