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.

Spain’s nationwide blackout this week has put a spotlight on potential vulnerabilities in its system that may offer warnings to other countries, as rising electrification and clean energy sources place new demands on power grids around the world.