2022-06-06
"The Birth of Photovoltaics
In 1839, A.E. Becquerel, a 19-year-old French scientist, slowly inserted two platinum electrodes into an acidic solution of silver chloride in his father's laboratory. Unbeknownst to him, the door to the world of photovoltaics was slowly opening with this "wrong" experiment. Measuring the current flowing between these electrodes, he found that the current in the light was slightly higher than the current in the dark; he named this phenomenon the photovoltaic effect. What he did not anticipate was that the small photocurrent he observed in this experiment would bring about a major change in human energy use a century later. In honor of his discovery, the photovoltaic effect is also known as the "Becquerel effect".
After Becquerel's experiments had been dormant for 37 years, British scientist William Grills Adams and his student Richard Evans Day discovered that selenium produces electricity when exposed to light. Although selenium could not provide the electrical energy needed for the electronic components in use at the time, this proved that solid metals could directly convert light into electricity.
In 1883, the American scientist Charles Fritz plated a layer of selenium metal electrode on germanium sheet to establish the first photovoltaic cell. Although it had a conversion efficiency of only 1% and was extremely costly, Fritz was ambitious: "It outputs electricity continuously and steadily, not only in daylight, but also by using scattered light and even dim light...We may soon see photovoltaic panels competing with [coal-fired power plants]! " Unfortunately, his prediction did not come true. He had sent a photovoltaic cell to Siemens, then on par with Edison, who praised his invention. Siemens believed that photovoltaic technology had far-reaching significance in science, and Maxwell, the physics bull of the time, also agreed, as he had made the famous "Maxwell's system of equations" famous in physics. Since then, many scientists have begun to conduct basic research on the photoelectric effect. However, whether it is Siemens or Maxwell, have not been able to crack the secret behind the photovoltaic.
After 24 years of this mystery, a breakthrough was finally achieved by another giant of physics, Albert Einstein, who in 1907 provided a theoretical explanation of the photoelectric effect based on his 1905 quantum hypothesis of the photon. For this, he was awarded the Nobel Prize for Physics in 1921. between 1912 and 1916, the American experimental physicist Robert Andrews Milliken confirmed Einstein's conjecture on the photoelectric effect through experiments and was awarded the Nobel Prize for Physics in 1923. With the solid support of theory, the development of photovoltaics began to enter the fast lane.
In 1916, Polish chemist Jan Czeklarski discovered the crystal-pulling process for purifying monocrystalline silicon, and named it the Czeklarski Method after him. This technology did not begin to be practically applied to the manufacture of wafers in the semiconductor manufacturing industry until the 1950s, and with the increasing demand for large-scale semiconductor devices, this process is constantly evolving.
The wheel of history moved forward almost 20 more years when, in 1934, scientists began research on thin-film solar cells and envisioned creating energy self-sufficient systems through solar cells. Experimental data showed that power generation efficiency could be improved by doping the material with metal impurities.
In 1940, U.S. semiconductor expert Russell Orr created the basic structure of the solid-state diode p-n junction, which laid a solid foundation for the invention and manufacture of solar cells, greatly advancing photovoltaic power generation to the industrial field.
In 1953, the American physicist Daryl Chapin, Gerald Pearson and chemist Calvin Sauser Fowler manufactured crystalline silicon solar cells, each about 2 centimeters in size, with a production efficiency of about 4%. Since then, solar cells have gradually made their way into industry.
Into industry
On March 17, 1958, the second U.S. artificial satellite used chemical and photovoltaic cells, through the launcher into space. This small satellite laid the foundation for the use of solar cells, which have been gradually developed for space exploration ever since. The value of the extended spacecraft life achieved through batteries far outweighs the high cost of solar cell manufacturing. In addition, solar cells have become cheaper and less risky than radioisotope generators. Today, most spacecraft are equipped with solar cells, and about 1,000 satellites in the world are using photovoltaics to generate electricity. In space, solar cells achieve an output of 220 watts per square meter.
In 1976, the Australian government decided to operate the entire telecommunications network in the outback through photovoltaic cell stations. The establishment and operation of photovoltaic power stations was so successful that it raised confidence in solar technology worldwide.
Since 1980, small unmanned oil drilling platforms in the Gulf of Mexico have been equipped with solar modules and have gradually replaced the large batteries previously used with the advantages of economy and practicality.
Since 1983, the U.S. Coast Guard began to use photovoltaic for its signal lights and navigation lights power supply. At this time, the U.S. share of the global photovoltaic market was about 21%, and the PV market was mainly for stand-alone system solutions.
Since 1990, the Swiss engineer Markus Real has suggested that it makes more economic sense to equip each house with its own photovoltaic system, i.e. to support decentralized energy conversion. He installed 333 3 kW rooftop PV systems in individual buildings in Zurich.
In 1991, Germany launched the 1,000 Roofs program, and the "Feed-in Law" made it mandatory for utility companies to obtain electricity from small renewable energy plants. Solon AG in Berlin and a solar plant in Freiburg were established.
In 1994 and 1997, Japan and the United States launched the Million Roof Program.
In 2010, the total rated power of photovoltaic systems in Germany exceeded 10 gigawatts, and in 2015, the rated power of photovoltaic systems worldwide reached 200 gigawatts.
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