Spain’s government has laid fault for the massive April 28 blackout squarely on its grid regulator and private utilities, following a 49-day investigation into the cascading failure that plunged the Iberian Peninsula into darkness. According to a report led by Energy and Environment Minister Sara Aagesen, at least two voltage surges triggered a chain reaction of automatic shutdowns across power plants and regional networks. The sudden frequency and voltage swings overwhelmed the system’s ability to stabilize, disconnecting nearly 60% of the power supply within seconds.

The probe specifically faulted Red Eléctrica de España (REE), the national grid operator, for miscalculating the need for thermal power stations during peak demand. REE reportedly decided not to bring a key voltage-regulating plant online, erroneously judging it unnecessary. In parallel, private utilities such as Endesa, Iberdrola, and Naturgy were criticized for improper automatic disconnections and failure to manage reactive power, essential for maintaining voltage stability.

The blackout left some 60 million people across Spain and Portugal without electricity, halting trains, disrupting airports, and plunging traffic systems into chaos. According to the government, the interruption lasted several hours before full restoration was achieved the next morning. Importantly, the inquiry ruled out a cyberattack as the cause. While the National Cybersecurity Institute had initially investigated that possibility, no evidence was found to support it.

The government’s report calls for sweeping reforms: enhanced oversight, tighter infrastructure investment, improved reactive power management, and bolstered cybersecurity. It warns that legal and administrative actions may follow against REE and several power companies. This crisis underscores the fragility of modern grid systems, especially amid rising dependency on renewables. Spain’s grid relies heavily on solar and wind, which provide less mechanical inertia, reducing its ability to absorb sudden shocks. Limited interconnections with the rest of Europe, roughly 3% compared to the EU target of 15%, further compound the instability.

Aagesen emphasized that the outage resulted from technical shortcomings and “bad planning,” rather than external interference. In response, the government is fast-tracking a capacity market and reinforcing network investments, including energy storage and flexible backup options, to prevent a repeat of the calamity.