U.S.-based solar module manufacturer First Solar has filed a lawsuit against Shanghai-headquartered JinkoSolar, alleging patent infringement of its tunnel oxide passivated contact (TOPCon) modules.

The lawsuit was filed in the U.S. District Court for the District of Delaware.

First Solar alleged infringement of its U.S. patent number 074, which covers methods of manufacturing TOPCon crystalline silicon solar cells.

The company obtained the U.S. TOPCon patents and related international counterparts by acquiring silicon cell developer TetraSun in 2013.

The patents are recognized in the U.S., Australia, Canada, China, the European Union, Hong Kong, Japan, Mexico, Malaysia, Singapore, South Korea, the United Arab Emirates, and Vietnam. The patent validity has been extended beyond 2030.

It also includes pending patent applications in the European Union, Japan, Hong Kong, the United Arab Emirates, and Vietnam.

The solar industry is transitioning from monocrystalline passivated emitter and rear contact cells to TOPCon technology, and countries are increasingly emphasizing domestic solar manufacturing. This change drove a recent surge in TOPCon-related intellectual property disputes, particularly in China, Europe, and the U.S.

In July 2024, First Solar announced its ownership of the TOPCon technology patent portfolio and the launch of its infringement investigations against multiple crystalline silicon solar cell manufacturers.

Jason Dymbort, Executive Vice President, General Counsel, and Secretary of First Solar, said, “We’ve been clear that we will actively defend our intellectual property rights in the U.S. and internationally. Unfortunately, our interaction with JinkoSolar has been unproductive and left us with no choice but to enforce our patent rights through legal action,”

He added that First Solar believes it has a strong TOPCon technology patent portfolio after considering the responses from other solar cell manufacturers in connection with the infringement investigations.

“We expect that our lawsuit against JinkoSolar will reiterate the need for TOPCon solar cell manufacturers to operate within the well-defined framework of intellectual property law,” he said.

Recently, US-based crystalline silicon solar cell manufacturer Talon PV secured the license for TOPCon cell manufacturing patents from First Solar.

In January 2025, the U.S. International Trade Commission terminated an investigation into the global provider of utility-scale wire (solar, electrical balance of systems) solutions company Voltage’s patent infringement through its LYNX trunk bus solution.