3 OCT 2026 — Most of the world's solar panels use crystalline silicon cells, and a cell design called TOPCon has become one of the most common. First Solar, the largest US-based solar manufacturer, does not make that kind of panel at all. It does own US patents on how TOPCon cells are made, and on 1 October it sued JA Solar, one of the big Chinese producers, along with JA Solar's Vietnam subsidiary and a US company owned by the glassmaker Corning.
The suit is the latest in a campaign First Solar began in 2024, and it targets one of the factories that ship panels into the US from Southeast Asia.
Who is being sued
The complaint, filed in the US District Court for Delaware, names JA Solar Technology, JA Solar International, JA Solar Vietnam and JA Solar Industrial, along with American Panel Solutions, a wholly owned Corning subsidiary, PV Tech reports. First Solar says they infringed US Patent 9,130,074, which covers methods of making TOPCon cells.
The Arizona plant and the Vietnam factory
American Panel Solutions owns the Arizona module-assembly plant that Corning bought from JA Solar last year. JA Solar runs manufacturing bases in China, Vietnam and Malaysia, according to TechNode Global.
Where the patents came from
First Solar makes thin-film panels from cadmium telluride, a different technology. It acquired the TOPCon patents, along with counterparts in Australia, Canada, China, the European Union and elsewhere, when it bought the start-up TetraSun in 2013. The company says their validity runs to 2030 and beyond.
"This lawsuit is an effort to hold JA Solar and AMPS accountable for their unauthorised use of First Solar's patented technology," said Jason Dymbort, First Solar's general counsel.
A patent under challenge
The patent is contested. In May, China's patent office invalidated all its claims in a case brought by JinkoSolar. JinkoSolar and Canadian Solar have also requested reexamination in the United States, TechNode Global reports.
First Solar has already sued JinkoSolar, Canadian Solar, T1 Energy and Trina Solar over TOPCon. Last month it said it would withdraw a complaint at the US International Trade Commission and continue in the district courts, according to PV Tech.
Why the Vietnam unit matters
Naming JA Solar Vietnam brings a Southeast Asian factory directly into a US patent case. If First Solar wins, damages or limits on US sales could reach that factory's output, which is a different kind of pressure from the tariffs that usually decide where panels for the US market are made.
The stakes for First Solar are also commercial. In its most recent quarter, net income rose 23% to $423 million while sales slipped 4%, and it expects more than $2.1 billion this year from US manufacturing tax credits, TechNode Global reports. PV Tech said it had contacted JA Solar and Corning for comment.
