section_path: Causes
section_name: Causes
paragraph_text: Causes
  
  The power failure was caused by a "surge in voltage that the grid was unable to absorb". A combination of technical, structural, and managerial factors contributed. There were two major fluctuations in the electrical grid, the second of which caused Spain's power system to disconnect from the European system and collapse the Iberian electricity network itself. On 17 June 2025, the Spanish government released its report pinning the proximate cause of the outage to small outages concentrated in southern Spain setting off a complicated chain reaction. REE did not have sufficient natural gas power plants on-line at the time. They "made their calculations and estimated that (switching on more thermal plants) was not necessary at this time. They only set it for the early hours of the day, not the central hours."