A solar disaster isn't a question of if, but when--and it looks like soon
One of the biggest disasters we face would begin about 18 hours after the sun spit out a 10-billion-ton ball of plasma--something it has done before and is sure to do again. When the ball, a charged cloud of particles called a coronal mass ejection (CME), struck the Earth, electrical currents would spike through the power grid. Transformers would be destroyed. Lights would go out. Food would spoil and--since the entire transportation system would also be shut down--go unrestocked.
Read more http://www.popsci.com/science/article/2011-05/are-we-prepared-catastrophic-solar-storm