The headquarters of the United States Patent and Trademark Office in Alexandria, Virginia, United States
Image: Coolcaesar, Wikimedia Commons, CC BY-SA 3.0
The director of the United States Patent and Trademark Office has denied three separate review applications seeking to invalidate patents related to Frist Solar’s tunnel oxide passivated contact technology (TOPCon).
JinkoSolar and Canadian Solar attempted to invalidate U.S. Patent No. 9,130,074, while Mundra Solar challenged U.S. Patent No. 9,666,732. Both patents relate to methods for the production of solar cells.
The decision to reject the assessments leaves the patents intact while First Solar pursues an infringement lawsuit in the United States District Court for the District of Delaware.
First Solar acquired the patents through its purchase of Silicon Valley startup TetraSun in 2013. The company announced its intention to license and enforce the portfolio in July 2024.
The company has since filed lawsuits alleging that competitors are using its patented methods without authorization to produce high-efficiency crystalline silicon modules.
The manufacturer noted that the patents were issued in 2015 and 2017. First Solar said the denials are consistent with the “doctrine of fixed expectations.” The doctrine is based on the idea that the longer a patent remains in force without being successfully challenged, the “firmer” the owner’s rights become.
In early 2025, First Solar entered into a licensing agreement for the technology with Talon PV, a manufacturer planning a 4 GW cell facility in the United States. Other companies in the crystalline silicon market, including Trina Solar, have also launched their own investigations into possible infringements of TOPCon patents as the technology becomes the dominant architecture for the global industry.
First Solar has international counterparts of these patents in China, Japan and the European Union, among others. The company has indicated that it will continue to take legal action against manufacturers it believes are infringing its rights.
First solar energy issued a warning to shareholders and competitors in November 2024 alleging that the Longi, Trina Solar, Jinko Solar, JA Solar and Canadian Solar were using the First Solar TOPCon patents without a license.
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