Spain’s grid issues urgent blackout warning as dangerous voltage swings threaten power supply

• A massive blackout struck several European nations in April.
• Dangerous voltage swings have now returned to the Spanish grid.
• The recurring crisis highlights systemic vulnerabilities in renewable-heavy systems.
• Officials are urgently implementing measures to stabilize the fragile grid.

Just months after a massive blackout paralyzed the Iberian Peninsula, Spain’s grid operator is sounding the alarm again. The same dangerous voltage swings that caused Europe’s most significant power failure in over two decades—stranding commuters, crippling hospitals, and plunging millions into darkness on April 28—have returned. The recurring crisis raises urgent questions about the stability of a power system increasingly reliant on intermittent renewable energy.

Spain’s grid operator, REE, has detected steep voltage swings in the system over the past two weeks that are capable of affecting power supply. In a document sent to market regulator CNMC, the operator urged swift technical changes to be implemented to avoid any such impact. The situation is so pressing that the CNMC is calling a public consultation to adopt urgent, provisional measures to stabilize the system before a more permanent solution can be found.

The regulator’s statement was honest about the risk. “According to the information provided to the CNMC by the system operator, the rapid voltage fluctuations recorded in the last two weeks, even though the voltages are always within the established margins, can potentially trigger demand and/or generation disconnections that end up destabilising the electrical system,” it said.

This alarming development comes less than six months after the April blackout, which a European report confirmed was the first known blackout caused by excessive voltage. That event paralyzed cities and stranded people on trains across the Iberian Peninsula, serving as a brutal wake-up call about grid vulnerabilities.

A system on the brink

The recent voltage shifts are reportedly occurring during times of low demand and high solar power production. The grid operator’s document linked the problem to abrupt changes in scheduled production, particularly with renewable power plants, as well as the response time of plants meant to regulate voltage. This highlights a critical weakness in the transition to green energy. While traditional power sources like natural gas and nuclear continually help regulate the grid’s voltage, most wind and solar plants currently do not.

This inherent instability in renewable-heavy systems was exposed during the April collapse. Investigations ruled out cyberattacks, instead pointing to systemic vulnerabilities. The blackout began in Spain, where renewables account for more than half of electricity generation.

The push for a quick fix

In response to the new threat, the grid operator has proposed a series of urgent changes. These measures are designed to boost the ability to manage voltage and include requiring more thermal power plants, such as natural-gas fired plants, to be available in reserve. The goal is to create a buffer against the unpredictable swings of solar and wind generation.

Due to the urgent nature of the situation, the regulator plans to implement these changes following a brief, five-day period for public feedback. The changes will remain in effect for 30 days but may be extended as needed, indicating that officials view this as a persistent, long-term challenge rather than a one-off glitch.

The fact that these dangerous voltage oscillations are reappearing so soon after a historic collapse suggests that the underlying issues were never fully resolved. It reveals a system struggling to maintain basic stability while being pushed toward an ever-greener, and potentially more fragile, future.

This recurring crisis forces a difficult conversation about energy realism. It underscores the non-negotiable need for reliable backup systems and a balanced energy mix that includes always-available power sources. For the millions who lived through the darkness in April, the latest warnings are more than a technical bulletin; they are a reminder that a modern society cannot function without a resilient and predictable supply of electricity. The lights are on for now, but the grid is clearly signaling that it is still standing on shaky ground.

Sources for this article include:

Reuters.com

Bloomberg.com

News.Sky.com