A 19-year-old built the first solar cell in his father's lab
In 1839, Edmond Becquerel, then just nineteen, showed in his father's Paris laboratory that light could produce electricity. It took more than a century for the effect to become useful, and space, not rooftops, was where solar cells first proved themselves: satellites wanted the best power for the least weight.
Understanding came slowly. Willoughby Smith reported in Nature in 1873 that light changed how selenium conducted electricity, and three years later William Grylls Adams and Richard Evans Day made the first solid-state photovoltaic cell. Albert Einstein's 1905 quantum explanation of the photoelectric effect earned him the 1921 Nobel Prize in Physics. Russell Ohl patented the modern junction cell in 1946 during research that also led toward the transistor, and Bell Laboratories publicly demonstrated a practical silicon cell in 1954.
Orbit gave the technology its first big job. Vanguard I carried solar cells in 1958 as a backup to its batteries, stretching the mission without redesigning the craft. The next year Explorer 6 flew with wing-shaped arrays built from 9,600 Hoffman cells, a layout that became standard. Because satellite builders would pay for the very best cells, there was little incentive to make cheap ones, and prices fell only gradually through the 1960s. In the early 1990s space cells split from rooftop technology, moving to gallium arsenide and then multi-junction cells that stack layers tuned to different parts of the solar spectrum.
Back on the ground, the question became cost. In 1973 Elliot Berman set up Solar Power Corporation as an Exxon subsidiary, convinced that electricity would grow expensive and that a price near $20 per watt would unlock demand. By 2020, utility-scale systems in the United States cost about $0.94 per watt. Crystalline silicon now makes up around 95 percent of commercial cells, with cadmium telluride thin film covering the rest.
Each cell must do three things: absorb light, separate the resulting positive and negative charges, and deliver them to a circuit. A single silicon cell yields only about half a volt, so cells are wired in series to raise voltage and in parallel to raise current. Shade on one cell can drag down a whole string, which is why panels include bypass diodes. Solar cars are older than many assume; the first World Solar Challenge, a 3,000-kilometre race across the Australian outback organised by Hans Tholstrup in 1987, was won by General Motors' Sunraycer.
Source: Solar cell
