Trump Imposes 15% Tariff on Polysilicon to Bolster US Solar, Chip Supply

President Donald Trump signed an executive order Thursday imposing a 15 percent tariff on imported products made from polysilicon, a critical input for both solar panels and advanced semiconductors. The measure, set to take effect December 4, also establishes minimum prices on certain related imports and relies on Section 232 of the Trade Expansion Act of 1962, the same provision used for earlier steel and aluminum duties.

Polysilicon is an ultra-pure form of silicon that sits at the beginning of two major supply chains. It is refined into wafers that become solar cells or are processed further into the chips that power data centers and artificial intelligence systems. China dominates global production, and U.S. manufacturers have long argued that state subsidies and excess capacity allow Chinese firms to sell below cost. The new duties aim to improve the commercial position of the two remaining U.S. polysilicon plants, one operated by Hemlock Semiconductor in Michigan and another by Wacker Chemie in Tennessee.

White House officials described the action as necessary to safeguard economic and national security requirements. The order states that decades of import pressure have eroded domestic capacity and left the United States dependent on foreign suppliers for materials essential to both clean energy and advanced computing. Commerce Secretary Howard Lutnick provided the underlying findings that justified the Section 232 investigation.

Financial markets registered an immediate reaction. Shares of First Solar rose more than 7 percent in premarket trading, while the Invesco Solar ETF gained roughly 4 percent. Analysts noted that domestic panel makers stand to benefit from higher prices on Chinese-derived inputs, though the extent of the advantage will depend on how strictly the minimum-price rules are enforced.

Chinese officials condemned the move. A foreign ministry spokesperson said the United States was stretching the concept of national security and disrupting normal commercial exchanges. Beijing has previously responded to similar tariffs by shifting assembly operations to third countries and by filing complaints at the World Trade Organization.

Domestic industry reactions were more measured. A Corning spokesperson, whose company holds a stake in Hemlock, welcomed the decision as support for continued investment. Wacker Chemie said it was still reviewing the details to assess effects on its Tennessee operations and on downstream customers.

The policy arrives amid ongoing efforts to expand U.S. semiconductor fabrication capacity under the CHIPS Act and to accelerate solar deployment through Inflation Reduction Act incentives. Whether the new tariffs complement those programs or raise input costs for manufacturers that rely on imported polysilicon remains an open question. Supply-chain data show that even with recent factory announcements, the United States still imports the large majority of its polysilicon and finished panels. The tariff therefore functions less as an immediate onshoring tool and more as a long-term signal to investors weighing multi-year commitments in domestic refining capacity.