Solar cells and modules incorporating SunPower’s Interdigitated Back Contact (IBC) cell technology have been granted an exemption from the Section 201 duties that the Trump Administration imposed on imported solar products.

The exemption is specifically for IBC cells and modules made from cells that have “more than 100 interdigitated fingers of tin-coated solid copper adhered to the back of the cell, with the copper portion of the metal fingers having a thickness of greater than 0.01 mm”. It was unclear at the time of writing whether or not this would apply to IBC products from LG, which is the only other major PV maker with IBC products.

This exclusion will be effective on September 19, when filed in the Federal Register. According to SunPower this will not be retroactive, meaning that any tariffs paid over the last seven months following the imposition of duties on February 6 will be lost.

SunPower filed for an exemption in March, and this is a major win for a company that has made a number of major sacrifices in a struggle to get to profitability. It also gives SunPower a relative advantage against other suppliers of high-efficiency solar modules to the residential and commercial and industrial markets.

In a press statement, SunPower notes that it is continuing with its planned acquisition of SolarWorld Americas and its factory in Oregon. The company also notes that this transaction is expected to close before the end of the quarter, which means within the next two weeks.

“SunPower can now fully focus our resources to deliver the best solar solutions to our customers, develop the next wave of solar technology through American research and development and invest in American solar manufacturing,” reads a statement by SunPower Chair and CEO Tom Werner. “This will support U.S. solar technology leadership and preserve American jobs.”

In its announcement that it would acquire the factory, SunPower noted the Trump Administration’s interest in retaining U.S. manufacturing. And while product exemptions are supposed to be made on technical grounds and not as quid-pro-quo arrangements, this would not be the first time the Trump Administration eschewed a norm of governance.

The U.S. Trade Representative also included an exemption for modules made from crystalline silicon solar cells manufactured solely in the United States. However as there are no merchant cell providers in the United States and only a two large factories that produce such cells for their own consumption (SolarWorld Americas and the Panasonic/Tesla Gigafactory in Buffalo), it is unclear to whom this would apply.

Update: This article was updated at 2:52 PM on September 18 to clarify the details of the exemption.