[SMM Analysis]TOPCon Section 337 Investigation June Update: Tesla and BYD America Granted Intervention

Figure 1: Key Timeline of the TOPCon Section 337 Investigation

In June 2026, there were new procedural developments in the U.S. Section 337 investigation initiated by First Solar against TOPCon photovoltaic products. The investigation was formally instituted by the U.S. International Trade Commission (ITC) in March under Investigation No. 337-TA-1494. The products under investigation include certain TOPCon solar cells, modules, panels, and related products. First Solar alleges that certain imported products infringe its U.S. patent rights and has requested that the ITC issue exclusion orders and cease-and-desist orders.

The case is still at the procedural stage and has not yet reached a final infringement ruling. However, several developments in June have attracted market attention.

In early June, BYD America was granted permission to intervene in the case. Tesla was later also granted intervention. According to public filings, Tesla filed its motion to intervene in late April. First Solar did not oppose the motion, and the ITC’s investigative staff also supported Tesla’s intervention.The participation of these two parties has broadened the market’s attention around the case. Previously, the market mainly focused on the listed photovoltaic manufacturers and whether the relevant TOPCon products could be affected. Following the intervention of Tesla and BYD America, market discussion has increasingly turned to potential supply chain risks for downstream companies in the United States.For U.S. project-side companies, the potential impact of the Section 337 investigation may involve module procurement, project delivery, inventory sales, and future supplier selection. If the final outcome affects the ability of certain TOPCon products to enter the U.S. market, downstream companies may need to adjust procurement plans in advance or include more detailed intellectual property and trade compliance clauses in contracts.

On June 24, the ITC terminated the investigation as to Mundra Solar Energy Ltd. and Adani Green Energy Ltd., following First Solar’s withdrawal of its complaint against these two companies. Based on public information, this was a voluntary withdrawal by First Solar against the two Indian companies and does not mean that the ITC has made a substantive determination on whether the two companies infringed any patents.On June 25, the ITC confirmed the correction of the respondent name from JA Solar AZ, LLC to American Panel Solutions LLC. This was a legal-entity name correction and was mainly intended to further clarify the parties involved in the investigation.

These adjustments indicate that the case is gradually clarifying the parties involved and the scope of the investigation. Going forward, the market still needs to monitor the remaining respondents, the scope of the relevant products, and the ITC’s substantive proceedings.

Figure 2: Technical Illustration of TOPCon Solar Cells/Modules

Market Focus: Will U.S. Customers Become More Cautious?For Chinese photovoltaic companies, the key impact of this case lies in the increased uncertainty surrounding the U.S. market. In the past, companies exporting to the United States mainly focused on tariffs, country of origin, anti-circumvention rules, and supply chain traceability. The TOPCon Section 337 investigation has brought patent risk into sharper focus.

If the case continues to move forward, U.S. customers may pay closer attention to patent licensing, product origin, contractual liability allocation, and alternative supply arrangements when selecting TOPCon modules. For companies planning to enter or remain in the U.S. market, freedom-to-operate reviews, customer contract terms, and overseas legal response capabilities may become increasingly important.

Figure 3: U.S. Solar Manufacturing or Utility-Scale Solar Farm Image

At this stage, the June updates remain procedural, and the final outcome of the case is still unclear. However, after Tesla and BYD America were granted intervention, the investigation is no longer only a patent dispute among manufacturing-side companies. It has also started to affect how U.S. downstream customers assess supply chain stability.Going forward, three issues deserve close attention: first, whether the ITC will make substantive determinations on infringement and patent validity; second, whether the case will affect the export of certain TOPCon products to the U.S. market; and third, whether U.S. downstream customers will adjust their procurement strategies and contract requirements.