Of course, many energy companies and some conservative lawmakers are skeptical about batteries. They argue that it would be far better to build and maintain natural gas power plants because utilities have decades of experience with them and gas is abundant and relatively cheap. Batteries, they argue, are expensive and can only provide electricity for short stretches — typically four or five hours.
Dominion Energy, one of the nation’s largest utilities, for example, is investing in batteries but has also argued that natural gas power plants are critical to ensuring a reliable grid. “Our view is that it cannot be an either-or decision,” Katharine Bond, a Dominion vice president, said in a recent interview.
But both proponents and critics of batteries agree that such devices, along with renewable energy, pose a fundamental challenge to an electricity system that has long worked in a top-down way. Historically, utilities built power plants and strung lines to deliver electricity to homes and businesses. That model was stable for decades and it earned utilities a guaranteed rate of return on their investments, typically 10.5 percent.
But homes and businesses are increasingly not just users of electricity. As the cost of solar panels and batteries has plunged in recent years, people can generate their own power and become suppliers, too.
Sunrun, the nation’s largest residential solar company, said about 20 percent of the solar power systems it installs include batteries, up from 10 percent just a year ago. In the Bay Area, 60 percent of installations include batteries.
Lynn Jurich, Sunrun’s chief executive, asserts that the batteries her company installs — it has about 5,000 across California — should be treated like a virtual power plant that can be turned on and off much faster than a plant fueled by fossil fuels. And Sunrun’s virtual power plant can just as easily absorb power when there is too much supply.