DUBUQUE — Alliant Energy Spokesman Justin Foss walked along more than 21 acres of rolling terrain just west of Dubuque.

Once farmland in the city’s industrial sector, the area on Monday was blanketed by rows of metal posts that soon will become the foundation for more than 15,600 solar panels.

“This will be the largest single solar site in the state,” Foss said.

Crews, earlier this year, began work on the $10 million project that will transform the 21.1 acres of land into the utility’s first large-scale solar project in Iowa.

Foss said the 5-megawatt array, which represents Alliant’s first large scale solar project in the state, is expected to go online in August and will produce nearly 6.6 million kilowatt-hours of power annually, or enough to power about 727 homes a year.

The project, a collaboration between Alliant, the city of Dubuque and the Greater Dubuque Development Corp., is located in Dubuque’s Industrial Center West — an area that provides a natural south-facing slope.

That terrain allows Alliant to place solar panels closer together than they normally would on flat ground and get more energy per acre, Foss said.

Not far from the industrial park project, near downtown Dubuque, Alliant is working with A.Y. McDonald Manufacturing on a second solar project — a more than 3,500-panel, 1.2-megawatt system. The array will generate enough energy to power 126 homes when the project goes online in September.

In addition, the downtown array will include an educational component for visitors.

Foss said it was the declining cost of solar projects that helped bring the two Dubuque projects to fruition.

“The cost of solar has come down so it is a good time to start building it large scale, so that we can utilize the lessons that we’ve learned in past installations, apply them to this and use this to develop solar in the state,” Foss said.

Much of the solar power on Alliant’s grid is generated by residential or commercial units — the utility has more than 2,100 customer-owned solar systems in the state. But Foss said the utility could pursue more large-scale projects like those being added in Dubuque.

“We’re actively working on other sites and projects,” he said.

In 2014, Iowa’s cumulative solar installations made up about 20 megawatts of generation compared to nearly 6,000 megawatts of wind power statewide, according to Iowa Environmental Council data. The industry was projected to be at about 60 megawatts last year.

But while solar has seen some growth in Iowa in recent years, wind power has reached close to 7,000 megawatts — surpassing one-third of the state’s total energy production. By 2020, wind production should surpass 9,000 megawatts.

Last fall, Alliant announced a $1 billion, roughly 500-megawatt investment in wind power.

“Our strategy is to move to cleaner energy, but we also want to do it in a way that maintains reliability and affordable energy,” Foss said.

Meanwhile MidAmerican Energy last year announced a $3.6 billion, 2,000-megawatt proposal, dubbed Wind XI.

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