The U.S. International Trade Commission voted on Friday to proceed with an investigation into whether solar panels from India, Laos and Indonesia are stifling domestic manufacturing, a key procedural step that could result in tariffs on those imports.

The unanimous decision by the three-member panel is a victory for domestic solar manufacturers who say Chinese companies with operations in those countries receive unfair government subsidies and are selling their products below the cost of production in the United States. U.S. producers are seeking to protect billions of dollars of investment in American factories.

"Today's ITC decision confirms what our petitions allege: U.S. solar manufacturers are being undercut and harmed by unfairly traded imports. Chinese-owned and other companies in Laos, Indonesia, and India are gaming the system with unfair practices that are gutting U.S. jobs and investment," said Tim Brightbill, lead counsel to the Alliance for American Solar Manufacturing and Trade and partner at Wiley Rein LLP.

The case was brought in July by the alliance, a coalition of U.S. solar manufacturers including First Solar and Hanwha's Qcells.

Imports from India, Indonesia, and Laos surged to $1.6 billion last year, up from $289 million in 2022, according to the group. Many of these imports are believed to have shifted from countries already subject to U.S. tariffs on Southeast Asian solar exports.

The U.S. Department of Commerce will continue investigations into the imports, with preliminary determinations on countervailing, or anti-subsidy, duties expected around Oct. 10 and on antidumping duties around Dec. 24.