(Adds SolarWorld comment, background on trade cases, import data)
WASHINGTON, July 25 (Reuters) - The United States on Friday set new import duties on solar products from China and Taiwan after the Commerce Department found that the solar panels and cells are being sold too cheaply on the U.S. market.
Preliminary anti-dumping duties as high as 165.04 percent for Chinese goods would come on top of anti-subsidy levies imposed last month, as the U.S. arm of German solar manufacturer SolarWorld AG seeks to close a loophole allowing Chinese producers to sidestep duties imposed in 2012.
China's Trina Solar faces total import duties of nearly 30 percent and Suntech Power nearly 50 percent as a result of Friday's decision.
Taiwanese producers face anti-dumping duties of up to 44.18 percent, with the highest rate applying to Motech Industries , Commerce said. There will be no doubling-up of duties with those from the 2012 case.
The new duties, which must still be confirmed, are likely to inflame U.S.-China tensions already exacerbated by recent accusations that Chinese military officers were cyber-spying on U.S. companies involved in trade disputes, including SolarWorld.
SolarWorld said the new duties would average 47 percent for most companies, compared with 31 percent in the 2012 case.
The company, which makes crystalline silicon solar panels in Oregon, complained that Chinese manufacturers dodged those duties by shifting production of the cells used to make their panels to Taiwan.
"Today's actions should help the U.S. solar manufacturing industry to expand and innovate," said SolarWorld Industries America President Mukesh Dulani. "We should not have to compete with dumped imports or the Chinese government."
The solar industry has been battered over the last four years by a glut of products from China, falling prices and a withdrawal of consumer subsidies in Europe, which has pressured solar companies' margins and sparked a rash of trade cases.
India has slapped levies on panels from the United States and China. The European Union also has targeted Chinese panels and China has moved against imports of U.S. polysilicon, solar's key raw material.
Meanwhile, the United States is challenging India's solar program at the World Trade Organization. The WTO found irregularities in the previous U.S.-China anti-subsidy case.
SolarWorld has said it has the support of other U.S. solar manufacturers in pushing for a broadening of the duties.
But the Coalition for Affordable Solar Energy, which represents about 50 companies that mainly focus on installation, has criticized the case and said installers would suffer if there was another jump in the cost of modules.
U.S. imports of solar products from China were worth $1.5 billion in 2013, half the level of 2011, while imports from Taiwan more than doubled to $657 million over the period, according to Commerce data.
Commerce will make its final decision by Dec. 15. The U.S. International Trade Commission is due to make a decision on whether the imports pose or threaten injury to U.S. producers by Jan. 29. (Reporting by Krista Hughes; Editing by Paul Simao)