Solar power in Minnesota just got its biggest jolt ever.

State utility regulators on Thursday unanimously directed Xcel Energy to go ahead with three large solar projects that will mean a tenfold increase in the amount of electricity generated from the sun in Minnesota.

The projects near the cities of Marshall, North Branch and Tracy each are expected to be completed in 2016 to qualify for an expiring 30 percent federal solar power tax credit.

The state Public Utilities Commission considered whether to approve all of the projects after Xcel said it needed only two to meet a state mandate that investor-owned utilities get 1.5 percent of their electricity from solar by 2020.

Commissioner John Tuma, who was appointed to the PUC this month, said that building all three projects made sense, partly because there is no guarantee that the federal tax credit will be reauthorized. He said it also sends a signal to energy developers that Minnesota is moving toward more solar power.

“We’ve got a 30 percent off sale here today,” Tuma said, referring to the tax benefit that expires at the end of 2016. “I don’t know if that is going to be here in a year. We know it is here today.”

Clean energy advocate Kevin Reuther applauded the decision.

“This is a great first step,” Reuther, legal director of the Minnesota Center for Environmental Advocacy, a nonprofit St. Paul law firm, said the 187 megawatts of solar power is roughly the equivalent to that used by 41,000 homes.

“In terms of the overall megawatts it’s little,” he added. “In terms of sending a signal to the consumer and the industry, it’s big.”

The largest of the projects is a 100-megawatt solar array planned southeast of North Branch, Minn., by Community Energy, a wind and solar energy developer based in Radnor, Pa.

That project, called North Star Solar, would be, by far, the largest single solar park in the state, covering 1.25 square miles. Its output would be 50 times greater than the state’s biggest solar generator, a 2-megawatt array completed two years ago in Slayton, Minn. A megawatt is 1 million watts.

The other two projects also are large, and will feature panels that track the movement of the sun from east to west, allowing them to capture more energy late in the afternoon, when summer power demand can spike.

NextEra Energy, the renewable energy affiliate of Florida Power & Light Co., plans to build a 62-megawatt solar project covering 464 acres east of Marshall, Minn. Juwi, a worldwide renewable energy company based in Worrstadt, Germany, proposes the 25-megawatt MN Solar I project north of Tracy, 160 miles southwest of the Twin Cities.

Aakash Chandarana, director of regulatory affairs at Xcel, said it was a “close call” on whether to build two or three solar parks. He said going ahead with all of the projects is cost-effective when the reduction in pollution and carbon dioxide emissions from fossil-fuel plants are considered. He said the power would cost about 7.5 cents to 8.5 cents per kilowatt hour.

Xcel, which serves 1.2 million electric customers in Minnesota, would not own the projects, but has agreed to purchase the electricity under long-term contracts. The projects still require various permits to go ahead.