The White House on Thursday imposed a series of ​price floors and a 15% tariff on products made from polysilicon, the raw material used in semiconductors and solar panels that ‌is primarily produced by China.

U.S. President Donald Trump's proclamation under Section 232 of the Trade Expansion Act of 1962 is aimed at supporting domestic chip and solar supply chains needed to compete with Beijing on artificial intelligence and energy.

"The plan of action in this proclamation will, among other things, help ensure the commercial viability of United States production ​of polysilicon and its derivatives that is necessary to meet United States economic and national security requirements," the order said.

Polysilicon, an ultra-pure ​form of silicon, sits at the start of the semiconductor and solar manufacturing supply chains. Manufacturers turn silicon ⁠wafers into solar cells and then assemble those into panels used in solar projects.

American solar factories for the last decade have accused their Chinese rivals ​of dumping solar panels in the market, receiving unfair government subsidies and moving their manufacturing to other countries to dodge U.S. tariffs.

The United States has two ​polysilicon factories. Hemlock Semiconductor, which operates a plant in Michigan, is a joint venture between Corning and Japan's Shin-Etsu Handotai. Munich-based Wacker Chemie runs a factory in Tennessee.

"Today's decision encourages continued investment in U.S. capacity and supports long-term U.S. competitiveness," a Corning spokesperson said.

Wacker said it was reviewing the actions to fully understand their impact.

"We appreciate ​the Administration's continued engagement on the issue given the ramifications for semiconductor supply chain resilience, advanced computing infrastructure, and broader U.S. defense and security ​interests," the company said in a statement.

Domestic semiconductor manufacturing depends on solar because the solar industry's larger demand for polysilicon helps support production of the material required for ‌chips. The ⁠chip industry accounts for 2.4% of global polysilicon demand, according to the Semiconductor Industry Association.

U.S. solar manufacturing has expanded since Congress created tax incentives in 2022. Much of that growth, however, has been concentrated in panel assembly, leaving manufacturers dependent on imported wafers and cells, which require longer investment timelines.

Companies with U.S. solar factories, including T1 Energy, First Solar and Qcells, the U.S. solar arm of South Korea's Hanwha, applauded Trump's move.

"This is a decisive win for advanced American ​manufacturing and investment in domestic energy ​supply chains," Dan Barcelo, CEO of ⁠T1 Energy, said in a statement. In addition to its Texas solar panel plant, T1 is investing $510 million in a cell factory.

The trade protections will take effect on December 4, the White House said.

Tim Brightbill, a trade ​attorney with Wiley Rein who has brought several trade cases against Chinese solar companies, warned that the ​delayed implementation could lead ⁠to a surge of imports in the coming months.

Companies that buy solar panels have argued that the delay is needed to adjust supply contracts to higher prices.

According to a White House document, the president set minimum import prices of $21 per kilogram for polysilicon, $100 per kilogram for polysilicon ingots and wafers, $0.22 per watt ⁠for solar ​cells and $0.38 per watt for solar modules, or panels.

The proclamation also authorises the Commerce Department ​to create an incentive program for companies that invest in factories to produce polysilicon or derivative products.

The administration's plan to pursue a hybrid system combining a minimum import price with tariffs was ​first reported by Reuters.