The utility -- a subsidiary of North Carolina based Duke Energy -- filed the rate request Friday. Duke has 1.7 million customers in the state including residents of St. Petersburg and Clearwater.
The rate hike is being blamed primarily to higher costs for natural gas and coal which are passed on to consumers.
But the overall hike also includes a previously announced charge related to Duke's nuclear power plants. Company officials noted other charges that are part of customer bill will go down.
The Florida Public Service Commission will review the rate hike in November.
If approved the rate hike would raise the monthly bill of an average customer by about $8.24 starting in January.