Stormy sun could knock out power grids

An upcoming cycle of stormy solar activity risks causing damage to electrical transformers and threatening vulnerable energy infrastructure around the globe, a report by an insurance group says.

The sun follows a predictable 11 year activity cycle, with the next period of stormy activity expected to begin in 2012-13.

The report by German insurance group Allianz (ALVG.DE) said a high impact solar storm, not easily predicted due to its recorded rarity, could cause blackouts and economic losses of over $1 trillion and that the worst case scenario would be even worse.