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. 美国太阳能板生产商表示，他们即将迎来一项技术突破，这项突破可能颠覆整个行业，甚至威胁到中国在该行业的垄断地位。 The manufacturers are racing…