A LED solar simulator to test panels at a Hanwha Qcells testing site in Bitterfeld-Wolfen, Germany, Sept. 24, 2026. At its lab in Germany, Hanwha Qcells has been testing its tandem solar panels, a new technology that solar companies say will generate more energy. (Patrick Junker/The New York Times) By IVAN PENN Producers of solar panels in the United States say they are on the cusp of a technological breakthrough that could upend the industry and even threaten China’s grip on it. The…
