A high-stakes fight that mixes renewable power, international relations and cyberespionage threatens to slow the American solar industry’s rapid growth.

Last week, U.S. Department of Commerce officials tentatively agreed to slap tariffs as high as 35 percent on much of the solar equipment American companies import from China.

SolarWorld, a German company whose U.S. base is in Oregon, sought the tariffs, claiming China’s government has unfairly subsidized its solar manufacturers and flooded the world with cheap panels. It’s a familiar argument to anyone who remembers the 2011 bankruptcy of Solyndra, the federally funded startup that made tube-shaped solar panels in Fremont until plunging prices drove it out of business.

But many U.S. companies have come to rely on cheap panels from China. And they want SolarWorld to back off.

Companies that install, sell or lease solar arrays have seen their business boom as panel prices fall, tumbling 70 percent since the start of 2010. Tariffs, they say, will make solar power less affordable and slow its rapid spread across the country.

“It’s going to do a huge amount of damage to the installers and developers,” said Rhone Resch, chief executive officer of the Solar Energy Industries Association.

His trade group has been trying to broker a […]