The sweeping power outage that hit Spain and Portugal this week has raised questions about the electricity grid in a region not normally known for blackouts.

Electricity has returned to most of Spain and Portugal but with continued disruptions on the second day after an unknown failure caused a massive blackout across much of western Europe.

While it may be tempting to blame the unprecedented power outage that hit the Iberian peninsula this week on the rapid growth of wind and solar power in Spain, reliance on renewables is not to blame.