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Solar cell: the story on HearLore | HearLore
Solar cell
In 1839, a nineteen-year-old French physicist named Edmond Becquerel discovered that light could generate electricity, creating the world's first photovoltaic cell in his father's laboratory. This was not a device that could power a city, but a small glass cell that produced a tiny current when exposed to light. For decades, this phenomenon remained a scientific curiosity, a laboratory oddity that failed to find practical application. It was not until 1883 that Charles Fritts attempted to build the first solid-state photovoltaic cell by coating selenium with a thin layer of gold. The result was a device with an efficiency of only one percent, barely enough to register on a meter, yet it proved the concept was real. The world waited another century for the technology to mature, while scientists like Willoughby Smith and Heinrich Hertz continued to map the boundaries of the photoelectric effect. By 1905, Albert Einstein would explain the underlying quantum theory of light, a breakthrough that would eventually earn him the Nobel Prize in Physics in 1921, but the practical device remained elusive. The path from a curious observation in a French laboratory to a global energy revolution was long, winding, and filled with dead ends before the first practical cell ever appeared.
The Space Race and Silicon
The first practical photovoltaic cell was publicly demonstrated at Bell Laboratories on the 25th of April 1954 by inventors Calvin Souther Fuller, Daryl Chapin, and Gerald Pearson. This device, made of silicon, achieved an efficiency of six percent, a massive leap from the one percent of Fritts' selenium cell, and it marked the birth of the modern solar age. However, the true catalyst for solar technology was not the Earth, but the sky. In 1958, the United States launched the Vanguard 1 satellite, the first spacecraft to use solar cells as its primary power source, extending its mission life indefinitely compared to battery-powered predecessors. By 1959, Explorer 6 carried 9,600 Hoffman solar cells in large wing-shaped arrays, establishing solar power as the standard for space exploration. The space program drove the development of higher efficiencies because there were no other options for long-duration missions, forcing engineers to perfect the technology. This success created a unique market where cost was secondary to performance, allowing researchers to develop cells that were far too expensive for terrestrial use. It was not until the National Science Foundation's Research Applied to National Needs program began in 1969 that the focus shifted to making solar power affordable for the ground. The transition from space to Earth required a complete rethinking of manufacturing, moving from expensive, hand-wired space cells to cheaper, mass-produced terrestrial panels.
Who discovered the first photovoltaic cell and when did this happen?
Edmond Becquerel discovered the first photovoltaic cell in 1839 while working in his father's laboratory. This discovery created the world's first photovoltaic cell that produced a tiny current when exposed to light.
When was the first practical photovoltaic cell publicly demonstrated and by whom?
The first practical photovoltaic cell was publicly demonstrated at Bell Laboratories on the 25th of April 1954 by inventors Calvin Souther Fuller, Daryl Chapin, and Gerald Pearson. This silicon device achieved an efficiency of six percent and marked the birth of the modern solar age.
What year did the United States launch the first spacecraft to use solar cells as its primary power source?
The United States launched the Vanguard 1 satellite in 1958 as the first spacecraft to use solar cells as its primary power source. This mission extended the spacecraft's life indefinitely compared to battery-powered predecessors and established solar power as the standard for space exploration.
How much did the price of solar modules drop from the mid-1970s to 2018?
The price of solar modules in the mid-1970s was approximately ninety-six dollars per watt and dropped by more than ninety-nine percent to thirty cents per watt by 2018. This dramatic cost reduction was driven by Swanson's Law which states that solar cell prices fall twenty percent for every doubling of industry capacity.
What percentage of the commercial solar cell market does crystalline silicon account for today?
Crystalline silicon accounts for ninety-five percent of the commercial solar cell market today. These cells are made from wafers that are between 160 and 240 micrometers thick and cut from cylindrical ingots grown by the Czochralski process.
Which country controls the majority of the global solar supply chain as of 2023?
China controls over 80 percent of all manufacturing stages for solar panels and maintained a dominant market share of 77.8 percent as the world's largest PV module producer in 2022. In the first half of 2023, China's production of PV modules exceeded 220 gigawatts marking an increase of over 62 percent compared to the same period in 2022.
In late 1969, Elliot Berman joined Exxon's task force to find energy solutions for the future, and by April 1973, he founded Solar Power Corporation, a subsidiary dedicated to making solar power affordable. The team concluded that electrical power would be much more expensive by the year 2000, and they set a target price of twenty dollars per watt to create significant demand. To achieve this, they eliminated the expensive steps of polishing wafers and applying anti-reflective coatings, relying instead on rough-sawn surfaces and printed circuit boards. They replaced the hand-wiring used in space applications with acrylic plastic and silicone glue, potting the cells to protect them from the elements. By 1973, they announced a product that convinced Tideland Signal to use its panels to power navigational buoys for the U.S. Coast Guard. The 1973 oil crisis triggered a wave of investment from major oil companies like Exxon, ARCO, Shell, and Mobil, who all established solar divisions to capitalize on the new energy landscape. The price of solar modules in the mid-1970s was approximately ninety-six dollars per watt, a figure that would eventually drop by more than ninety-nine percent to thirty cents per watt by 2018. This dramatic cost reduction was driven by Swanson's Law, which states that solar cell prices fall twenty percent for every doubling of industry capacity, a phenomenon similar to Moore's Law for computer chips. The shift from a niche space technology to a global commodity was complete, but it required decades of industrial scaling and policy support to reach grid parity.
The Silicon Dominance
Crystalline silicon remains the dominant material for solar cells, accounting for ninety-five percent of the commercial market today. These cells are made from wafers that are between 160 and 240 micrometers thick, cut from cylindrical ingots grown by the Czochralski process. Monocrystalline silicon cells feature a single-crystal composition that allows electrons to move more freely, delivering higher efficiency than their multicrystalline counterparts. The corners of these cells are clipped to form an octagon, a distinctive visual signature of the manufacturing process. Polycrystalline silicon, or multicrystalline silicon, is made from cast square ingots that are cooled and solidified to create small crystals, giving the material a metal flake effect. While less efficient than monocrystalline silicon, polysilicon cells are less expensive and dominate the low-cost panel market. The industry has seen a shift in wafer sizes, with panels in the 1990s and early 2000s generally using 125 millimeter wafers, and since 2008, almost all new panels using greater than 156 millimeter cells. By 2020, even larger 182 millimeter M10 cells became the standard, driven by the availability of large, high-quality glass sheets from the flat screen television industry. The efficiency of single p-n junction crystalline silicon devices is now approaching the theoretical Shockley-Queisser limit of 33.16 percent, a barrier that has taken decades to approach. Despite the dominance of silicon, other materials like cadmium telluride and copper indium gallium selenide have found niches in thin-film applications, but they remain secondary to the silicon revolution.
The Future of Light
The next generation of solar technology is moving beyond silicon, with perovskite solar cells emerging as a rapidly advancing field. Since their first usage in 2009, efficiencies have increased from below five percent to 25.5 percent in 2020, making them a hot topic in the solar cell field. Researchers at the University of Rochester reported in 2023 that significant further improvements can be achieved by utilizing the Purcell effect, while other teams are working to solve the operational stability issues that have prevented commercialization. Bifacial solar cells, which can absorb light from both the front and rear sides, offer a potential 50 percent increase in output power when paired with a white background, and are expected to expand from less than five percent of the market in 2016 to 30 percent in 2027. Quantum dot solar cells and organic polymer cells are also being developed, offering the possibility of flexible, lightweight, and transparent panels that can be applied to windows, sails, and drone wings. In 2022, MIT researchers developed ultralight fabric solar cells that weigh one-hundredth that of traditional panels while generating 18 times more power per kilogram. These cells, thinner than a human hair, can be laminated onto various surfaces, extending the functionality of existing structures. The future of solar energy is not just about efficiency, but about integration, flexibility, and the ability to turn any surface into a power source.
The Global Power Shift
China has emerged as the dominant force in the global solar supply chain, controlling over 80 percent of all manufacturing stages for solar panels. As of September 2018, sixty percent of the world's solar photovoltaic modules were made in China, and by 2022, China maintained its position as the world's largest PV module producer, holding a dominant market share of 77.8 percent. In the first half of 2023, China's production of PV modules exceeded 220 gigawatts, marking an increase of over 62 percent compared to the same period in 2022. This dominance has drastically cut costs, but it has also led to issues like supply-demand imbalances and polysilicon production constraints. The largest photovoltaic plant in the world is located in the Tengger desert in China, and in 2018, China added more photovoltaic installed capacity than the next nine countries combined. Other key producers include Vietnam, which was the second-largest PV module producer in 2022 with a production capacity of 24.1 gigawatts, and Malaysia, which was the third-largest with 10.8 gigawatts. The strategic policies of China have reduced solar PV costs by more than 80 percent, increasing global affordability, but the concentration of production poses risks of supply shortages and cost surges. The global energy and climate targets necessitate a major expansion in solar PV manufacturing, aiming for over 630 gigawatts by 2030, with China playing a central role in meeting these goals.