One of Europe's most severe blackouts grounded flights, paralyzed metro systems, disrupted mobile communications and shut down ATMs across the Iberian Peninsula.

Even as electricity was restored across Spain and Portugal after a daylong blackout, residents tried to make sense of 18 hours of the “insanity.”

As factories, stores and hotels across Spain and Portugal gradually returned to normal on Tuesday after a huge blackout the day before, business associations and companies began counting the cost.