“Our action today is an emergency measure to give lifesaving oxygen to a business sector in Europe that is suffering badly from this dumping,” Mr. De Gucht said.

“This is not protectionism,” he insisted, noting that the United States had also applied duties totaling about 30 percent to Chinese solar exports. But the Obama administration recently decided to seek its own negotiated settlement with China to replace the tariffs.

Saying Chinese exporters had captured 80 percent of the European Union’s market for solar panels, he suggested that “massive overcapacity” in China had led the Chinese to flood the European market. China is “producing today one and a half times the amount of solar panels the world needs,” he said.

A majority of the European Union’s governments were officially opposed to putting the preliminary tariffs in place. But under the bloc’s rules, they faced significant obstacles to stopping Mr. De Gucht, who had the backing of the European Commission, the group’s executive branch. Under European Union rules, preliminary tariffs can be turned into five-year tariffs six months later. But that would require a majority of the bloc’s member governments to approve the move.

Individual Western companies, in the solar industry and other sectors, have been wary of taking any public stand against China, which has become the world’s largest market in industries as diverse as steel, cellphones and automobiles. Chinese officials have considerable discretion in issuing factory permits, export licenses and even visas for visiting executives, making most companies leery of publicly voicing criticism of China or being seen as supporting trade actions against it.

In a nod to the heavy lobbying in Europe against the duties, Mr. De Gucht said that “cheap and plentiful seems great, but ultimately this will lead to a race to the bottom” where “everyone loses.”

Asked Tuesday whether he had succumbed to political pressure, particularly from Germany, Mr. De Gucht insisted that he had chosen a “reasonable” middle ground by giving the Chinese 60 days “to come to an amicable solution” before imposing the maximum rate of 47.6 percent.