Spain-Portugal outage: How can an electricity network go down in five seconds? Explained

General power outages in Spain and Portugal highlight grid vulnerabilities due to various causes like solar and wind power reliance.

General power outages like the one that hit Spain and Portugal this week can have multiple causes but the blackout highlighted how vulnerable the regional system on the Iberian peninsula can be.

The electrical grid is a backbone with complex branches consisting of thousands of interconnected components.

"The grid operators must carefully analyse massive amounts of real-time data like frequency shifts, line failures, generator statuses and protection system actions to trace the sequence of events without jumping to conclusions," Pratheeksha Ramdas, senior new energies analyst at Rystad Energy, told AFP.

Outages are often caused by a sudden shutdown of a source of production like a power plant due to a technical fault or a fuel shortage supplying thermal power plants.

In recent years, natural disasters such as storms, earthquakes, forest fires, extreme heat or cold sometimes intensified by global warming have damaged infrastructure or created peaks of demand for heating or air conditioning.

Other possible causes include overloads on high-voltage power lines, which force excess electricity to move to other lines, and cyberattacks, which Spain and Portugal have ruled out, but which are an increasingly mentioned threat as networks become more digitised.

In Spain on Monday (April 28, 2025) evening, grid operator REE mentioned a "strong fluctuation in power flows, accompanied by a very significant loss of production".