China’s Ministry of Commerce said on Wednesday that it will impose two-year anti-dumping and anti-subsidy duties on imports of solar-grade polysilicon from the European Union (EU) beginning from May 1.

A final ruling by the ministry found that the EU products were dumped and subsidized in the Chinese market and caused substantial damage to domestic producers during the period of investigation.

The ministry launched the probe on Nov. 1, 2012 in response to requests filed by Chinese polysilicon manufacturers amid an import surge and price decline of the EU products. On Oct. 31, 2013, the ministry announced that it would extend the probe by another six months to May 1, 2014.

Solar-grade polysilicon is a key material for making solar cells.