A judge for the U.S. Court of International Trade on Nov. 16 set aside a proclamation issued by former U.S. President Donald Trump that revoked an import tariff exclusion for bifacial solar modules, thereby creating a potentially valuable new source equipment for solar project developers stung by recent market upheaval.

Judge Gary Katzmann wrote in an opinion that Trump's proclamation "constituted an action outside the President's delegated authority" because the executive branch is not empowered by the Trade Act of 1974 to make "trade-restricting modifications" to existing tariffs.

In addition to upholding the tariff exclusion for bifacial solar modules, Katzmann's order struck down a decision by the Trump administration to ease duty rates on solar imports more gradually than it had initially planned.

"The decision by the U.S. Court of International Trade to strike down an order by President Trump to change the step-down rate for the Section 201 tariffs and reverse the bifacial module exclusion was clearly the right conclusion," Abigail Ross Hopper, president and CEO for the Solar Energy Industries Association, which is a plaintiff in the case, said in a statement.

"Both actions were an unlawful attempt to harshen the Section 201 tariffs," Hopper said, referring to the section of the Trade Act of 1974 under which Trump issued the tariffs.

The U.S. Justice Department, which argued to uphold Trump's proclamation, declined to comment.

Katzmann's ruling was the latest twist in the yearslong saga. After Trump issued safeguard tariffs on most imported solar cells and panels in 2018, the Office of the U.S. Trade Representative said bifacial panels, which can absorb sunlight on both their front and back, would not be subject to the duties. The Trump administration later reversed that decision, saying the exclusion would undercut efforts to shield domestic manufacturers from foreign competition.

Now, project developers can once again avoid Trump's solar tariffs by purchasing bifacial modules, which are used in large utility-scale projects. That is particularly welcome news in light of a run-up in modules prices in 2021 due to rising raw material costs.

With many modules orders for 2022 already locked, "this likely doesn't change most of the current deals, but it does make it less painful overall," analysts at ROTH Capital Partners LLC said in a note to clients Nov. 16.