REC Silicon is closing down its polysilicon production plant in Moses Lake, Wash., but it is not walking away.

The plant, which makes solar-grade polysilicon wafers used in solar panels, is a victim of the ongoing trade war between the U.S. and China, the world’s biggest maker of solar panels. The dispute locked REC Silicon out of China, effectively killing its customer base.

As the trade war grinded on, the Norway-based ­company slowed production at the plant and then in mid-May stopped production. It announced July 15 that the plant is being indefinitely shut down, but not closed. About 100 workers at the site were laid off as a result.

The company still has about 100 employees in Moses Lake, REC Silicon CFO James May II told Clearing Up. “That is probably a bit high for basic maintenance.”

REC Silicon retained the workers because it still hopes to reopen the plant, May said.

“We’ve tried to put ourselves in a position where we can restart the facility in the future should the trade war be resolved” or there is significant growth in solar panel production outside China, he said.

However, he noted, there is no indication that ­substantial development outside China is coming.

Nonetheless, losing so many workers means it will take more time to restart the plant, if that day comes.

“This plant is still the most cost-competitive ­polysilicon plant in the world,” he said.

Any cost advantage it has disappears when the plant is operating far below capacity, as it has been since mid-2018 (CU No. 1858 [14]). The plant’s fluidized bed reactor had been operating at 25 percent capacity before shutting down in May.

At 65 percent capacity in the first quarter of 2018, the plant was producing polysilicon for $9.40 per kilogram. At full capacity, it can make it for about $8/kg, “which is about $5 below competition,” May said.

The existing market outside China cannot support enough production for the facility to make a profit.

For now, “we’ll sit in a holding pattern, maintain our other facility” in Butte, Mont., and hope China reopens to polysilicon imports, he said.

The company has slightly more than 200 employees at its Butte plant, which makes silane gas, for a total of about 310 workers in the U.S.

At its height in December 2012, the company employed 832 people in the U.S. Most of them, about 540, worked in Moses Lake. Silane gas produced at its Butte plant was sent to Moses Lake, where the fluidized bed reactor processed it into polysilicon.

The market for silane gas produced at the Butte plant is not affected by the polysilicon tariffs imposed by China, May said.

A considerable amount of industry research has gone into using silane to boost performance of lithium-ion ­batteries. If that proves successful, it would be a boon for the company’s Butte plant, May said. But “if the U.S. loses this ability to manufacture silane gas, it will be at a disadvantage when it comes to the battery market.”