http://www.express.co.uk/news/science/737882/solar-storm-WIPE-OUT-modern-technology-carrington-eventIn 1859, a powerful geomagnetic solar storm blasted the Earth with charged particles, causing spectacular patterns in the sky and auroras visible as far south as the Caribbean. Telegraphs, the closest thing to modern technology at the time, shorted out, causing fires. The occurrence was known as the Carrington Event.
http://www.lloyds.com/~/media/lloyds/reports/emerging%20risk%20reports/solar%20storm%20risk%20to%20the%20north%20american%20electric%20grid.pdfAccording to newly released scientific estimates, there is a roughly one-in-eight chance a massive solar storm will hit Earth by the end of the decade.
Analysts have been quietly studying the possible impact of this increasingly likely event for years. In 2013, the legendary insurance market Lloyd's of London estimated a Carrington-level storm, which occurs roughly every 150 years, would leave 20 to 40 million Americans without power from 16 days to two years.
The total economic cost for such a scenario is estimated at $600 billion to $2.6 trillion, Lloyd's claimed.