US patent office validates First Solar’s TOPCon intellectual property

First Solar revealed that the United States Patent and Trademark Office (USPTO) has denied three separate inter partes review (IPR) applications seeking to invalidate its TOPCon patents. The IPRs were filed by JinkoSolar, Mundra Solar and Canadian Solar, and all three were denied before the end of 2025.

First Solar, a cadmium-telluride thin-film manufacturer, has TOPCon patents through its acquisition of TetraSun in 2013. Prior to its acquisition, the California-based startup had developed proprietary cell architecture and manufacturing processes for large-format crystalline silicon wafers.

While JinkoSolar and Canadian Solar sought to invalidate First Solar’s U.S. Patent No. 9,130,074, Mundra Solar’s application sought a review of First Solar’s US Patent No. 9,666,732. Both patents cover methods of manufacturing TOPCon crystalline silicon solar cells. 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.

“First Solar believes the USPTO properly exercised its discretion in each of the cases brought by Jinko, Canadian Solar and Mundra,” said Jason Dymbort, executive VP, general counsel and secretary of First Solar. “We believe that this is consistent with USPTO’s ‘Settled Expectations’ doctrine, which is underpinned by the principle that the longer a patent has been in force, the stronger and more settled the patent owner’s expectations should be. The patents at issue in each of these matters were issued in 2015 and 2017, respectively, long before each of these manufacturers’ petitions were filed.”

Dymbort added, “The USPTO’s decision reinforces our belief in the strength of our TOPCon technology patent portfolio. As we’ve consistently stated, we will actively defend our intellectual property rights in the U.S. and internationally and continue to pursue legal action against these and other manufacturers, as we work to enforce our patent rights.”

First Solar’s TOPCon patents include issued patents in the United States, Australia, Canada, China, the European Union, Hong Kong, Japan, Mexico, Malaysia, Singapore, South Korea, the United Arab Emirates and Vietnam with validities extending to 2030 and beyond. The portfolio also includes pending patent applications in the European Union, Japan, Hong Kong, United Arab Emirates and Vietnam.

First Solar is licensing its TOPCon technology and has already established a relationship with Talon PV, a cell manufacturing startup in Texas.

“The USPTO’s decision not to institute review was based solely on discretionary grounds, which are wholly divorced from the merits of our challenge. While we respectfully disagree with that discretionary denial, we remain confident that when the federal district court considers a full, merits-based review, it will find that the First Solar patent involved is invalid,” stated a spokesperson for JinkoSolar on January 22.