The US International Trade Commission (ITC) has opened a Section 337 investigation into tunnel oxide passivated contact (TOPCon) solar cells, modules, panels, and related products following a complaint by First Solar, naming 47 entities across 11 countries as respondents.
ITC building in New York
Image: Toytoy, Wikimedia Commons, https://bit.ly/3jG7CHs
The US ITC has opened a Section 337 investigation into certain TOPCon solar cells, modules, panels, components, and products containing them, in a case that could raise fresh uncertainty for TOPCon players serving the United States.
The investigation, listed as 337-TA-1494, follows a complaint filed on Feb. 24, 2026, by First Solar, and supplemented on March 10. The company alleges infringement of claims 1, 2, 4, and 8 of US Patent No. 9,130,074, and has asked the ITC to issue a general exclusion order, or alternatively a limited exclusion order, as well as cease and desist orders.
The ITC voted on March 25 to institute the investigation, with the formal notice issued on March 26. The case will examine whether imports, sales for importation, or sales after importation into the US violate Section 337, and whether a domestic industry exists or is being established around the asserted patent.
The respondent list is broad, covering 47 entities across 11 countries. It includes major solar manufacturers and related entities tied to Canadian Solar, JA Solar, JinkoSolar, Runergy, Trina Solar, Hanwha Qcells, Adani-linked Mundra Solar entities, AXITEC, Philadelphia Solar, VSUN, Toyo, and T1 Energy, spanning operations in China, the United States, Canada, Germany, Vietnam, Malaysia, Thailand, India, Jordan, South Korea, Japan, and Hong Kong.
What makes the case especially significant is the remedy sought. Unlike anti-dumping or countervailing-duty cases, a Section 337 investigation centers on intellectual property. If the ITC ultimately issues a general exclusion order, the effect could extend beyond named respondents, potentially blocking products found to use the disputed TOPCon technology from entering the US market.
That matters because TOPCon has become the dominant n-type solar cell technology in China and a major export platform for global module supply. The complaint therefore represents a significant threat for manufacturers that have relied on TOPCon as their main technology for international markets, including the US.
The procedural timeline is now critical. The ITC notice says respondents must submit responses within 20 days after service of the complaint and notice, and warns that failure to respond in time could lead to default findings and the issuance of exclusion or cease and desist orders.
For the solar market, the case is now more than a patent dispute. It has become a test of whether TOPCon’s global scale can withstand a major intellectual property challenge in one of the industry’s most politically and commercially sensitive markets.
In January, the US Patent and Trademark Office denied three separate review applications – from JinkoSolar, Canadian Solar, and Mundra Solar — seeking to invalidate patents related to TOPCon technology held by First Solar, leaving the patents intact as First Solar pursues infringement litigation in the US District Court for the District of Delaware.
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