In an unprecedented decision, a Minnesota judge this week held that utility supplier Xcel Energy should invest in the solar energy developer Geronimo Energy rather than in natural gas generators because that choice is the better economical and environmental deal for the state.

Judge Eric Lipman's ruling must be approved by the Minnesota Public Utilities Commission, which initially ordered the proceeding to force energy companies to compete on price. The commission is expected to issue its final ruling in March.

Lipman said in the 50-page ruling, issued Tuesday, that the Geronimo project "will have numerous socioeconomic benefits, minimal impacts on the environment and best supports Minnesota's efforts to reduce greenhouse gases." 

The decision, if approved, would help Xcel fulfill its requirement to attain 1.5 percent of its power from the sun by 2020 under a new state energy law.

Geronimo Vice President Betsy Engelking said the decision marks a turning point for the solar industry because it is the first time that unsubsidized solar energy has gone head-to-head with natural gas resources and been selected as the best option.

"The judge decided that it was the best option for economic and environment reasons," Engelking told Al Jazeera. "Economically, the judge found that it was the lowest cost option offered."

If the decision stands, Geronimo plans to build roughly 20 solar arrays at a cost of $250 million.