SACRAMENTO, Calif. — Power-hungry TVs will be banned from store shelves in California after state regulators Wednesday adopted a first-in-the-nation mandate to reduce electricity demand. On a unanimous vote, the California Energy Commission required all new televisions up to 58 inches to be more energy efficient, beginning in 2011. The requirement will be tougher in 2013, with only a quarter of all TVs currently on the market meeting that standard. The commission estimates that TVs account for about 10 percent of a home’s electricity use. The concern is that the energy draw will rise by as much as 8 percent a year as consumers buy larger televisions, add more to their homes and watch them longer. Commissioners say energy efficiency standards are the cheapest and easiest way to save electricity. ‘‘We have every confidence this industry will be able to meet the rule and then some,’’ Energy Commissioner Julia Levin sai.