The U.S. Department of Energy says solar panels assembled in Mountain Iron, Minn., are among the most reliable in America, the Duluth News Tribune reports.

Tests by National Renewable Energy Laboratory in Colorado showed the panels built by Silicon Energy were the most durable when it comes to high humidity and temperature extremes.

“The panels we make in Minnesota went up against five of the world’s biggest and best, and we beat them all,” Gary Shaver, Silicon Energy president, told the newspaper.

Silicon Energy missed its first two repayments last year on a $1.5 million government loan after selling fewer panels than expected. The loan has since been restructured and comes due starting in September, according to the Duluth News Tribune.