Bruno Lange

Bruno Lange was a German engineer who built one of the first practical photoelectric solar cells, using silver selenide in place of the copper oxide used in earlier selenium photocells. His 1931 solar cell converted less than one percent of incident sunlight into electricity, far too little for practical power generation, but Lange was an outspoken early visionary for the technology's potential, predicting that vast fields of such cells would one day generate electricity competitive with hydroelectric and steam power stations. His cell design, marketed commercially as the Photox cell by Westinghouse in the 1930s, found practical use in light-measuring instruments such as photographic exposure meters rather than in power generation, since silicon-based photovoltaic cells with far higher efficiency were not developed until decades later. Lange's work is remembered in the history of solar technology as one of the earliest serious engineering attempts, however limited in output, to turn sunlight directly into usable electric current.