The grid operators needed more than a day to fully restore the power supply in Spain and Portugal. One of the circulating theories is that excessive solar power caused the blackout. Is that true?

Spain's government said it had asked private energy companies for "maximum collaboration and transparency" to help identify the cause of the outage.

The blackout across Spain and Portugal knocked out communications and transport systems, shut down industry and offices and brought commerce to a virtual standstill. The blackout could have shaved 1.6 billion euros ($1.82 billion), or 0.1%, off GDP, Spain's business lobby estimated.