The U.S. Commerce Department on Tuesday announced anti-subsidy countervailing duties on solar cells imported by companies in Vietnam, Cambodia, Malaysia and Thailand, a move that could make it more expensive both to produce and buy solar panels in the United States.

The announcement is the first of two preliminary decisions expected by the Commerce Department this year in a trade case brought by Korea's Hanwha Qcells, Arizona-based First Solar and several smaller companies seeking to protect billions of dollars in investments in U.S. solar manufacturing.

The group, calling itself the American Alliance for Solar Manufacturing Trade Committee, accused Chinese companies with factories in the four countries of flooding the U.S. market with panels priced below their cost of production and of receiving unfair subsidies that make American products uncompetitive.

Others in the solar industry say those low-priced imports are critical for both clean-energy project developers competing with fossil fuels and for domestic solar factories that use overseas-made cells in panels assembled on U.S. soil.

According to a fact sheet posted on the Commerce Department's website, the agency calculated general subsidy rates of 9.13% for imports from Malaysia, 8.25% for imports from Cambodia, 23.06% for imports from Thailand and 2.85% for imports from Vietnam.

Large manufacturers have their own separate duty rates. For instance, Commerce calculated a duty rate of just 0.14% for products made by China's Trina Solar in Thailand.

Commerce calculated a duty rate of 14.72% for products produced in Malaysia by one of the companies behind the petition, Hanwha Qcells.

Representatives for Trina and Hanwha were not immediately available for comment.

An attorney for the American Alliance for Solar Manufacturing Trade Committee, Tim Brightbill, said the department's findings were in line with expectations and that the final decision could yield higher duties.

"Some of the margins definitely do not yet reflect the full extent of government subsidies that are occurring in the industry," Brightbill said on a call with reporters.

A final order will be made in April next year.