Short answers, pulled from the story.
A solar cell, also known as a photovoltaic cell, is an electronic device that converts light directly into electricity using the photovoltaic effect. When photons strike a semiconductor material such as silicon, they excite electrons across a p-n junction, generating an electrical current. The common single-junction silicon solar cell produces a maximum open-circuit voltage of approximately 0.5 to 0.6 volts.
French physicist Edmond Becquerel built the world's first photovoltaic cell in 1839 at age 19, in his father's laboratory. The first practical photovoltaic cell was publicly demonstrated at Bell Laboratories in 1954 by inventors Calvin Souther Fuller, Daryl Chapin, and Gerald Pearson.
Solar cells were first used in a prominent space application in 1958, when they were added to the Vanguard satellite as an alternative power source alongside its primary batteries. In 1959, the United States launched Explorer 6 with large wing-shaped solar arrays consisting of 9,600 Hoffman solar cells.
Adjusted for inflation, a solar module cost approximately $96 per watt in the mid-1970s. By 2020 that figure had fallen to as low as 20 cents per watt, a decline of more than 99%. Costs of solar photovoltaic electricity fell by roughly 85% between 2010 and 2021.
In 2022, researchers at the Fraunhofer Institute for Solar Energy Systems in Freiburg, Germany demonstrated a four-junction concentrator solar cell reaching 47.6% efficiency under 665-fold sunlight concentration. For a single-junction solar cell, gallium arsenide holds the world record at 28.8%.
China is the dominant solar panel producer. In 2022, China held a market share of 77.8% of global PV module production. The IEA reports that China controls over 80% of all manufacturing stages for solar panels and has invested more than US$50 billion in the sector since 2011, creating around 300,000 jobs.