The vast expanse on the east side of Bartow once represented an extractive industry of the early 20th century: phosphate mining.
The tract just north of State Road 60 served as a clay settling area, an impoundment holding water that allows dirt and clay to settle.
The 422-acre property — covering roughly the area of 30 professional football stadiums — has been transformed into a symbol of clean, 21st century energy. Countless rows of gleaming, black solar panels stand like sentries ready to track the sun each day, absorbing light and converting it into enough energy to power 8,500 homes.
The Peace Creek solar facility, part of Tampa Electric’s plans for a 10-site project, is complete and ready to begin operating soon.
Mark Ward, director of renewables for TECO, strode between the rows of solar panels on a recent morning, explaining the technology that is allowing the company to rely less on coal and natural gas in energy production.
“Once we get this up and going in another month, month and a half, you come out here and you’ll only hear the birds singing,” Ward said.
Five of TECO’s current or planned solar sites are in Polk County. The Bonnie Mine plant, southeast of Mulberry, and the Payne Creek plant, near the county’s southern boundary, are both operating.
Less than 10 miles west of the Peace Creek site, construction continues on the Lake Hancock facility, a 356-acre project on the west side of U.S. 98 a few miles north of Bartow. Four more solar farms are either complete or planned in Hillsborough County, and another is scheduled for construction in Pasco County.
TECO officials say the company will have added 6 million solar panels through the projects by 2021, enough to power more than 100,000 homes. At that point, solar sites will generate nearly 7 percent of TECO’s energy production, the company says.
TECO, which has about 84,000 customers in Polk County, operates a gas-powered plant in the Palm River area, a coal-fired plant near Apollo Beach and a gasified coal plant near Brewster in southern Polk County.
Lakeland Electric, which serves about 128,000 customers, has five solar farms totaling about 88 acres, spokesman Chris Neal said.
The Peace Creek site was part of the Clear Springs mine first excavated by the Virginia Carolina Chemical Co. in 1950, said Gary Albarelli of the Florida Industrial and Phosphate Research Institute at Florida Polytechnic University. IMC Corp. took ownership in 1969 and mined the site intermittently until 1999, Albarelli said.
Construction began last September, led by First Solar, an Arizona-based company that also manufactures solar panels. The site had as many as 745 employees working at the peak of construction, including security staff and other subcontractors, said Bill Salmon, TECO’s construction superintendent.
The property’s history is still apparent in the gooey dirt that clings to the soles of shoes. The site design includes drainage pockets free of solar arrays.
Overall, though, the tract occupies relatively high ground, Salmon said.
“This is a great site,” Salmon said. “It’s elevated, and we like that. It’s pretty uniform. We like high and dry (land). It’s hard to find in Hillsborough, Polk and Pasco.”
A high point near the property’s western edge yields a view of the sea of solar panels. With the morning sun shining on the sleek panels, blotches of color appear as rainbow reflections on some of them.
Acres of glass
The Peace Creek site contains about 545,000 panels, Salmon said, and each panel generates about 70 volts of power. The facility has its own substation, which sends 69-kilovolt currents out through electrical lines that head toward a distribution substation in the Winter Haven area.
The solar facility will generate peak production of 55.5 megawatts of power, Ward said. Coal- and gas-powered plants produce more energy and do so throughout the day, while solar facilities generate electricity only during daylight.
As solar panels absorb sunlight, the cells receive photons, or light particles, dislodging electrons from their atoms. The panels contain silicon or other materials and act much like semiconductors used in computers. Positive and negative layers create an electric field, and the conduction forms an electrical circuit.
Electrons flowing through the electrical circuit generate energy, and panels are wired together to feed that direct current (DC) electricity to inverters that transform it into the alternating current (AC) power that goes to houses and businesses.
Up close, the solar panels look almost like works of art, their shiny, black surfaces showing a series of thin, vertical lines, the channels through which the electrons flow. Each panel — roughly 2 feet tall and 4 feet wide — consists of two thin plates of glass pressed tightly together.
The panels at Peace Creek use cadmium telluride, rather than crystalline silicon, the material used in first-generation panels, in their conductive layer, Salmon said.
Manufacturers favor dark panels over the reflective surfaces of the industry’s early years in part because they don’t create glare that causes birds to mistake the surfaces for water and fly into them, TECO spokeswoman Cherie Jacobs said.
Panels are arranged in stacks of three separated by gaps about an inch wide. The modules form blocks held up by thick, metal posts — about 40,000 of them — driven into the ground by machines originally designed to plant posts for highway guardrails.
White boxes set among the rows of panels contain the motors that drive the rotation of the arrays. Each motor has its own small solar panel to charge its batteries.
The solar farm is divided into two blocks separated by a road wide enough to accommodate large trucks. The rows of panels, placed about 12 feet apart, stretch for as much as 500 feet on either side of the road.
Once the facility goes online, a control system will turn the panels into high-tech sunflowers that rotate imperceptibly throughout the day to keep their surfaces directed toward the sun. The movement will be programmed based on scientific data, meaning the slow-motion tilt will occur even on cloudy days.
The network of panels is designed to withstand hurricane winds, Salmon said. Drawing from weather stations on site, a computer system will rotate the panels to a position slightly off horizontal in the event of high winds that prevents the danger of strong gusts lifting the panels from below.
The site contains 18 solar inverter units that form what Ward called “the whole brains of the system.” One of them, a whitish block of metal about the size of a long horse trailer, sat on a platform at the edge of the center road.
Each unit contains six computer-controlled inverters, which receive feeds of 1,500 volts of DC power from each solar panel array and convert it to 34.5 kilovolts of AC electricity. The inverters send that power into a transformer built into the unit, and from there it travels through lines to the substation.
A solar facility filled with metal structures is a virtual magnet for lightning, and Ward pointed out the extensive grounding system designed to prevent strikes from causing damage. Solar panel arrays and their posts have their own grounding systems, and copper cables tie the entire grounding network together.
The inverter units have their own lightning protection, Ward said, and the substation contains several metal towers topped by lightning rods.
Ward says the Peace Creek site will produce enough electricity to supply 8,500 homes, but that power won’t go to individual customers. Like traditional power plants, TECO’s solar farms transmit electricity to the company’s local network — the grid — and it essentially blends with the power produced by other facilities.
Even in the late stages of construction, the Peace Creek site thrummed with activity Wednesday morning. When the plant becomes active, though, Ward said it will run mostly on its own, requiring workers only for occasional maintenance.
Ward said infrared cameras will monitor the arrays for any hot spots that develop. The site will also have a network of security cameras.
By contrast, a coal-fired power plant generally has about 200 employees working, Jacobs said, while a gas-fired plant demands a crew of 50 to 60.
A 6-foot-tall fence rings the field of solar panels, topped by a fringe of barbed wire angled outward. Salmon said TECO also installs a horizontal strip of metal wire to prevent wildlife — particularly foxes, raccoons and coyotes — from digging under the fence and causing damage.
One category of animals, though, will be not merely allowed but actually invited onto the property. Having crews operate lawn mowers amid the solar arrays would be potentially dangerous for the workers and would risk damage to the panels, so TECO instead rents sheep to maintain the grass in its solar farms.
“Unless we have some preventive or actual maintenance,” Ward said, “there will be nobody on these sites except for the sheep.”
Salmon, who has worked in or helped construct traditional power plants, said it’s “refreshing” to see a solar farm being built. He listed the benefits: solar panels require no fuel, don’t generate pollution and have low operation and maintenance costs.
“It’s good for everybody,” he said. “It’s good for the environment. It’s good for customers. It’s good for TECO.”
Winter Haven resident John Ryan, a longtime environmental advocate and former energy chairman for the Sierra Club’s Florida Chapter, said solar power isn’t perfect but is preferable to power plants that burn fossil fuels. He said he has been advocating for solar power since 1998.
“Certainly the cost of solar, especially on the utility scale, has gone down substantially and they actually compete in cost better with fossil-fuel power plants,” Ryan said, “so from both an economic point of view and an environmental point of view, including (concerns about) climate change, it’s definitely a positive.”
Ryan said some residents object to the site of a solar farm near their homes, but he said such concerns are offset by the many positives of solar power. Solar facilities don’t burn fossil fuels and don’t generate pollutants that can harm health or greenhouse gases that contribute to climate change, he said.
The main disadvantage of solar energy at this point, Ryan said, is the lack of an efficient way to store the power the panels generate. That means surplus power is lost.
Ryan said the lack of paved areas at solar facilities means rainfall is absorbed by the ground and recharges the Floridan Aquifer, the state’s main source of drinking water.
“The long-term benefits of producing more solar, even if there is fossil fuel (power) in the grid, is it reduces the overall cost to the user and to the utility and eventually, when we get storage, solar may be one of the principal forms of power generation,” Ryan said.