The largest solar-electric generator in Minnesota has flipped on the switch -- the latest sign of a banner year for solar installations.

Renewable power developer Ecos Energy said 7,040 solar panels outside of Slayton, Minn., began producing power Friday after being connected to Xcel Energy's distribution system. The solar array is the largest in the state, with 2 megawatts of output, the equivalent of the power used by 250 homes.

The project has 32 rows of solar panels covering an area the size of 7 1/2 football fields on what once was a cornfield.

"There was no celebration, but it is nice to get these things running," said Chris Little, director of development for Ecos Energy, based in Minneapolis.

Solar installations are up dramatically in Minnesota and across the United States. In Minnesota, twice as much solar capacity was installed in 2012 compared with the prior year, as more than 250 projects, large and small, went online, state data shows.

That list doesn't include the Slayton project, which came online in 2013. It does include the solar array atop the Bloomington Ikea store completed in August. Ikea briefly held the state record for the biggest solar generator, at 1 megawatt, and now slips to No. 2.

Across the country, new solar installations through the third quarter already were ahead of 2011's, thanks partly to a steady drop in solar panel prices, according to a GTM Research report for the Solar Energy Industries Association.

"We expect business to grow considerably in 2013 and 2014," said Doug Fredrickson, vice president of operations for Blattner Energy, which constructed the Slayton project. "The indicators are really strong. The technology is improving, and the price of panels is going down -- you can hardly keep up with the reductions."

Blattner Energy, based in Avon, Minn., is a sister company to D.H. Blattner & Sons Inc., a contractor that helped James J. Hill build the Great Northern Railroad a century ago. It began building wind farms in the 1990s and utility-scale solar projects two years ago.

Lynn Hinkle, policy director for the Minnesota Solar Energy Industries Association, said the group is pushing for special, higher rates on solar power sold to utilities. The pricing aims to recognize that solar projects save utilities money by avoiding transmission-line investments and expensive power purchases on hot, sunny days, Hinkle said.

"That would help scale up the installation of solar," he said.

Ecos Energy deliberately sited its array near Buffalo Ridge in southwest Minnesota, an area with more than 70 wind farms. Xcel, the Minneapolis-based utility, intends to study whether daytime-only solar power and nearby wind farms' intermittent generation can complement each other. Wind often is strongest at night. Xcel spokeswoman Patti Nystuen said that a year's worth of data will be needed to conduct the analysis.

Xcel will purchase the power under a 20-year agreement whose terms have not been disclosed. Regulatory filings say the Slayton project cost about $7 million, with $2 million from Xcel's Renewable Development Fund. The state-mandated fund gets its money from utility ratepayers.

Ecos Energy built eight solar projects in the Midwest last year, including Slayton, Little said.

The company is majority owned by New York City-based Allco Renewable Energy. Ecos formerly was called Outland Renewable Energy and had been a sister company of Canby, Minn.-based Outland Energy Services, which was founded by Minnesota farmers to operate wind farms. Outland Energy was acquired in November by Duke Energy of Charlotte, N.C.

Though the Slayton project is Minnesota's largest, its output pales in comparison with solar installations being built in California. Last week, MidAmerican Solar, a unit of Warren Buffett-led Berkshire Hathaway, announced it would purchase the world's largest planned solar development, with an output of 579 megawatts, in southern California. NextEra Energy is planning a 250-megawatt concentrated solar project near Blythe, Calif., for which Blattner Energy is the construction manager.

In Minnesota, Xcel's separate Solar Rewards program helped installers add 3.7 megawatts of solar power this year, up 150 percent from 2011, the utility said. That program subsidizes smaller installations for homes and businesses.

Nystuen said Xcel will continue to "explore the potential benefits of solar" and anticipates requesting proposals for development fund grants for systems of up to 1 megawatt. Those projects, she said, likely would not involve selling power to the grid.

David Shaffer • 612-673-7090 Twitter: @ShafferStrib