China’s Ministry of Commerce (MOFCOM) has announced a further five-year extension of anti-dumping duties on solar-grade polysilicon imports from the United States and South Korea, originally imposed in 2014.

Under the decision, duties on U.S. producers will continue to range from 53.3% to 57%, while South Korean companies will face tariffs of between 2.4% and 48.7%. The measures will remain in force until 2031.

The U.S. companies covered by the duties include REC Solar Grade Silicon LLC, REC Advanced Silicon Materials LLC, Hemlock Semiconductor Corp., MEMC Pasadena Inc., and AE Polysilicon Corp. Affected South Korean producers include OCI Co. Ltd., Hankook Silicon Co. Ltd., Hanwha Solutions Corp., SMP Corp., Woongjin Polysilicon Co. Ltd., KCC Corp., Korean Advanced Materials (KAM Corp.), and Innovation Silicon Co. Ltd. However, many of these firms are no longer active suppliers of polysilicon to the photovoltaic (PV) industry.

MOFCOM initiated a sunset review of the duties in January 2025 after receiving a request from 13 Chinese polysilicon producers, led by Sichuan Yongxiang Polysilicon. The applicants argued that removing the measures could result in renewed dumping of U.S. and South Korean polysilicon into the Chinese market, causing material harm to the domestic industry.

China first extended the anti-dumping duties in 2020 for a five-year period. MOFCOM said the latest review request, along with the supporting evidence, met the legal requirements for a final review, ultimately leading to the decision to maintain the tariffs.

The original duties were introduced in 2014, with rates set at 53.3% to 57% for U.S. producers and 2.4% to 48.7% for South Korean manufacturers. In 2017, China adjusted the tariff structure, with some rates rising as high as 113.8%.

European polysilicon suppliers—primarily German producers—were excluded from the 2014 measures following a bilateral agreement between China and Germany.