SunPower is the nation’s No. 2 commercial solar-power company, employing thousands of workers directly and indirectly. But it makes most of its solar panels abroad, and with the tariffs recently imposed by President Trump costing it as much as $2 million a week, SunPower is fighting for an exemption. One of its rivals, SolarWorld Americas, produces panels domestically. Buffeted by foreign competition, it was behind the original push for the tariffs.Now the two American companies are merging.It’s all part of the disruption, distortion and uncertainty from an escalating trade offensive aimed primarily at China. In barely three months, the tariffs — the first shot fired by Mr. Trump in that campaign — are fundamentally reshaping the solar industry and its prospects.A Chinese player announced plans to open a factory in Florida as early as this fall. With its SolarWorld acquisition, SunPower moved to prevent further loss to its business by locating a bigger share of its production in the United States. Both companies are being hit with tariffs on high-efficiency panels they produce in Malaysia.