Officials and experts said the grid is better equipped now than it was last August to handle a hot-weather surge in electricity demand. Last August, for the first time since 2001, residents endured rotating power outages because of the heat (wildfire risk has separately prompted power companies to cut electricity to prevent power lines felled by strong winds from starting new blazes). But California’s system still could face electricity shortfalls if the region is scorched again this summer. The California ISO’s “flex alert” asks residents to voluntarily cut back on their electricity use between 5 p.m. and 10 p.m., when demand peaks. During those hours, people come home from work or school, fire up their air conditioners and switch on appliances, increasing the load on the grid. As the sun sets, electricity flowing from solar energy sources diminishes, meaning there’s less power to go around. At the same time, temperatures outside remain high well into the evening and structures retain the heat they’ve absorbed during the day, pushing air-conditioning loads higher.