We use electricity. Lots of it!
On March 13, 1989, an electrical power blackout caused by a severe solar storm struck Quebec. It lasted 12 hours and affected 5 million people at an eventual cost of over $2 billion. Although electrical outages are very common, and we have all experience them, the ones caused by solar storms are very different. They can potentially cover entire continents because they are a global phenomenon.
The estimated cost for a storm like the one that happened on May 15, 1921 is about $26 billion per day, affecting about 150 million people.