A Florida utility has unveiled what it says is the world’s largest solar-powered battery storage system, Kallanish reports.

The announcement came from Florida Power & Light in a night-time ceremony with lights and drones powered by the battery earlier this week at the Manatee Solar Energy Center in Florida’s Manatee County.

The $300 million battery has a 409-megawatt capacity and can deliver 900 megawatt-hours of energy, the equivalent of 100m iPhone batteries or enough energy to power about 329,000 homes for more than two hours, says the company, a subsidiary of NextEra Energy. That is also enough energy to power Disney World for seven hours, it says. The project will help increase the predictability of solar, the company says.

The project includes 132 battery containers on 40 acres, equivalent to 30 football fields. It sits next to the existing 74.5 MW Manatee solar facility. Electricity will be stored in the batteries when the sun is shining and power is cheaper due to low demand. That power will be added to the grid when demand peaks and power is more expensive. It will reduce the runtime of local fossil-fueled power plants, reduce carbon emissions and help the company to retire two aging natural gas-fired peaking power plants that together produce 1.638 gigawatts of power.

The company had previously said the battery project would save its customers about $100m over its lifetime by offsetting fuel costs.

“This battery is another example of how FPL has become a leader in clean energy and sustainability without sacrificing affordability or reliability,” says president and ceo Eric Silagy in a statement.

Construction started last February on the battery system in Parrish, Florida.

The utility with 11m customers in Florida says it has installed 13m solar panels and is 45% of the way to reaching its goal of installing 30m solar panels across the state by 2030. It operates 42 solar facilities with eight more expected to come online in early 2022. The company is adding other smaller battery projects in the state.