A group of solar manufacturers is seeking retroactive duties on imported panels and cells, as the federal government probes whether the goods are being dumped in the US at below-market prices.

The companies, in a filing disclosed Thursday, have asked the Commerce Department to apply the duties right away, amid a surge in imports from Vietnam and Thailand. An existing trade case already poses the risk of anti-dumping and countervailing duties, but the new filing raises the prospect of duties being imposed even before a final decision in the case. 

If imports have surged during a trade investigation, the government can determine that “critical circumstances” exist — a finding that paves the way for such retroactive tariffs. Companies importing panels and cells would need to post cash deposits while awaiting a final decision in the trade case. 

The manufacturers cited a 39% increase in imports from Vietnam and a 17% increase from Thailand between April and June 2024, when compared to January through March 2024. Tim Brightbill, partner at Wiley Rein and lead counsel to the petitioners, said China-based companies operating in those countries appeared to accelerate exports after the trade case was filed earlier this year.

The Biden administration has made nurturing a domestic solar supply chain a high priority. Although tax incentives under the Inflation Reduction Act are driving investments in new US panel- and cell-making factories, some manufacturers argue tariffs are needed to counter a wave of cheap imports undermining those plans. A group of companies united as the American Alliance for Solar Manufacturing Trade Committee pushed for the current trade investigation, saying foreign panels were being unfairly subsidized and sold in the US below cost. 

Companies pursuing the claims as part of the trade committee include Convalt Energy Inc., First Solar Inc., Hanwha Q Cells USA Corp., and Mission Solar Energy LLC.