Background
Trina Solar, one of the world’s largest solar panel manufacturers, holds patents on TOPCon (Tunnel Oxide Passivated Contact) solar cell technology — a next-generation photovoltaic cell design that achieves higher efficiency than conventional PERC cells by using an ultra-thin tunnel oxide layer to passivate the silicon surface. TOPCon technology has become the dominant architecture for premium solar panels, and the IP landscape around it has grown increasingly contested as Chinese and Canadian manufacturers compete for global market share.
Trina Solar asserted two TOPCon patents against certain Canadian Solar subsidiaries. Canadian Solar responded by filing inter partes review (IPR) petitions at the PTAB, challenging the validity of all claims in both patents. The petitions argued the claimed inventions were anticipated or obvious in light of prior art.
The dispute is part of a broader global patent war between the two solar giants. In February 2025, Trina Solar also sued Canadian Solar in China for alleged infringement of two TOPCon patents, seeking approximately $147 million in damages.
The Court’s Holding
The PTAB issued Final Written Decisions invalidating all claims in both of Trina Solar’s asserted TOPCon patents. The Board found that the challenged claims were unpatentable over the prior art presented by Canadian Solar.
The decisions effectively eliminate these patents as a barrier to Canadian Solar’s TOPCon-related operations in the U.S. market. Trina Solar may appeal to the Federal Circuit, but as of the decision date, the patents are no longer enforceable.
Key Takeaways
- Both of Trina Solar’s asserted TOPCon patents were fully invalidated — not just selected claims — which is a complete victory for Canadian Solar at the PTAB stage.
- The decisions remove a significant IP overhang for Canadian Solar and other TOPCon manufacturers selling into the U.S. market.
- TOPCon technology is rapidly becoming the industry standard for high-efficiency solar cells, making patent disputes in this space commercially significant — market access is at stake, not just royalties.
- The global nature of the dispute (parallel litigation in China seeking $147 million) illustrates how solar IP battles are fought across multiple jurisdictions simultaneously.
Why It Matters
The solar industry is in the middle of a technology transition from PERC to TOPCon, and the companies that control the IP around TOPCon manufacturing methods will have significant leverage over competitors. These PTAB decisions weaken Trina Solar’s patent position in the U.S., potentially emboldening other manufacturers to pursue TOPCon production without licensing from Trina. For the broader clean energy sector, the case highlights how patent strategy has become a critical competitive tool — not just for excluding competitors, but for shaping market access and supply chain decisions in an industry increasingly driven by trade policy and tariff considerations.