The blackout across Spain and Portugal knocked out communications and transport systems, shut down industry and offices and brought commerce to a virtual standstill. The blackout could have shaved 1.6 billion euros ($1.82 billion), or 0.1%, off GDP, Spain's business lobby estimated.

Portugal is supplying electricity to clients from its own sources as power exchanges with Spain remain suspended amid an inquiry into the causes of a blackout earlier this week, the energy minister said on Friday.

Electricity is pulsing through Spain and Portugal again after a massive outage knocked out power in both countries on Monday. So too are questions.