At 12:33 p.m. on April 28, swathes of Spain and parts of Portugal were plunged into darkness: trains were stranded, phone and internet coverage faltered, and ATMs stopped working.

The electricity blackout across the Iberian Peninsula is believed to be one of the worst in Europe's history.

While most power was restored by the next morning, weeks later the investigation into the blackout is ongoing.

Last week, Spain's energy minister Sara Aagesen said so far it was clear an abrupt loss of power at a substation in Granada, followed by failures in Badajoz and Seville, led to a loss of 2.2 gigawatts of electricity, but that the precise cause was unknown.

In the wait for answers, some have pointed the finger at Spain's high reliance on renewables and reignited debates over plans to phase out nuclear power by 2035.

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Spain is one of the leaders in Europe's green energy transition and has ambitious targets for renewables to provide 81% of its electricity by 2030. Last year they accounted for a record 56% of the country's electricity and

© Deutsche Welle