The Department of Commerce launched a Section 232 national security investigation into polysilicon and its derivatives on July 1, 2025. A public comments notice followed on July 16.

Section 232 investigations are the same legal mechanism the first Trump administration used to slap tariffs on steel and aluminum imports back in 2018. The tool gives the president broad authority to impose trade restrictions when imports are deemed a threat to national security.

The Commerce Department is expected to submit its report around May 2026, with a presidential decision now pushed back to August 2026.

In January 2026, proposals emerged for establishing price floors on critical minerals, a mechanism where adjustable tariffs would kick in to maintain minimum trading prices. VP JD Vance detailed these plans further in February 2026.

If the global price of polysilicon drops below a certain threshold, likely because Chinese producers are flooding the market with cheap supply, tariffs would automatically adjust upward to keep the effective US price above a set minimum.

Polysilicon isn’t exactly a household name, but it’s the silicon-based material refined to extreme purity levels for two very different end uses. Solar-grade polysilicon gets turned into the wafers that make up photovoltaic panels. Electronic-grade polysilicon, refined to even higher purity, feeds the semiconductor supply chain.

China accounts for the majority of global polysilicon supply. The US domestic production landscape is thin. Hemlock Semiconductor in Michigan and Wacker Chemie’s facility in Tennessee represent the primary American producers. REC Silicon, which operated in Washington State, has faced significant operational challenges.

The Inflation Reduction Act, passed in 2022, poured billions into incentivizing domestic solar manufacturing and clean energy deployment. The administration’s polysilicon push is, in part, an attempt to make the IRA’s domestic manufacturing ambitions actually achievable.

Tariffs and price floors on polysilicon will almost certainly raise input costs for US solar panel manufacturers and semiconductor producers. Higher polysilicon prices mean more expensive panels, which means longer payback periods on installations, which means some projects that pencil out today might not pencil out tomorrow.

For domestic polysilicon producers like Hemlock Semiconductor, a guaranteed price floor effectively provides revenue certainty, making it easier to justify capacity expansion investments.

The investigation’s outcome isn’t binary. The president could impose blanket tariffs, targeted tariffs, quotas, or some combination with exemptions. Each scenario produces different winners and losers across the solar and semiconductor value chains.