US government advances new trade measures to counter China’s solar supply chain

President Donald Trump signed a presidential proclamation on August 6 introducing a 15% tariff on downstream polysilicon derivatives, including ingots, wafers, cells, and modules. The action, taken under Section 232 of the Trade Expansion Act, frames China’s dominance over the solar supply chain as a national security threat and attempts to rebuild a domestic manufacturing base that has effectively vanished over the past two decades.

The tariffs are set to take effect on December 4, 2026.

What the new tariffs actually look like

Beyond the flat 15% ad valorem rate, the proclamation establishes minimum import prices designed to prevent foreign producers from undercutting US manufacturers through aggressive pricing. Polysilicon faces a floor of $21 per kilogram. Ingots and wafers carry a minimum of $100 per kilogram. Solar cells must clear $0.22 per watt, and finished modules $0.38 per watt.

The proclamation also includes domestic content requirements that ratchet up over time. Manufacturers must hit a 50% domestic content threshold by 2026, rising to 80% by 2029. That’s an aggressive timeline for an industry where the US currently accounts for less than 2% of global polysilicon production.

For context, the US held roughly half the world’s polysilicon production capacity back in 2005. Two decades later, China controls more than 90% of global output.

A familiar playbook, turned up a notch

This isn’t Washington’s first attempt to shield US solar manufacturing from Chinese competition. The original anti-dumping and countervailing duty investigations targeting Chinese solar cells and modules kicked off in 2012. Those duties were extended and modified over the years through 2024, but they clearly didn’t reverse the underlying trend.

Chinese manufacturers adapted by routing production through Southeast Asian countries like Vietnam, Thailand, Malaysia, and Cambodia. Section 232 represents a more aggressive legal framework. It’s the same authority used to impose steel and aluminum tariffs, and it gives the president broad unilateral power to restrict imports deemed harmful to national security.

Polysilicon is a critical input for both solar panels and semiconductor manufacturing, representing a dual-use vulnerability across energy infrastructure and chip fabrication.

Industry reaction and market dynamics

Several domestic manufacturers have already signaled their support. T1 Energy, First Solar, and Qcells, three of the most prominent US-based solar panel producers, have publicly backed the measures.

First Solar in particular stands to benefit. The company has long differentiated itself by manufacturing thin-film solar panels domestically, a strategy that looked expensive when Chinese crystalline silicon modules were flooding the market at rock-bottom prices.

With a four-month window between announcement and enforcement, importers have every incentive to stockpile inventory. That dynamic could create a temporary glut of cheap panels in the US market, followed by a sharp price adjustment once the tariffs bite around the December 4 implementation date.

The 80% domestic content requirement by 2029 is arguably the most consequential element of the entire package. Meeting that target would require billions of dollars in new US manufacturing capacity across multiple stages of the production process, from raw polysilicon refining to cell fabrication to module assembly.

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