Solar Cell
Photovoltaic solar cells are thin silicon disks that convert sunlight into electricity. These disks act as energy sources for a wide variety of uses, including: calculators and other small devices; telecommunications; rooftop panels on individual houses; and for lighting, pumping, and medical refrigeration for villages in developing countries. Solar cells in the form of large arrays are used to power satellites and, in rare cases, to provide electricity for power plants.
When research into electricity began and simple batteries were being made and studied, research into solar electricity followed amazingly quickly. As early as 1839, Antoine-Cesar Becquerel exposed a chemical battery to the sun to see it produce voltage. This first conversion of sunlight to electricity was one percent efficient. That is, one percent of the incoming sunlight was converted into electricity. Willoughby Smith in 1873 discovered that selenium was sensitive to light; in 1877 Adams and Day noted that selenium, when exposed to light, produced an electrical current. Charles Fritts, in the 1880s, also used gold-coated selenium to make the first solar cell, again only one percent efficient. Nevertheless, Fritts considered his cells to be revolutionary. He envisioned free solar energy to be a means of decentralization, predicting that solar cells would replace power plants with individually powered residences.
With Albert Einstein’s explanation in 1905 of the photoelectric effect—metal absorbs energy from light and will retain that energy until too much light hits it—hope soared anew that solar electricity at higher efficiencies would become feasible. Little progress was made, however, until research into diodes and transistors yielded the knowledge necessary for Bell scientists Gordon Pearson, Darryl Chapin, and Cal Fuller to produce a silicon solar cell of four percent efficiency in 1954.
Further work brought the cell’s efficiency up to 15 percent. Solar cells were first used in the rural and isolated city of Americus, Georgia as a power source for a telephone relay system, where it was used successfully for many years.
A type of solar cell to fully meet domestic energy needs has not as yet been developed, but solar cells have become successful in providing energy for artificial satellites. Fuel systems and regular batteries were too heavy in a program where every ounce mattered. Solar cells provide more energy per ounce of weight than all other conventional energy sources, and they are cost-effective.
Only a few large scale photovoltaic power systems have been set up. Most efforts lean toward providing solar cell technology to remote places that have no other means of sophisticated power. About 50 megawatts are installed each year, yet solar cells provide only about. 1 percent of all electricity now being produced. Supporters of solar energy claim that the amount of solar radiation reaching the Earth’s surface each year could easily provide all our energy needs several times over, yet solar cells have a long way to go before they fulfill Charles Fritts’s dream of free, fully accessible solar electricity.
Raw Materials
The basic component of a solar cell is pure silicon, which is not pure in its natural state.
To make solar cells, the raw materials—silicon dioxide of either quartzite gravel or crushed quartz—are first placed into an electric arc furnace, where a carbon arc is applied to release the oxygen. The products are carbon dioxide and molten silicon. At this point, the silicon is still not pure enough to be used for solor cells and requires further purification.
Pure silicon is derived from such silicon dioxides as quartzite gravel (the purest silica) or crushed quartz. The resulting pure silicon is then doped (treated with) with phosphorous and boron to produce an excess of electrons and a deficiency of electrons respectively to make a semiconductor capable of conducting electricity. The silicon disks are shiny and require an anti-reflective coating, usually titanium dioxide.
The solar module consists of the silicon semiconductor surrounded by protective material in a metal frame. The protective material consists of an encapsulant of transparent silicon rubber or butyryl plastic (commonly used in automobile windshields) bonded around the cells, which are then embedded in ethylene vinyl acetate. A polyester film (such as mylar or tedlar) makes up the backing. A glass cover is found on terrestrial arrays, a lightweight plastic cover on satellite arrays. The electronic parts are standard and consist mostly of copper. The frame is either steel or aluminum. Silicon is used as the cement to put it all together.
The Manufacturing Process
Purifying the silicon
- 1 The silicon dioxide of either quartzite gravel or crushed quartz is placed into an electric arc furnace. A carbon arc is then applied to release the oxygen. The products are carbon dioxide and molten silicon. This simple process yields silicon with one percent impurity, useful in many industries but not the solar cell industry.
- 2 The 99 percent pure silicon is purified even further using the floating zone technique. A rod of impure silicon is passed through a heated zone several times in the same direction. This procedure drags the impurities toward one end with each pass. At a specific point, the silicon is deemed pure, and the impure end is removed.
Making single crystal silicon
- 3 Solar cells are made from silicon boules, polycrystalline structures that have the atomic structure of a single crystal. The most commonly used process for creating the boule is called the Czochralski method. In this process, a seed crystal of silicon is dipped into melted polycrystalline silicon. As the seed crystal is withdrawn and rotated, a cylindrical ingot or boule of silicon is formed. The ingot withdrawn is unusually pure, because impurities tend to remain in the liquid.
Making silicon wafers
- 4 From the boule, silicon wafers are sliced one at a time using a circular saw whose inner diameter cuts into the rod, or many at once with a multiwire saw. (A diamond saw produces cuts that are as wide as the wafer- 5 millimeter thick.) Only about one-half of the silicon is lost from the boule to the finished circular wafer—more if the wafer is then cut to be rectangular or hexagonal. Rectangular or hexagonal wafers are sometimes used in solar cells because they can be fitted together perfectly, thereby utilizing all available space on the front surface of the solar cell.
After the initial purification, the silicon is further refined in a floating zone process. In this process, a silicon rod is passed through a heated zone several times, which serves to ‘drag the impurities toward one end of the rod. The impure end can then be removed. Next, a silicon seed crystal is put into a Czochralski growth apparatus, where it is dipped into melted polycrystalline silicon. The seed crystal rotates as it is withdrawn, forming a cylindrical ingot of very pure silicon. Wafers are then sliced out of the ingot.
Doping
- 6 The traditional way of doping (adding impurities to) silicon wafers with boron and phosphorous is to introduce a small amount of boron during the Czochralski process in step #3 above. The wafers are then sealed back to back and placed in a furnace to be heated to slightly below the melting point of silicon (2,570 degrees Fahrenheit or 1,410 degrees Celsius) in the presence of phosphorous gas. The phosphorous atoms burrow into the silicon, which is more porous because it is close to becoming a liquid. The temperature and time given to the process is carefully controlled to ensure a uniform junction of proper depth. A more recent way of doping silicon with phosphorous is to use a small particle accelerator to shoot phosphorous ions into the ingot. By controlling the speed of the ions, it is possible to control their penetrating depth. This new process, however, has generally not been accepted by commercial manufacturers.
Placing electrical contacts
- 7 Electrical contacts connect each solar cell to another and to the receiver of produced current. The contacts must be very thin (at least in the front) so as not to block sunlight to the cell. Metals such as palladium/silver, nickel, or copper are vacuum-evaporated
This illustration shows the makeup of a typical solar cell. The cells are encapsulated in ethylene vinyl acetate and placed in a metal frame that has a mylar backsheet and glass cover.
The anti-reflective coating
- 9 Because pure silicon is shiny, it can reflect up to 35 percent of the sunlight. To reduce the amount of sunlight lost, an anti-reflective coating is put on the silicon wafer. The most commonly used coatings are titanium dioxide and silicon oxide, though others are used. The material used for coating is either heated until its molecules boil off and travel to the silicon and condense, or the material undergoes sputtering. In this process, a high voltage knocks molecules off the material and deposits them onto the silicon at the opposite electrode. Yet another method is to allow the silicon itself to react with oxygen- or nitrogen-containing gases to form silicon dioxide or silicon nitride. Commercial solar cell manufacturers use silicon nitride.
Encapsulating the cell
- 10 The finished solar cells are then encapsulated; that is, sealed into silicon rubber or ethylene vinyl acetate. The encapsulated solar cells are then placed into an aluminum frame that has a mylar or tedlar backsheet and a glass or plastic cover.
Quality Control
Quality control is important in solar cell manufacture because discrepancy in the many processes and factors can adversely affect the overall efficiency of the cells. The primary research goal is to find ways to improve the efficiency of each solar cell over a longer lifetime. The Low Cost Solar Array Project (initiated by the United States Department of Energy in the late 1970s) sponsored private research that aimed to lower the cost of solar cells. The silicon itself is tested for purity, crystal orientation, and resistivity. Manufacturers also test for the presence of oxygen (which affects its strength and resistance to warp) and carbon (which causes defects). Finished silicon disks are inspected for any damage, flaking, or bending that might have occurred during sawing, polishing, and etching.
During the entire silicon disk manufacturing process, the temperature, pressure, speed, and quantities of dopants are continuously monitored. Steps are also taken to ensure that impurities in the air and on working surfaces are kept to a minimum.
The completed semiconductors must then undergo electrical tests to see that the current, voltage, and resistance for each meet appropriate standards. An earlier problem with solar cells was a tendency to stop working when partially shaded. This problem has been alleviated by providing shunt diodes that reduce dangerously high voltages to the cell. Shunt resistance must then be tested using partially shaded junctions.
An important test of solar modules involves providing test cells with conditions and intensity of light that they will encounter under normal conditions and then checking to see that they perform well. The cells are also exposed to heat and cold and tested against vibration, twisting, and hail.
The final test for solar modules is field site testing, in which finished modules are placed where they will actually be used. This provides the researcher with the best data for determining the efficiency of a solar cell under ambient conditions and the solar cell’s effective lifetime, the most important factors of all.
The Future
Considering the present state of relatively expensive, inefficient solar cells, the future can only improve. Some experts predict it will be a billion-dollar industry by the year 2000. This prediction is supported by evidence of more rooftop photovoltaic systems being developed in such countries as Japan, Germany, and Italy. Plans to begin the manufacture of solar cells have been established in Mexico and China. Likewise, Egypt, Botswana, and the Philippines (all three assisted by American companies) are building plants that will manufacture solar cells.
Most current research aims for reducing solar cell cost or increasing efficiency. Innovations in solar cell technology include developing and manufacturing cheaper alternatives to the expensive crystalline silicon cells. These alternatives include solar Windows that mimic photosynthesis, and smaller cells made from tiny, amorphous silicon balls. Already, amorphous silicon and polycrystalline silicon are gaining popularity at the expense of single crystal silicon. Additional innovations including minimizing shade and focusing sunlight through prismatic lenses. This involves layers of different materials (notably, gallium arsenide and silicon) that absorb light at different frequencies, thereby increasing the amount of sunlight effectively used for electricity production.
A few experts foresee the adaptation of hybrid houses; that is, houses that utilize solar water heaters, passive solar heating, and solar cells for reduced energy needs. Another view concerns the space shuttle placing more and more solar arrays into orbit, a solar power satellite that beams power to Earth solar array farms, and even a space colony that will manufacture solar arrays to be used on Earth.
Where To Learn
Books
Bullock, Charles E. and Peter H. Grambs. Solar Electricity: Making the Sun Work for You. Monegon, Ltd., 1981.
Komp, Richard J. Practical Photovoltaics. Aatec Publications, 1984.
Making and Using Electricity from the Sun. Tab Books, 1979.
Periodicals
Crawford, Mark. DOE’s Born-Again Solar Energy Plan, Science. March 23, 1990, pp. 1403-1404.
Waiting for the Sunrise, Economist. May 19, 1990, pp. 95.
Edelson, Edward. Solar Cell Update, Popular Science. June, 1992, p. 95.
Murray, Charles J. Solar Power’s Bright Hope, Design News. March 11, 1991, p. 30.
History and Definition of a Solar Cell
Mary Bellis covered inventions and inventors for ThoughtCo for 18 years. She is known for her independent films and documentaries, including one about Alexander Graham Bell.
Any device that directly converts the energy in light into electrical energy through the process of photovoltaics is a solar cell. The development of solar cell technology begins with the 1839 research of French physicist Antoine-César Becquerel. Becquerel observed the photovoltaic effect while experimenting with a solid electrode in an electrolyte solution when he saw a voltage develop when the light fell upon the electrode.
Charles Fritts. First Solar Cell
According to Encyclopedia Britannica, the first genuine solar cell was built around 1883 by Charles Fritts, who used junctions formed by coating selenium (a semiconductor) with an extremely thin layer of gold.
Russell Ohl. Silicon Solar Cell
Early solar cells, however, had energy conversion efficiencies of under one percent. In 1941, the silicon solar cell was invented by Russell Ohl.
Gerald Pearson, Calvin Fuller, and Daryl Chapin. Efficient Solar Cells
In 1954, three American researchers, Gerald Pearson, Calvin Fuller, and Daryl Chapin, designed a silicon solar cell capable of a six percent energy conversion efficiency with direct sunlight.
The three inventors created an array of several strips of silicon (each about the size of a razor blade), placed them in sunlight, captured the free electrons and turned them into electrical current. They created the first solar panels. Bell Laboratories in New York announced the prototype manufacture of a new solar battery. Bell had funded the research. The first public service trial of the Bell Solar Battery began with a telephone carrier system (Americus, Georgia) on October 4, 1955.
Partnership Spans Eras, Proves Cadmium Telluride Modules Stable, Efficient, Reliable, Cost Competitive
The National Renewable Energy Laboratory (NREL) has more than 550 unique, active partners. One such partner is First Solar Inc.—a relationship that dates back to the early ‘90s. NREL and First Solar, then called Solar Cells Inc., have been collaboratively breaking ground on thin film solar technology for more than two decades, helping NREL fulfill its goal as a Department of Energy (DOE) national laboratory of commercializing technology through partnerships, and contributing to First Solar’s success in development, manufacturing, and operation of photovoltaic (PV) power plants with technology that still bucks industry trends.
In early July, First Solar made headlines when it announced its intention to construct a 680 million solar panel manufacturing factory in Ohio, bringing with it an estimated 500 jobs. The announcement came just seven months into the inaugural year of the Biden administration, whose intersecting priorities to “build a modern, sustainable infrastructure and an equitable clean energy future” and “ensure the future is ‘made in all of America’ by all of America’s workers” have been well supported by Secretary of Energy Jennifer Granholm.
NREL is on the job, working consistently to enable such a future for nearly 45 years. When Solar Cells Inc. came along in the early ‘90s, the collaboration centered around the reliability, stability, and efficiency of the thin film cadmium telluride (“CdTe” for short) technology that it was using in its solar panels, also called modules. Then and now, the vast majority of solar modules are of crystalline silicon construction instead of cadmium telluride.
The Early Days of the NREL–First Solar Partnership
In 1991, NREL was designated a national laboratory by President George Bush and renamed from its original title, the Solar Energy Research Institute. It was a different time, and unique approaches were taken with research related to CdTe technology.
NREL Group Manager of Materials Reliability and Durability Teresa Barnes said, “in those early times, it was scrappy little startup companies and it was a bunch of old friends working together. The CdTe community has always been very, very small. It was primarily in the U.S., and it was a much smaller research community than any other solar technology that I’ve ever worked in.”
Larry Kazmerski, a retired NREL senior scientist who headed materials and characterization for solar research at NREL at the time, said, for the duration of his time working on Solar Cells Inc. projects, there was never a nondisclosure agreement in place. It was just trust.
“You have to realize they didn’t come to NREL and say, ‘Hey we have a problem. Can you solve it?’” he said. “They would bring people out, and there would be discussion, and people would be looking at it in the lab together. It was a fairly open policy. They could come in and work together without much of a problem.”
Kazmerski saw a larger dependence on NREL, especially in the solar PV area with DOE, industries, and universities. It was more of a partnership of all players. During his time at NREL, Kazmerski recalled two NREL researchers who played key roles in moving CdTe research forward. One was Tom Surek, who pushed university, industry, and national laboratory partnerships, and who Kazmerski called the kingpin of the PV program management side. The other was Ken Zweibel, who brought his physics degree to the program management side of the house and was key in selling the laboratory on the value of CdTe. Kazmerski said they were blessed with program managers who were highly technical.
Reliability of CdTe solar cells was critical early on. Kazmerski said First Solar did not want to release anything until it was ready. They knew they had to have reliable modules. They tested everything to death and worked with NREL to validate efficiency and reliability. Barnes said First Solar is one of the best in the business for understanding reliability and durability, and NREL has learned a lot from the partnership and how it affects product development.
In fact, NREL is still learning from that early success today, thanks to one especially noteworthy achievement that planted roots two and a half decades ago. Twenty-five years ago, NREL installed a 0.6 kW Solar Cells Inc. PV system with 12 modules for a long-term test at the Outdoor Testing Facility. Those modules are still operating today.
Dirk Jordan, a senior engineer at NREL who studies the long-term performance of PV systems and analyzes the physics and chemistry of changes, said, “it’s the longest running system we have. It showed the degradation of a pretty reasonable 0.5% per year, which is in line with what silicon systems do.”
A Few Key Milestones in the Journey
NREL and First Solar have crossed a series of thresholds together and hit numerous milestones along the way. NREL Director of the Power Systems Engineering Center Ben Kroposki said producing a CdTe cell that converted light to electricity with 10% efficiency was a major accomplishment Further research and development has led to today’s CdTe solar cells with efficiencies above 20%.
“When they were first coming out, they did not have very high-efficiency modules, but in working with them—and this was pretty early on—they always had a good idea of how to mass produce panels where they were basically making glass and depositing the CdTe on the glass,” he said. “They had a breakthrough working with some of the materials people at NREL that pushed efficiencies over 10%. That’s one of the big milestones: once they crossed over 10% efficiency and could start mass producing using their production techniques. That was a game-changer for these large-scale systems.”
Scalability has always set the First Solar partnership apart. A partnership goes two ways and where NREL was able to help test, validate, and provide fundamental research for First Solar, First Solar was able to teach NREL a thing or two as well.
“I think First Solar is always our example of how important it is to have a really manufacturable, scalable, steady process and to the importance of reproducibility,” Barnes said. “Because they got so good at scaling those results as they came through, they can now take that latest and greatest and scale it very quickly. For us, it was learning the lesson of not just going for that one, record cell, but understanding what the manufacturable technology limits are and having a process window that’s big enough to actually work with.”
Matt Reese, an NREL senior scientist and CdTe lead, recalled when, several years ago, the NREL group wanted to identify the sources of voltage loss in CdTe cells compared with competing technologies. The group developed experimental models and determined the problem was coming from the copper used to dope the CdTe cells. “Copper moves around a lot and is one of the biggest causes of instability and limits the efficiency,” Reese said.
First Solar found out NREL was working on this, and told NREL they would like the research to be conducted as precompetitive, meaning it would be done much more openly and for the purpose of developing new commercially applicable technologies.
“It turned out we were able—for the first time and using single crystals—instead of getting 0.85 volts, we were able to get out more than a volt,” Reese said. “We understood what was wrong with the system. Once we had this demonstration, First Solar was very excited and started working on its copper replacement process.”
Nature Energy published a paper on crossing the 1-volt barrier with single crystals. Three years later, NREL and First Solar published a paper together, again in Nature Energy, showing that manufacturable thin-film CdTe devices doped with arsenic have efficiencies on par with copper (Cu)-doped devices and a much lower long-term degradation rate. This new technology, called “CuRe” (Cu Replacement), is currently being implemented in First Solar manufacturing lines, paving the way for CdTe cells to become even more efficient and reliable.
Through the years, as technology has advanced, First Solar has occasionally licensed NREL-developed technology, the earliest on record coming in 2007. Reese said having First Solar succeed is a win and it means they are doing something right. Kazmerski noted from the early days how those at NREL also felt any success from industry reflected well on them.
NREL and First Solar continue to work together closely. “NREL recently designed and built a successful vapor transport deposition tool like the one used by First Solar to deposit CdTe films,” said David Albin, another lead CdTe researcher at NREL. “This increases the relevancy of NREL’s work for First Solar. In addition to a long-standing Cooperative Research and Development Agreement (CRADA), we have recently partnered with them in two different cost-share projects that are studying the compatibility of NREL intellectual property with their process.”
Gang Xiong, director of the First Solar California Technology Center, has witnessed the NREL–First Solar collaboration on CdTe research for a decade. “The collaboration is fruitful as we can leverage the complimentary strength of both parties to advance the CdTe solar cell technology together,” he said.
“This partnership truly does add up to more than the sum of its parts. First Solar is really good at screening innovative ideas rapidly and driving toward perfection in our RD labs and our manufacturing lines. NREL is a great source of idea generation, and they have a lot of expertise in characterizing and understanding material/device performance-related issues. We openly share our RD priorities with each other.”
How NREL and First Solar Helped Shape the Solar Industry
The significance of the partnership and the work jointly produced has had an impact on the solar industry beyond simply taking the last survivor of the initial wave of early CdTe companies to the top. It has established a blueprint for introducing and scaling up new technologies and helped push the boundaries and test the limits of what’s possible.
“We have a market of silicon that is always changing and improving and of course CdTe,” Kazmerski said. “If it wasn’t for CdTe, maybe we wouldn’t even be looking at perovskites now. People started to look for alternative thin films that are better. These guys are always keeping on top of things to see if they can’t themselves come into this and be a player or find out what the competition is doing. First Solar is here to stay with their CdTe, but they have shown that a thin film can be very, very competitive. The perovskite people are starting to mimic what First Solar did to show that these modules are really stable.”
Kroposki said First Solar got out in front of another emerging trend as well.
“Early on in the game, they decided to implement full-scale recycling, so they really understand the process end-to-end,” he said. “Only now are the crystalline manufacturers realizing they have to get into this recycling game and start to think about that.”
Barnes acknowledged the success of First Solar and called attention to the importance of having some healthy competition. She also said the fact that they are one of the few U.S. companies still in the business is also important, but First Solar has been looking to advance CdTe technology beyond just what it is using in its modules.
In March 2021, after a series of workshops begun in 2017, Colorado State University, the University of Toledo, NREL, and Tempe, Arizona-headquartered First Solar kicked off an alliance called the U.S. Manufacturing of Advanced Cadmium Telluride (US-MAC) photovoltaics consortium, designed “To further reinforce U.S. leadership in solar technology.”
The press release from the University of Toledo read, “US-MAC will work with its members to advance foundational science and engineering, stimulate innovation, and capitalize on shared resources and expertise. It aims to support increased production volume, optimize performance, and to diversify, integrate, and support the success of domestic firms.” US-MAC includes a total of 10 industry partners (including First Solar) interested in furthering the success of CdTe PV.
“This partnership is one of the best examples of why the lab was set up originally and why it was developed as it was,” Kazmerski said. “It showed that the lab could really help a U.S. industry.”
Who Invented Solar Panels, When, and for What? The Surprising History of Solar
Solar panel technology has evolved over many centuries, but who invented solar panels and who was the first person to harness the sun’s energy to generate electricity?
Solar panels are a remarkable invention and are becoming vital in homes, businesses, and transportation as the world moves away from fossil energy associated with environmental pollution.
But, since static electricity was ‘discovered’ in 600 B.C., how did we get to the point where we can charge an electric vehicle using the sun?
This guide explains who invested solar panels and how the interesting and surprising history of solar panels came about.
Who Invented Solar Panels? Solar Panel History
To those asking, who invented solar panels, while no individual can take credit for developing solar panels, an interest in solar panel technology began in the mid-19th century. 1
Solar panels, also known as photovoltaic panels or cells, have undergone gradual improvement over time by different scientists. 2
In 1839, for instance, a photovoltaic effect discovery by Alexandre Edmond Becquerel in which light would be converted into electricity marked the beginning of solar energy research and development.
A few years later, an American scientist, Charles Fritts, invented the first solar panel cell from selenium on a metal plate.
Scientists improved this concept while testing different elements to enhance energy proficiency. Thus, over decades, technological advances in solar energy have led to cheaper production techniques, new materials such as silicon, and proficient energy storage solar technology.
Solar panels offer the best alternative energy sources for domestic and industrial applications in ways that reduce over-dependence on oil, gas, and nuclear energy, making sustainable use of natural resources important.
importantly, when used in residential applications, they reduce drains on the energy grid, without causing damage to the ecosystem.
Since solar panels (on a farm) require huge swaths of land, which are covered by the panels, the eco-impact can be severe. However, when they are added to existing structures, this problem is nullified.
When Were Solar Panels Invented? (Who Invented Solar Panels?)
Solar panel history dates back to the 19th century. The photovoltaic effect discovery in 1939 by Charles Fritts, a graduate of Cornell University, led to the creation of the first solar panel cell, and was able to convert sunlight into electricity by 1883.
Although the selenium cell technology was groundbreaking, its effectiveness was in doubt. However, in 1954 three American scientists, Gerald Pearson, Daryl Chapin, and Calvin Fuller from Bell Labs developed modern solar panels from silicon.
The efficacy of these new panels to convert sunlight into electricity was remarkable, thus, ushering in a new era of solar panels and the push for renewable energy solutions. Unlike selenium-based solar cells by Charles Fritts, which had 1% efficiency, silicon-based solar cells attained an efficiency of 6%, a giant leap in terms of improvement. 3
At that point, Bell Labs sought to patent their invention, leading to the development of the solar industry today.
In 1956, Hoffman Electronics sold its first solar panel for use in space satellites.
Solar Panel Definition: What Does Solar Mean?
While solar is anything related to the sun, solar energy converts light to electricity.
Solar technologies such as photovoltaic and thermal collectors tap solar energy from the sun in photons.
So, what is the solar panel definition?
A solar panel is a gadget that converts sunlight into electrical energy. Usually, solar panels include a collection of photovoltaic cells created from silicon and other materials working together to absorb and convert light energy into electricity for domestic and industrial use.
Thus, whenever sunlight strikes the out surface of a solar panel, it activates an electron reaction generating environmentally friendly clean energy. However, it is pertinent to understand various terminologies for solar panel definition, as indicated below.
Wattage: This is the amount of power that a panel can generate. Since solar panels are produced in different sizes and output levels, one should understand their energy needs to select the right panel.
As a term, efficiency is the panel’s capacity to convert sunlight into electricity; panels with optimum efficiency generate more power with less space.
Net metering: Homeowners with solar energy systems get compensation for the additional power they add to the grid. This enables homeowners to save money and contribute to a cleaner environment.
What Are Photovoltaic Panels?
Popularly known as solar panels, photovoltaic panels are electrical devices that convert light into electrical energy.
They are created from silicon, a semiconductor material that absorbs photons from sunlight while releasing electrons that produces electricity.
Photovoltaic panels have become trendy because of their capacity to generate clean and renewable energy. A photovoltaic panel is made up of two sandwiched silicon wafers.
The upper layer is doped with boron, a low-concentration impurity that creates a positive charge carrier. On the hand, the lower layer is doped in high-concentrated phosphorous to create a negative charge carrier.
So, when light photons hit the panel’s outer surface, they create free charge carriers by displacing electrons. This is the first step for generating DC converted into AC for domestic and industrial use.
Photovoltaic cells generate clean energy free from greenhouse pollutants. This makes photovoltaic cells ecologically friendly.
Apart from easy installation, these panels are a better option because they do not require a large surface area to generate electricity like wind turbines. Despite the immense benefits of photovoltaic panels, they also have limitations.
Efficiency is one of the significant limitations of photovoltaic panels. The most effective photovoltaic cells can only convert about 20% of solar energy into electricity. 4,5
This also means about 80% of solar energy is lost as heat. Thus, generating adequate electricity from photovoltaic panels would take significant space and colossal investments.
Since photovoltaic cells require proper sunlight for optimum performance, they may not work perfectly in cloudy areas or regions with less exposure to sunlight. Though it is a renewable energy source, producing photovoltaic cells requires enormous energy and chemicals affecting the environment.
Solar Panel Technology
As a critical component of the renewable energy revolution, solar panel technology has become important lately as the world embraces cleaner, greener energy sources. With new developments emerging every day, solar panel technology is evolving each passing day.
However, silicon-based panels made from layers of silicon are popularly used. Not only are silicon-based solar panels cheaper to manufacture, but they have also been reliable over the years.
Thin-film solar cells made from photovoltaic material are equally gaining traction. 6 Unlike silicon-based panels, thin-film solar panels are flexible and widely used in different applications.
Concentrated Solar Power (CSP) is another solar panel technology making inroads. As opposed to other solar technologies that absorb light energy, CSP uses mirrors or lenses to concentrate light onto a surface to generate heat, which is then converted into electricity.
CSP may change solar energy generation moving forward because of its potential to create large amounts of energy in areas with high solar radiation. Despite solar panel technological advancement, the issue of efficiency remains the biggest challenge.
With 15-20% efficacy, further developments are required for the solar panels to generate enough energy. Nonetheless, researchers are working to enhance the efficacy of solar panels and develop zero-emission cars; green energy will soon replace non-renewable sources.
Solar Panel Production
Solar panel production aims for domestic and commercial applications.
Additionally, production begins with material selection.
Although silicon materials are used in producing solar panels, aluminum, plastic, and fiberglass panels are also used. 7 Silicon is often washed using hydrofluoric acid to eliminate dirt that may affect the efficacy of solar panels at the outset.
Then, an anti-reflective coating is used to enhance absorption. The second phase includes creating solar cells by making the p-n junction.
The p-n junction converts sunlight into electricity. This is followed by adding boron and phosphorus on any side of the silicon panel to create two semiconductors.
The n-type semiconductor exhibits an excess of electrons; however, the p-type semiconductor, which has a deficit of electrons, creates a potential difference leading to electric energy generation. Subsequently, various solar cells are connected in a series to form a module.
This is achieved by fastening wires to the terminals while placing a layer of EVA (ethylene-vinyl acetate) to protect cells. Ultimately, panels are framed with aluminum to protect cells from exterior damage.
The last phase of solar panel production is testing and quality control to determine their integrity. Before leaving the factory, solar panels are tested for efficiency and an output voltage that should fall within the rated power threshold.
Modules that fail to meet these requirements are either discarded or reconfigured.
What Is a Solar Panel Used For?
A solar panel converts sunlight into electricity to generate clean energy. Photovoltaic (PV) cells in a solar panel absorb sunlight as DC.
With the help of an inverter, DC is transformed into AC. The central purpose of a solar panel is to generate clean electrical energy with many applications.
Electricity from solar panels has various applications, including powering homes, businesses, vehicles, and communities. Also, using solar panels for power generation has many benefits.
Since solar energy is renewable, it is easy to replenish, making it sustainable and cheap in the long run. Again, solar energy is ecologically friendly and is the best option for conventional fossil fuels, including coal and oil, which are scarce resources.
over, solar panels generate clean energy devoid of greenhouse emissions and other pollutants. 8 Unlike conventional power generation, such as gas turbines and diesel generators, characterized by noise pollution, the silent nature of solar panels makes them environmentally friendly.
Solar panels are cheaper to install over the primary power grid in remote areas. The accelerated technological change has made solar panels effective and cheaper, making them the best alternative energy source for home and commercial applications.
Solar panels would shape these conversations following the contended climate change and ecological conservation debates.
When Were Solar Panels First Used?
The invention of solar panels marked the beginning of renewable energy use. These changes started in the nineteenth century when scholars sought ways to harness green energy to power homes, vehicles, and cities.
The first solar cell was used in the space industry in 1954 and ’58. 9 While using a small solar panel, the U.S. could launch Vanguard I then.
Essentially, solar panels are widely used in the space industry because they generate energy in remote areas.
Who Owns First Solar (First Solar Panels)?
The advents in solar panel technology led the world away from fossil fuels to embrace renewable energy sources.
However, Calvin Fuller, Daryl Chapin, and Gerald Pearson are among the owners of the first solar.
Fabricated in 1954, the original solar panel had an efficiency of 4%. This technological fete paved the way for a series of experiments culminating in the creation of modern panels.
Also, this set the accelerated pace and quest for renewable energy. While high costs and inefficiency characterized the initial stages of solar panels, mass production in the 1970s brought the costs down.
Again, the recent fabrication of solar panels has made it cheaper to install solar panels in homes, commercial spaces, and utility firms.
Which Country Invented Solar Panels?
Aside from wanting to know who invented solar panels, everyone wants to know the country that invented solar panels. What becomes apparent is that researchers and scientists of different nationalities working as a team birthed the solar panel technology.
Primarily, in 1839 Edmond Becquerel, a French physicist, discovered that certain materials could generate an electric charge when exposed to light. 10 These solar panels were inefficient in many ways.
However, Becquerel’s discovery was imitated in 1873 by Willoughby Smith, an English electrical engineer who found that selenium was a suitable semiconductor for the photovoltaic effect.
The breakthrough emerged in 1876 when Richard Day and William Grylls Adams in England discovered that selenium could produce electric current, particularly when exposed to light.
Five years later, an American inventor, Charles Fritts, designed the first commercial solar panel, though ineffective. Further improvements led to the creation of modern solar panels in 1939 by Russel Ohl, an American engineer. 11
Ohl’s technique was first used in 1954 in Bell Laboratories to make the first silicon solar cell. With an efficiency of 6%, Laboratories engineers became motivated by Ohl’s patent.
This breakthrough helped shape the production of modern solar panels, recognizing the U.S. as the country that invented solar panels.
How Much Power Does a Solar Panel Produce?
Solar panels are innovative in harvesting power from sunlight via the Photovoltaic effect. Nevertheless, the question of how much power does a solar panel produce depends on several factors, including;
- Size of solar panel: A large solar panel has a large surface capable of generating more energy than a small one. As a result, it is necessary to choose a suitable solar panel based on the application.
For example, using a large solar panel in areas that require a small panel would lead to inefficient use of solar energy resources, while using small panels in a large area would lead to under-utilization.
- Solar panel efficiency: It is crucial to note that positioning solar panels is vital. Specifically, a solar panel directly facing the sun will generate more energy compared to a panel partially under the shade.
- Solar panel location: The amount of sunlight varies based on region and season, which can affect the amount of energy. In cloudy or rain-prone regions, solar panels will generate less energy compared to sunny areas.
What Are the Different Types of Solar Panels?
The differences in solar panels revolve around carbon footprint. When buying a solar panel, it is only prudent to check out its carbon footprint. Common types of solar panels include;
Monocrystalline, polycrystalline, and thin film solar panels. Monocrystalline silicon panels: These panels effectively absorb and convert light into solar energy.
Since monocrystalline panels exhibit optimum proficiency, they are suitable for commercial and domestic applications.
Polycrystalline silicon panels: Unlike monocrystalline, polycrystalline panels are less efficient. However, they are cheap and suitable for commercial applications.
Thin-film panels: These panels are made from cadmium, amorphous silicon telluride. Since these panels are less effective, malleability makes them ideal for different applications.
Solar panels have a lifecycle of approximately 20-40 years, making them sustainable in the long term. Humans are keenly interested in knowing who invented solar panels, but they should worry more about reversing the carbon footprint.
How Long Do Solar Panels Last?
Solar energy is rapidly becoming popular due to its cost-effectiveness and environmental friendliness in generating electricity. But then, people are concerned about how long do solar panels last.
Solar panels can last up to 20 and 40 years. 2 Furthermore, their lifespan depends on the installation procedure.
Correct installation is necessary for the durability and performance of solar panels. Poorly installed solar panels are susceptible to damage, which shortens their lifecycle.
Professional experts should be consulted to install solar panels to guarantee a lengthy lifespan. Regular maintenance, especially repair, and cleaning can elongate the lifecycle of panels.
Regular cleaning helps remove dust, dirt, or pollen, which ensures they retain energy efficiency. over, routine inspection helps fix any damages affecting performance and lifespan.
Harsh climatic conditions also impact the lifecycle of solar panels. For example, hailstorms, extreme cold or heat, and strong wind can cause damage while reducing the panels’ lifespan.
The quality of the material used in the manufacture also affects the lifecycle of solar panels. Quality materials resist harsh climatic conditions and guarantee solar panels’ continuous power generation.
In contrast, low-quality materials can reduce the performance and efficiency of solar panels. 12
Do Solar Panels Work on Cloudy Days?
Solar panels are a sustainable energy source, but many people wonder, do solar panels work on cloudy days?
Nevertheless, cloudy days affect their efficiency because they decrease the amount of energy reaching the solar panels.
Clouds block sunlight making the panels generate less power. However, solar panels with solar photovoltaic cells do not require direct sunlight. 13 PV cells are more efficient in cool temperatures.
Although solar panels can generate electricity during cloudy days, they are often inefficient.
Thus, panels should adequately be installed with a MPPT charge controller to optimize efficiency on cloudy days and allow sunlight to diffuse.
What Is the Size of a Standard Solar Panel?
Having a rough idea of the size of standard solar panel remains paramount. In most cases, the size would enable one to gauge its performance.
Besides, the capacity of the solar panel to generate electricity is pegged on its size. Again, solar panel measurement is shaped by solar cells.
And this is a factor during construction. The solar panel size determines the amount of sunlight a panel can absorb.
The size of standard solar PV cells is 156 mm by 156mm.
What Are Carbon Footprint Solar Panels? Was This a Big Issue to the Person Who Invented Solar Panels?
While carbon footprint has attracted enormous attention now, it was a nonissue when solar panels were first invented. Nonetheless, carbon footprint solar panel can reduce the emission of greenhouse gases and carbon dioxide emitted into the atmosphere.
Unlike fossil fuels, solar panels generate electricity from the sun. Thus, solar panels considerably minimize carbon footprint because they depend on renewable energy without emitting toxic chemicals into the atmosphere. 14
However, the manufacturing and disposal of solar panels produce a carbon footprint that is pretty high. This amount is offset slightly if the form of energy replaced was generated by fossil fuels (like coal and gas), but less so when replacing hydro electric or nuclear sources.
As technology advances, the energy required to produce solar panels gradually decreases, making them more viable and sustainable. Solar panels generate clean electricity, but the location matters to the planet as well.
When asking who invented solar panels, know that it took many centuries to get to where we are today.
Carbon Footprint: Solar Panel Manufacturing In 1 Simple Explanation
Do Solar Panels Work on Cloudy Days, at Night, in Rain? Yes No (Here’s How)
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