The major power outage on the Iberian Peninsula in April was caused by “overvoltage” in the grid, which led to a “chain reaction.”

This was stated in a report by the Spanish government, AFP reported.

The causes of the power outage are “numerous,” said Minister of Ecological Transition Sara Aaagen after a cabinet meeting.

She explained that on that day, the system “did not have sufficient capacity to control the voltage.”

Overvoltage occurs when there is too much electrical voltage in the grid, which overloads the equipment. It can be caused by surges in the grid due to oversupply or a lightning strike, or when protective equipment is insufficient or fails.

When faced with power surges in the grid, protective systems shut down parts of the grid, which can lead to widespread power outages.

Authorities are trying to find answers after a power outage on April 28 disrupted internet and telephone connections, halted train services, closed businesses, and plunged cities in Spain and Portugal into darkness, as well as briefly affecting southwestern France.

Spanish Prime Minister Pedro Sánchez announced the creation of an inquiry commission led by the Ministry of Ecological Transition shortly after the power outage. He also urged residents not to speculate until detailed results were available.

Sánchez warned that the investigation's conclusions could take several months, given the complexity of the incident.

Aaegesen highlighted the role of Spanish grid operator REE and some energy companies, which he did not name, that shut down their power plants “in an inappropriate manner to protect their installations.”

She also pointed to “insufficient voltage control capacity” in the system on that day, due in part to a programming error. The minister stressed that the Spanish grid is theoretically reliable enough to cope with such situations.

Due to these misjudgments, “we reached a point of no return, with an uncontrollable chain reaction” that could only have been controlled if measures had been taken in advance to address the overvoltage problems, she added. | BGNES