The U.S. Patent and Trademark Office (USPTO) director has denied three separate inter partes review applications filed by JinkoSolar, Mundra Solar, and Canadian Solar in 2025, seeking to invalidate First Solar’s technology patents, covering methods of manufacturing TOPCon crystalline silicon solar cells.

The applications filed by the three companies were declined on November 20, 2025, and December 11 and 18, 2025, respectively.

First Solar stated that it has pending lawsuits against the three applicants in the Delaware District Court, alleging infringement of its patents.

The company added that the USPTO’s decision was consistent with the ‘settled expectations’ doctrine. Under this doctrine, the patent owner’s expectations will depend on how long a patent has been in force.

First Solar said the patents at issue with its USPTO were issued in 2015 and 2017, respectively, well before the three companies filed their applications.

First Solar received the U.S. TOPCon patents and their international counterparts through its 2013 acquisition of TetraSun. The company also obtained patents for its TOPCon technology in Australia, Canada, China, the European Union (EU), Hong Kong, Japan, Mexico, Malaysia, Singapore, South Korea, the United Arab Emirates (UAE), and Vietnam. The validity of these patents extends to at least 2030.

Additionally, First Solar has pending patent applications with the EU, Japan, Hong Kong, the UAE, and Vietnam.

First Solar announced its plans to license and enforce its TOPCon technology patent portfolio and initiate the infringement investigations against multiple leading crystalline silicon solar cell manufacturers in 2024.

As the solar industry transitions from Mono PERC to TOPCon technology and countries emphasize domestic manufacturing, there has been a surge in intellectual property disputes related to TOPCon solar recently, particularly in China, Europe, and the U.S.

Earlier, the Patent Trial and Appeal Board of the USPTO determined that the claims of patent infringement by Singapore-based solar solutions provider Maxeon Solar Technologies against Canadian Solar are invalid.