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.

Monday’s devastating blackout in Spain is raising questions about the country’s massive reliance on solar and wind power for electricity — and whether the new power sources may have played a role. Spain’s socialist government has faced increasing pressure to explain what went wrong on Monday,