President Donald Trump has signed a proclamation imposing an additional tariff and an import price floor on polysilicon, a key material for semiconductors and solar panels, set to take effect in December 2026.
US President Donald Trump signed a proclamation on August 6, 2026, imposing an additional tariff and an import price floor regime on polysilicon and its derivative products. Titled “Adjusting Imports of Polysilicon and its Derivatives into the United States,” the text aims to rebuild a domestic US supply chain for this material, which is essential to semiconductor and solar panel manufacturing. Both mechanisms are set to take effect simultaneously on December 4, 2026, according to the proclamation. Will Scharf, White House staff secretary, presented the measure on the day it was announced.
Polysilicon sits upstream of two distinct but connected industrial chains. In semiconductors, it is used to manufacture the silicon wafers used in chips; in solar, it feeds the production of cells and then photovoltaic modules, such as those deployed in projects like the Rockhound solar complex operated by Origis Energy in Texas. According to the White House, the US share of global polysilicon production capacity has become marginal in the face of rising foreign producers, led by China. Howard Lutnick, Secretary of Commerce since February 21, 2025, initiated the recommendations that underpinned the proclamation.
The expansion of solar farms worldwide, exemplified by the Fleming solar plant developed by GRS and Acciona Energía, illustrates growing demand for photovoltaic modules and, further upstream, for polysilicon. Washington intends to secure a supply it considers strategic, both for the electronics industry and for domestic solar power production.
The measure goes beyond a simple tariff increase. An import price floor regime prevents the sale of polysilicon or its derivatives below a level deemed consistent with undistorted market conditions; any importer unable to certify a resale price at least equal to this threshold faces a compensatory tariff equal to the gap observed. In addition, an ad valorem additional tariff applies specifically to polysilicon ingots and the products derived from them — wafers, cells and solar modules — with adjustments based on origin for certain trading partners.
An incentive component rounds out the framework: the Secretary of Commerce is authorized to negotiate with companies that commit to building, expanding or modernizing production facilities on US soil, in exchange for tariff relief. This mechanism follows a pattern already applied to other materials deemed strategic, such as steel, aluminum and semiconductors themselves, which have also been targeted by similar measures in recent months, echoing the demand seen in projects such as the two solar farms approved in Colombia.
The proclamation follows an investigation opened on July 1, 2025, by the Department of Commerce, based on Section 232 of the Trade Expansion Act of 1962, which authorizes the president to restrict imports deemed a threat to national security. About a year elapsed between the opening of this investigation and the signing of the proclamation. This process differs from tariffs based on the International Emergency Economic Powers Act (IEEPA), which the US Supreme Court ruled unauthorized in a decision issued on February 20, 2026 — a ruling with no bearing on the polysilicon measure, which was adopted on a separate legal basis.
A spokesperson for the Chinese Embassy in Washington had criticized the investigation before the proclamation was signed. By contrast, Andy Park, global chief executive officer of Hanwha Qcells, a South Korean company operating a solar panel plant in the United States, welcomed the decision.
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