The world’s largest solar cell manufacturer Q-Cells SE has withdrawn its full-year sales outlook sending shares across the sector lower, Reuters reports.

Along with its competitors, Q-Cells has been hit by a steep decline in prices for solar cells, mainly caused by an oversupply that built up during the boom years of 2007 and 2008.

“The prolonged weak development of the global photovoltaic markets has continued to negatively impact the business development of Q-Cells SE in the second quarter,” the company said.

Q-Cells said it no longer expects sales to reach €1.3bn-€1.6bn ($1.81bn-$2.23bn), adding that it will not be possible to make a reliable forecast now.

Shares in German solar stocks fell on the news, with Q-Cells leading the pack, down 11.4%, while peers SolarWorld, Solon, and Phoenix Solar were all down 2.2% to 4.1%, writes Reuters.