Florida Power & Light plans to build the world's largest solar-powered battery system and it will be charged by an existing solar power plant in Manatee County. When completed, the company's Manatee Energy Storage Center will have 409 megawatts of capacity, the equivalent of approximately 100 million iPhone batteries. It will begin serving customers in late 2021. The Energy Storage Center is part of a broader modernization plan developed to accelerate the retirement of two, 1970s-era natural gas generating units at Florida Power & Light's neighboring power plant and replace them with clean, renewable energy.