Chinese wind turbine generator suppliers weren't yet a major factor in Europ

"The whole [renewable energy] industry is going to struggle for a few years because of overcapacity," said Tom Murley, head of the renewable energy team at HG Capital, which manages €845 million ($1.07 billion) in renewable energy equity. "There will be more supply than demand probably for another five years in the wind sector."

During the first half of the last decade, Germany, Spain and the U.S. were responsible for the majority of the increase in wind power capacity, according to the International Energy Agency. Now, "the center of gravity for wind energy markets has begun to shift to Asia, namely to China," the IEA said in a November report. In 2010, half of all new wind-power capacity was installed in China, it said.

The rise of China has also meant the rise of Chinese renewable companies—both wind turbines and solar-power firms—and more potential competitors for incumbents. A recent report by Bernstein Research cited recent contract wins by Chinese wind-turbine makers in Ireland, Greece and the U.S. The tough environment "will continue to depress mature market turbine pricing," Bernstein said.

Vestas Chief Executive Ditlev Engel said Chinese wind turbine generator  suppliers weren't yet a major factor in Europe. "Until now we haven't seen the Chinese producers yet, but that can change in coming years," he said.