US patent office upholds First Solar's patents against third-party challenges

JinkoSolar Holding

20/01/2026 14:12

Jan 20 (Reuters) - First Solar FSLR.O said on Tuesday the United States Patent and Trademark Office director denied three separate third-party applications challenging the validity of its solar cell technology patents.

The applications seeking to invalidate First Solar's tunnel oxide passivated contact (TOPCon) technology were filed by JinkoSolar JKS.N, Mundra Solar and Canadian Solar CSIQ.O in 2025, and were rejected on November 20, December 11, and December 18, respectively.

First Solar has pending lawsuits against all three companies alleging infringement of its patents in the United States District Court for the District of Delaware.

JinkoSolar, Mundra Solar and Canadian Solar did not immediately respond to Reuters requests for comment.

TOPCon has been overtaking rival solar cell technology, crystalline silicon, due to its higher efficiency in converting sunlight into electricity.

First Solar said it obtained the U.S. TOPCon patents and related international counterparts through its 2013 acquisition of TetraSun.

 (Reporting by Pranav  Mathur in Bengaluru; Editing by Vijay Kishore)

 ((Pranav.Mathur@thomsonreuters.com;))