It's no secret that the sun has been acting rather strange lately, and it's very difficult to predict what it will do next. Although the likelihood of a devastating solar flare is low, damage to our infrastructure by solar activity has happened in the past and it will happen again.
In 1859 a huge solar storm burned out telegraph wires across Europe and the United States. Dr Stuart Clark has written a book, The Sun Kings, about when that happened. He says that the “Carrington flare”, as it was known, “smothered two-thirds of the Earth’s skies in a blood-red aurora a night later, and crippled all of global navigation and global communication, such as it was at that time. Compasses span uselessly and the telegraph network went down as phantom electricity surged through the wire.”
The sun's 11-year peak -- or "solar maximum" -- is due in 2013. The last one in 2001 did one billion dollars [USD] infrastructure damage.