Aug 4 (Reuters) - The Trump administration is preparing to set a price floor and impose tariffs on polysilicon and related products, according to four people familiar with the plan, putting a material critical to solar panels and semiconductors at the center of U.S. efforts to compete with China on artificial intelligence and energy.

The decision, expected to come later this month, aims to protect U.S. polysilicon factories owned by Hemlock Semiconductor and Wacker Chemie from growing Chinese ambitions in the chip supply chain. Hemlock, which operates a plant in Michigan, is a joint venture between Corning and Japan's Shin-Etsu Handotai.

The administration is expected to pursue a hybrid system combining a minimum import price with tariffs on polysilicon and derivative products, according to the sources familiar with the deliberations, who spoke on condition of anonymity.

Two of the sources said the plan will allow importers investing in U.S. wafer and cell production to offset the costs associated with the trade protections. China accounts for roughly 80% of global solar manufacturing capacity.

A White House official would not comment ahead of President Donald Trump's decision. The Commerce Department did not respond to a request for comment.

China's Embassy in Washington criticized the trade investigation.

"China urges the U.S. to stop the Section 232 tariff measures as soon as possible, and properly resolve the concerns of all parties through equal dialogue," a spokesperson said.

Section 232 of the Trade Expansion Act authorizes the president to restrict imports deemed a threat to national security. Trump has previously used the authority to impose tariffs on products including steel, autos and semiconductors.