Summer is blackout season, when heat waves bring on extra air-conditioning use, and extra air-conditioning use taxes the power grid and leads to rolling blackouts. And while the power grid in the U.S. is relatively stable—99.9 percent stable if you factor out weather-related outages, according to the Electric Power Research Institute—power outages are a year-round fact of life.

A growing population, along with more homes that cover more area, has meant that hurricanes, wildfires, and other disasters impact more people and have led to a staggering increase in power outages. According to Dr. Massoud Amin, a professor of electrical and computer engineering at the University of Minnesota, 500,000 people per day in the U.S. lose power for at least two hours. Between 2005 and 2010 there were 272 power outages that each affected more than 50,000 people.