On April 28, much of Spain and parts of Portugal were plunged into darkness during a major power cut.

Cities including Madrid and Lisbon were hit. Public transport was halted, flights delayed, and digital services went down.

Power was gradually restored overnight, but questions still remain over what triggered the collapse of the national grid.

Some sources indicate that the problem may have been triggered by the disconnection of some solar plants in southwest Spain, but the grid would normally be able to balance this out through regulation.

Spain’s Prime Minister Pedro Sánchez has pledged “all necessary measures will be taken” to prevent similar blackouts in future.