China's green energy industry has long been seen as a world-beater. But domestic pressures are mounting on its renewables firms as growth slows; and analysts are warning that Chinese companies could respond by accelerating their expansion overseas, stoking a rising east-west tension in the race towards a low-carbon economy.

The European commission has just followed up US trade action against China by announcing its own investigation into allegations that Bejing firms are "dumping" cheap solar panels in European markets.

But Chinese green companies are being hit at home by logjams on the power grid, the wider national economic downturn and increased competition of their own.

Longyuan, China's biggest wind farm operator, has cut its projected new power installations from 2 gigawatts (GW) in 2011 to 1.6GW this year and says it now wants to expand in the US, South Africa and Hungary. It has just pushed rival Iberdrola of Spain off the global top slot, according to a new report from Make Consulting.

Meanwhile, the grid problems and other issues have led Chinese wind-turbine maker Sinovel to report a 96% dive in first-half profits, while sales income was down by almost half.

Sinovel is the second largest of its kind in the world behind Vestas of Denmark, while Goldwind (third biggest) recently reported an 83% plunge in first-half profits on the back of a 42% slump in sales.

These setbacks may be temporary and are expected to increase Chinese activity overseas, rather than reduce it, according to Robert Clover, research director of Make Consulting. He says: "China has seen 50% compound growth [in wind energy] since 2005 but is now taking a pause … There is no doubt that manufacturers of turbines and asset owners [wind-farm operators] are now looking at international markets for growth."

And there are already signs that Chinese and other Asian firms are buying European rivals that have been hit by the credit crunch, the running-down of local subsidies and low-cost competition from abroad.

One high-profile example of this has been revelations that Mitsubishi of Japan has been talking about buying a stake in Vestas, whose share price has been hit by a series of problems.

The Danish wind-turbine maker, which has issued a series of profit warnings and has been through a major board and management team upheaval, has already sold off a wind turbine tower factory at Varde in Denmark to China's Titan Wind Energy.

And this comes at the same time as the financially stricken German solar business Q-Cells, once a world leader, has been rescued from the liquidators by Hanwha Chemical of South Korea. Another major German solar business, Solon, which has also in been in financial trouble, was bought earlier this year by the Indian firm, Microsol.

Meanwhile, China's Guangdong Aiko Solar Energy this summer bought collapsed Dutch business Scheuten Solar, while Ascent Solar – maker of solar-powered iPhone chargers – has fallen under the majority control of Chinese-Singaporean joint venture TFG Radiant.

But while these takeovers are creating controversy, there is also considerable relief that hundreds of jobs are potentially being saved by Asian-backed rescue missions.

The insolvency administrator handling the Q-Cells collapse, Henning Schorisch, said: "I am very happy Q-Cells has found a strong partner in Hanwha, which has the means to provide company, brand and staff with long-term perspectives again."

And state-owned Chinese energy company Three Gorges Corporation helped the Portuguese government by buying a major stake in the local utility, EDP, which is now a backer of plans to construct the world's largest wind complex – 1.5GW – off Caithness in northern Scotland.

Britain itself has made no secret of its desire to allow state-owned Chinese companies to become involved in a range of new atomic power stations as well as buy North Sea oil fields.

Clover says: "Companies such as Three Gorges not only bring their own fresh capital but Chinese lines of credit at a time when lending from many western banks is constrained."