The U.S. is launching an investigation into whether Chinese solar-equipment manufacturers are evading tariffs by sending components to other Asian nations for assembly before shipping finished products to the U.S.

The U.S. Commerce Department said in filings Monday that it would open the probe requested by Auxin Solar Inc., a small California panel maker, marking the first formal step of an investigation that could span a year and culminate in expanded duties on the imports.

The investigation threatens to upend the U.S. solar sector, which depends heavily on Asian panels. Companies that build solar farms warned that simply opening a probe will drive up prices and potentially expose importers to retroactive duties. That could slow the growth of clean power in the U.S. and undermine President Joe Biden’s goal of eliminating carbon dioxide emissions from the electricity sector by 2035.