Duke Energy announced plans today to add up to 500 megawatts of utility-scalesolarin Florida by 2024. The solar expansion strategy was filed with the Florida Public Service Commission (FPSC) yesterday as part of Duke’s 2015 Ten-Year Site Plan.

"Innovative investments in solar energy will provide customers with more options to use this resource, while diversifying our energy mix and continuing to meet the needs of Florida's growing economy and population," said Alex Glenn, state president for Duke Energy Florida.

The 10-year plan also includes capacity upgrades at Duke’s Hines Energy Center to increase energy efficiency and power output during hot summer months; the addition of a combined-cycle natural gas facility in 2018 at Citrus County; a purchase and proposed acquisition of the Calpine Osprey Energy combined-cycle unit; and four planned combustion turbine units at an unspecified location in 2024.

Duke Energy Florida serves about 1.7 million customers with 9,000 megawatts of owned electricity capacity. Natural gas makes up more than 60 percent of Duke Energy Florida’s energy mix, and that amount will increase as the utility retires two coal plants -- which represent half of its coal fleet -- in the next three years.

Solar will also play an increasingly important role, said Duke spokesperson Sterling Ivey in an interview. The two retiring coal plants have a combined capacity of 869 megawatts, so adding 500 megawatts of utility-owned solar would go a long way toward replacing that fossil fuel generation, he said.

“If you look out across the 10-year landscape, adding 500 megawatts of solar is definitely going to be a significant resource for us,” said Ivey.

But while Duke has laid out an ambitious goal for 2024, the company’s only concrete plans are to build 5 megawatts of solar by the end of 2015. Another 35 megawatts of solar is expected to be completed by 2018. Getting to 500 megawatts of new solar capacity six years later would be a remarkably fast ramp-up.

Ivey said that Duke is deploying solar projects slowly in order to study how best to integrate the intermittent resource. The utility needs to find ways to store more solar energy, as well as to gain a better understanding of how smaller solar facilities, between 2 megawatts and 15 megawatts, interact with the electric grid.

Also, while the plan lays out modest near-term goals, it’s notable that among all of the utility resource plans announced to date, Duke’s calls for the most new solar to be brought on-line after the federal Investment Tax Credit drops from 30 percent to 10 percent at the end of 2016, said Cory Honeyman, senior solar analyst at GTM Research.

“To what extent those 500 megawatts will be realized is an open question,” said Honeyman. “But the fact that that’s a part of Duke’s resource plan is a really important validation of the potential long-term stability of the utility-scale segment, despite the stark drop-off expected in 2017.”

Relative to distributed energy, utility-scale solar is likely to be more sensitive to the ITC decline.

As Duke makes plans to add more solar in the Sunshine State, it’s also pushing to expand its solar footprint in other parts of the Southeast. Last year, Duke announced it would invest $500 million in 278 megawatts of utility-scale solar in North Carolina -- an unprecedented move in the state. Earlier this year, Duke proposed adding a total of 110 megawatts of solar power in South Carolina by 2021.

Over the past eight years, Duke Energy says it has invested more than $4 billion in wind and solar facilities in 12 states. The utility plans to invest another $2 billion to $3 billion in renewable energy over the next five years.

“Solar is going to be around,” said Duke's Ivey. “The cost is coming down, and we want to be able to use this resource to the best of our ability.”