Throughout history, humans have utilized the Sun’s energy in many different ways. From lighting fires, warming houses, and most recently, even to produce electricity to power modern homes and businesses. Historians claim that from as early as 7th century B.C., humans began lighting fires by concentrating the Sun’s light through a magnifying glass. Later around the 3rd century B.C., the Greeks and Romans began utilizing what they called “burning mirrors” to light torches. Early civilizations used the Sun’s energy in architectural design, creating “sunrooms,” which directed sunlight through massive windows for heat and light. In 1767 the first solar oven was invented, a mechanism utilizing sunlight to heat meals or drinks. This technology is still prevalent today in areas of the world that do not have access to electricity. The notion of manipulating the Sun’s energy has been a universal practice across the span of history. More recent events, though, have laid the foundation for booming technologies that we see today, solar photovoltaic panels.
The discovery of the photovoltaic effect and invention of the solar cell
The development of solar technology first began with a young French physicist, Alexander Edmond Becquerel, who discovered the “photovoltaic (P.V.) effect” in 1839. When experimenting with two metal electrodes in an electrolyte solution (a conducting solution,) he observed that when light struck the electrodes, an increase in voltage would occur. This discovery of the photovoltaic effect laid the groundwork of solar technologies to come.
Willoughby Smith, an English electrical engineer, is known for his discovery of the photoconductivity of the element Selenium (atomic #34 on the periodic table) in 1873. In 1876, Professor William Grylls Adams and his student Richard Evans Day proved it possible to convert solar energy directly into electricity using selenium. The first photovoltaic cell, made from Selenium wafers, was produced in 1883 by American inventor Charles Fritts.
A deeper understanding of the photovoltaic effect leads to the modern solar cell design.
Though the cells in modern solar panels are made using crystalline silicon, Fritts is known for creating the ancestor to the solar cells that we use today. However, the process of how light produces electricity was not fully understood until after the 1905 publication of Albert Einstein’s paper on the photoelectric effect. Einstein claimed that light contains packets of energy called photons, and the wavelength could determine the amount of power carried by these photons. This description of light introduced structure to photovoltaics that it previously lacked.
A more practical solar cell made from silicon, invented by three scientists at Bell Labs, Daryl Chapin, Calvin Fuller, and Gerald Pearson, appeared in 1954. The use of silicon provided better efficiency, and it was also widely available as a natural resource in comparison with selenium. Some would say that this marks the real invention of solar cells, as this was the first solar cell that was capable of powering an electric device for several hours. At nearly a quarter of the efficiency of modern solar cells, this first invention was capable of converting sunlight at an efficiency of only 4%!
Other significant events of solar history
- Solar panels in space: With the development of the space age, solar panels were used to power various spacecraft, like satellites. One of the first was Vanguard I satellite in 1958, which used a single-watt solar panel to power radios. In that same year, Vanguard II, Explorer II, and Sputnik-3 all utilized solar technologies. In 1964 NASA’s Nimbus satellite was wholly powered by a 470-watt solar system.
- Oil shortage of the 1970s: During a time of high inflation, it was brought to attention that the U.S. was dependent on foreign energy resources. A deficit for essentials made it evident that we required alternative sources of energy. At this time, President Jimmy Carter had solar panels installed on the roof of the White House. This was an act to spread awareness about clean energy and to make a statement of solar energy being accessible to the people. Later the removal of these panels would be requested by president Ronald Reagan and subsequently asked for reinstallation along with a solar water heater by President Barrack Obama during his first term.
- First Solar Residence: In 1973, the University of Delaware built the first solar building, “Solar One.” The system, designed as a solar P.V./Thermal hybrid, allowed for excess power to be fed into the power grid during the day and utilized during the night.
- Advancements in conversion efficiency: Hoffman electronics are responsible for many breakthroughs in photovoltaic energy, improving the rates from 4% to 14% between 1957 and 1960. In 1985, the University of South Wales advanced this to 20%, and in 1999 the National Renewable Energy Laboratory and SpectroLab Inc. collaborated to produce a solar cell with a 33.3% efficiency rate. By 2016 the record for most efficient solar cell was held again by the University of South Wales at 34.5% efficiency.
- Cost of solar: In 1956, the first solar array became commercially available, however at $300/watt the expense was far beyond the means of civilians. By 1975 the cost had reduced to about $100/watt, and the price has continuously dropped by at least 10% each year. This reduction in cost is the reason for the surge in demand that resulted in over one million solar installations in the U.S. as of 2016.
Solar Power in Today’s World
Research and advancements in solar technologies continue at a vigorous rate in today’s world. With rapid decreases in cost, it has become an increasingly popular source for renewable energy. Although the concept is centuries old, the achievements of the last few decades have notably changed the industry forever. Solar technologies have a compelling history and a promising future!