Solar Panels: price, specs, what to know about solar energy
As the world strives to reduce its dependence on fossil fuels and move toward more sustainable forms of energy, solar energy is something everybody wants to tap into. A perennial energy source, sunlight is available in most parts of the world for significant periods of time in the day.
To harvest this energy, though, one needs specialized equipment, and solar panels are the most commonly used method. If you do not know how they work, what they are made from, or how much energy they can generate, here’s a basic guide to getting you started.
What are solar panels?
Solar panels are devices that convert light into electricity. They are called solar panels because, on most occasions, the light from the Sun, or Sol as astronomers like to call it, is the most abundant form of light and easily accessible, too.
A solar panel consists of a particular layer of silicon cells, a metal frame in a glass casing that has a special film around it, and connections that link the components to each other, making an array. Smaller units inside a panel are called solar or photovoltaic cells, each capable of converting light into electricity.
When arranged on a panel, solar cells can harvest more light being incident in the area and convert it into electricity. This is why one often sees spacecraft equipped with large solar panels designed to cater to the electrical power needs of the space vehicle.
History of solar panels
Solar panels might be common today, but their history can be traced back more than 100 years. Before this, energy from the Sun was being accessed to heat water and turn it into steam to drive machinery.
However, French scientist Edmund Becquerel observed the photovoltaic effect (the generation of voltage and electric current in a material exposed to light). Through experiments with electrolytic cells, he established that the electricity flowing between two platinum electrodes coated in silver chloride or silver bromide is slightly stronger in daylight than in the dark. At the young age of 19 created the first photovoltaic cell that could convert light into electricity.
In 1883, Charles Fritts created the first solar cell using the semiconductor selenium, coating it with an extremely thin layer of gold. Fritts‘ panel was also installed on a rooftop in New York, but its high cost and one percent energy conversion efficiency made it unviable in the long run.
Russell Ohl first patented solar cells made with silicon, and the first solar panel using silicon cells was created in 1954. These panels were primarily meant to produce power for spacecraft but also found their application in calculators by the 1970s.
How do solar panels convert light into electricity?
A solar panel consists of a large array of solar cells connected. Solar cells are usually made from silicon, the second most abundant material on the planet after oxygen. Since silicon is a semiconductor, it can act as an insulator and a conductor.
Inside a solar cell, silicon is arranged into two different layers: the P-type, which can receive electrons, and the N-type, which can give electrons away. The p-type silicon is produced by adding atoms—such as boron or gallium—that have one less electron in their outer energy level than the silicon, creating a vacancy. The n-type silicon is made by including atoms, such as phosphorus, that have one more electron in their outer level than silicon.
The N-type layer is placed to face the sunlight, while the P-type is placed underneath the N-type layer.
The light from the Sun comes in small packets of energy called photons that can cause the N-type layer to lose electrons. These are collected on an aluminum layer underneath, also known as the back sheet. Theoducinghe electrons flow back and forth, this produces an electric current, which can flow down wires and out of the solar cell to a storage device.
What is the efficiency of a solar panel?
The efficiency of a solar panel is the amount of electricity it can produce from the light incident on its surface. Solar panel efficiency is determined under Standard Test Conditions (STC) where the temperature is 25 degrees Celsius and irradiance is 1000 W/ square meter. This is the equivalent of sunlight received on a bright sunny day by a tilted solar panel. An efficiency of 20 percent would mean that a one-square-meter solar panel will produce 200 Watts of electricity.
In the real world, the conditions are impacted by a host of factors such as wind, humidity, UV radiation, chemical exposure, etc., and the actual efficiency of the panel is lower than that obtained during the STC. The material used to make the solar cell can also increase energy conversion efficiency, with monocrystalline solar panels delivering the highest efficiency among commercially available panels.
Behind the business scenes, scientists have been looking to increase the efficiency of solar panels and, in recent times, have managed to crack the 30 percent barrier of solar efficiency. This has been made possible with the use of perovskites, calcium titanate crystals, or materials with similar structural arrangements and properties that can be used to enhance the efficiency of solar cells.
Advantages of solar panels
The most significant advantage of using solar panels is the ability to tap into an unlimited, non-polluting, renewable energy source. As we improve our methods to harvest the energy that is incident on our planet every single day, we will be able to transition to a clean energy source for all our future needs.
Unlike conventional source of power that requires one to be connected to the grid to receive an uninterrupted supply, by using batteries, solar panels can give us the freedom to stay in far-off places and still have easy access to energy. It is hardly a surprise that scientists turned to solar energy to power spacecraft that have traveled to Mars and even beyond instead of relying on nuclear energy.
Once installed, solar panels have long lifetimes with very little maintenance needed. Solar panels need to be kept clean for the highest energy conversion efficiency, but other than that require no maintenance since there are no moving parts in the energy generation process. The energy storage end requires maintenance, but the system usually does more than pay for itself in the years of service.
Users in many places can also sell excess energy generated by the panels to utility companies and earn money for doing virtually nothing once the installation is completed.
Disadvantages of solar panels
Harvesting solar energy is not straightforward, though. While the cost of generating solar power has reduced considerably over the past few years, the upfront cost of installing a solar panel, especially on a small scale, is still reasonably high. Apart from buying the panels, one also needs to purchase the inverter and energy storage solution, which can be pretty expensive.
Harvesting solar energy is also heavily dependent on weather conditions. Even though the panels work under cloudy conditions, a few days of rainy or snowy weather can impact your energy reserves. For those who need to heat water during the night in the winter, a solar panel might not meet the need.
Conventionally, solar panels occupy a lot of space and depending on the size of your house and energy needs, you might need to figure out some extra real estate where they can be installed. The efficiency of home solar panels also depends on the type of roof and the direction it faces. With advances in technology, it may be possible to buy transparent solar Windows. But if you want to buy something now, these might not deliver the energy conversion efficiencies you would expect from them.
Installation of solar panels in large numbers to make solar farms has been associated with soil compaction and increased erosion. Post their lifetime, solar panels have become a concern since they are yet to find their way into the recycling economy, and dumping them in landfills can leach heavy metals such as lead and cadmium into the soil.
Innovation in the solar energy sector is taking a new turn, with newer materials being used to make solar panels better and cheaper. Solar panels are set to make a significant impact on how we access energy in the future.
Charles fritts solar cell
While solar panels today provide many benefits, they are barely more than 20 percent efficient. New materials and even artificial intelligence may soon increase output tremendously.
Solar Panel Background
The process for converting sunlight into electrical current was discovered way back in 1839 by French physicist Edmond Becquerel. In 1883, New York inventor Charles Fritts created the first solar cell by coating selenium with a thin layer of gold, though it wasn’t until the 1950s that Bell Labs demonstrated the first modern silicon-based solar cells. (A Brief History of Solar Panels in Smithsonian Magazine)
Ever since that demonstration, progress to increase solar panel efficiency has been slow.
Solar Panel Efficiency
Most solar panels are between 15 percent and 20 percent efficient, according to Solar Labs, though a few high-efficiency solar panels can exceed 22 percent. That efficiency number is a measurement of the panel’s capacity to convert sunlight into power. A solar panel with a 20 percent rating, for instance, converts 20 percent of the sun’s energy into solar power.
|Photo courtesy of Fire Mountain Solar
Solar panel efficiency is primarily determined by two main factors, the photovoltaic cell efficiency based on the cell design and silicon type, and the total panel efficiency based on the cell layout, configuration and panel size. Cell efficiency is calculated by the fill factor, CER explained, which is the maximum conversion efficiency of a photovoltaic cell at the optimum operating voltage and current. Cell efficiency is affected by the cell structure and type of substrate used, which is generally either P-type or N-type silicon. The type of material, such as monocrystalline silicon or cadmium telluride, has an influence on how light is converted to electricity, Solar Labs explained. The arrangement of wires and busbars that capture and transport power on a solar panel affects efficiency too. Solar panels cannot absorb energy from the entire solar spectrum, so some wavelengths of light that solar panels cannot process bounce back off the panels. A solar panel’s efficiency may also be reduced if light is reflected away, which can be affected by the glass layer on top of a solar cell.
The Materials to Produce Solar Panels will Change
After incremental progress for so long, the pace of change has increased rapidly over the past decade and innovations are underway that can make solar panels far more powerful.
One of the most promising innovations is the use of perovskites. Researchers from the University of Washington, University of Toledo, University of Toronto, Northwestern University and Swiss Federal Laboratories for Materials Science and Technology collaborated on improving the durability of perovskite solar cells, according to Science Daily. Perovskite solar cells offer a route to lowering the cost of solar electricity given their high-power conversion efficiencies and low manufacturing cost, said University of Toledo professor Yanfa Yan. The team discovered the ingredient that enhances adhesion and mechanical toughness.
Researchers at Purdue University who are also working with perovskite have created multifunctional ligands that improve the charge transfer, power conversion capability and long-term stability of perovskite solar cells. “Our conjugated ligands have a perfect fit into the perovskite crystal lattice and can help build a 2D-on-3D perovskite heterostructure, which further enhances the solar panel’s stability,” researcher Letian Dou said.
Another innovation combines perovskite semiconductors and quantum dot solar cells to make perovskite quantum dot solar cells. Perovskites are salts that form into a novel class of hybrid semiconductors, while quantum dots are nanoscale semiconductors. Whereas commercial solar panels today generate heat at the cost of energy efficiency, perovskite semiconductors and quantum dot solar cells have unique properties that are able to retain more energy as electricity rather than heat. National Renewable Energy Laboratory scientist Joey Luther has found that perovskite/silicon tandem solar cells have up to 32 percent efficiency.
Researchers at Martin Luther University Halle-Wittenberg recently said they discovered a new method to increase the efficiency of solar cells by an incredible factor of 1,000, by creating crystalline layers of barium titanate, strontium titanate, and calcium titanate. While it is still early days and much more information is needed, the announcement shows that researchers are continuing to look for even better solar panels. If the innovations such as this one are possible, they could upend current methods.
Form Factors and Processes will Evolve
Emerging technologies could turn Windows into transparent solar cells that generate electricity, CNET reported. A solar window with a transparent coating or material gathers energy from the light passing through the window and stores it as electricity. While transparent solar technology is less efficient than the photovoltaic panels on rooftops, they could power devices adjacent to the window such as electric blinds. Ubiquitous Energy, which is developing solar Windows, uses a special glass coating applied during the normal manufacturing process of Windows to capture ultraviolet and infrared light energy.
In Italy, the 3SUN Gigafactory is developing bifacial panels which could use both direct sunlight and sunlight reflected from the ground onto the back of the panel. Research is currently focused on tandem cells, which consist of two overlapping cells, one “traditional,” and the other made of perovskite. The panels have an efficiency level of up to 24 percent and a lifespan of up to 35 years.
The World Economic Forum (WEF) reported that researchers from UNSW Sydney and Exciton Science made a breakthrough in infrared technology that could lead to solar panels that work at night. The researchers successfully tested a thermo-radiative diode that converts infrared heat into electricity, using technology similar to that used for night-vision goggles. While the amount of energy produced is currently small compared to solar panels, about 0.001 percent, it shows the possibility of developing solar panels producing energy even at night.
In the UK, a start-up founded by researchers at the University of Exeter is working on converting solar energy to electricity via an innovative solar glass brick which can be incorporated into the fabric of a building. The bricks fit into either new buildings or as part of renovations in existing properties. Intelligent optics can FOCUS incoming solar radiation onto small solar cells, enhancing the energy generated by each solar cell.
Researchers at Stanford University are working on concentrating the amount of light that hits a solar cell and getting the same amount of light to hit an area a third of the size, which could make solar panels more efficient in indirect light conditions.
AI can Improve Efficiency
Along with using new materials and practices, work is underway to use artificial intelligence (AI) to increase efficiency and reduce costs. Key areas include using AI algorithms to optimize the positioning of solar panels and reduce shading, which improves solar energy production, and using AI-based predictive analytics to identify potential issues with solar panels or inverters before they become major problems, which reduces maintenance costs and downtime. AI is also beginning to be used to analyze weather patterns and solar radiation levels to predict future solar energy production, improve energy planning and grid management. AI could then optimize the performance of energy storage systems and manage the performance of solar panels, inverters, and other components of solar power systems.
While the timing for full deployment of these innovations and their actual impact or timeline are uncertain, it’s clear that major changes are underway in solar technology. Some observers have even said the pace of innovation might be too fast, as solar cells produced today may be obsolete tomorrow. While companies and consumers planning to install solar panels have long had to consider whether to install today or wait, the considerations in making a decision are becoming even more complex given the scale of innovation underway.
Looking Back at the History of Solar Energy
Solar energy is not a new technology. Humans and the sun share a long history that spans many centuries. Thousands of years ago, we used magnifying lenses to ignite the kindling that warmed our caves. Today, we use solar energy to power our homes, our businesses and our streetlights. Heck, we even strapped solar panels onto the rovers that traverse the Martian landscape.
In this article, we break down this vast history of solar power into 12 significant milestones. We discuss the most important scientific breakthroughs in solar technology, but we also leave a little room to share a few light-hearted mile markers, including the fabled solar-powered “death ray.”
Solar power truly is the stuff of legends.
Milestones in the Development of Modern Solar Technology
7th Century B.C.E.: Humans Used Magnifying Glass to Light Fires
When you think of “B.C.E.,” The Flintstones, cave drawings and primitive living arrangements come to mind. But quite the contrary, my friend. In the 7th century B.C.E., humans discovered that, by concentrating the sun’s rays onto a small area using a convex lens (thicker in the center and thinner at the edges), they could FOCUS enough heat to create fire.
Also known as burning glass or fire lenses, this technology is as simple as solar energy gets. It’s the first significant form of solar technology other than drying fruits and meats under the sun.
212 B.C.E.: Archimedes and the Legendary Solar Death Ray
The next significant milestone was the invention of burning mirrors. Similar to burning glass, this form of technology involves reflecting the sun off of mirrors rather than concentrating it.
This can be best illustrated through the lens of none other than Greek mathematician Archimedes and his fabled “death ray.” Consisting of giant mirrors that concentrated the sun’s rays onto enemy ships, this tool was so powerful that Archimedes allegedly decimated an entire Roman fleet! 2
Many wonder whether this historical account was just a tall tale. The Massachusetts Institute of Technology conducted a successful experiment in 2005. 3 However, the death ray was tested on Mythbusters in 2006, but it was declared “Busted” after having failed twice. 2
Fun fact: This is still how the Olympic flame is lit: Through concentrated solar rays via a parabolic mirror. 4
Whether it was truth or trick, it’s not ours to say. Our point is that this technology, which was indeed not a myth, serves as the direct precursor to concentrating solar power (CSP) plants. They use highly reflective mirrors to concentrate sunlight on a single point then heat water to drive steam turbines and produce electricity.
1839: Edmond Becquerel Discovered the Photovoltaic Effect
While solar power was a recognized thermal energy source for centuries, the building blocks for modern photovoltaic (PV) solar panels didn’t arise until the early 19th century with Alexandre-Edmond Becquerel, a French physicist.
While many have debated who should receive credit for solar cell technology, nearly everyone acknowledges that Edmond Becquerel discovered the photovoltaic effect. This process generates an electric current when a material is exposed to sunlight. Becquerel’s experiment involved two metals, either gold or platinum, being placed in an electricity-conducting solution and exposed to sunlight. 5
In essence, this is how modern PV cells within solar panels work, and it would later be the basis of Einstein’s photoelectric effect (check it out below).
1876: William Grylls Adams Discovered Certain Metals Produce Electricity When Exposed to Light
A few years earlier in 1873, English electrical engineer Willoughby Smith discovered that the element selenium has photoconductive properties. This meant it had increased electrical conductivity caused by the presence of light. This finding led to William Grylls Adams and his student, Richard Evans Day, to discover that selenium could produce electricity. 6
Although they didn’t generate enough electricity to power anything, it did prove that materials didn’t need to be dunked in any solution or heated. Instead, they could produce electricity with only sunlight. 7
1883: Charles Fritts Created the First Solar Cell with 1% Efficiency
The very first solar cell was created by Charles Fritts. The American inventor took selenium wafers, similar to the silicon wafers used in today’s solar panels, and wrapped them in thin gold foil. This setup was sufficient enough to generate an electric current with a little less than 1% efficiency! 8
Today’s silicon solar cells operate at around 15 to 18% efficiency, so Fritts hadn’t solved everything. 9 Still, his discovery would have many applications — even today. The element is still used to test light exposure for photography, so, next time you snap a pic, remember Charles Fritts!
1921: Albert Einstein Won the Nobel Prize for His Discovery of the Photoelectric Effect
You might know Albert Einstein for his theory of relativity and famous equation, E=mc 2. However, his Nobel Prize was for neither of those — it was actually for discovering the photoelectric effect in 1905. This principle states that, when sunlight shines on a metal, it emits electrons from the surface of the material. The energy from sunlight (photons) then transfers to the atoms’ electrons and knocks them loose.
This discovery was so significant that it has influenced the development of many types of technology, from electron microscopes to modern solar cells as we know them today. 10
1941: Russell Ohl Patented the First Silicon Photovoltaic Cell
However, that’s not exactly what Einstein intended to do with his discovery. Thus, in 1927, American engineer Russell Ohl went to work at Bell Labs to improve radio broadcasting capabilities. Most of Ohl’s research involved purifying silicon crystals so radio tuners could handle higher frequencies. 11
Little did he know that he would accidentally discover the p-n junction, the building block for how solar panels work to this day! 12 Here’s what happens:
- The “p” side of the metal is positively charged silicon.
- The “n” side is negatively charged.
- When the negative silicon is exposed to light, it knocks loose the negative electrons, which are attracted to the positive side.
- This creates an electric current between the two panels.
This discovery is why many modern solar panels, including the ones we operate at Chariot, are made from ultra-pure polysilicon.
1954: Bell Labs Unveiled the First Practical Solar Cell
Next, it’s time to introduce the first silicon solar cell that could provide significant amounts of electricity. On April 25, 1954, Daryl Chapin, Calvin Fuller and Gerald Pearson demonstrated a solar cell that was 4% efficient. efficient than any other solar-powered device of that era, it produced several hours’ worth of photovoltaic (PV) power. 8
From this point on, solar would grow exponentially, and PV cells would only get more efficient. This was a major breakthrough in the history of solar power.
1958: The First Solar-Powered Satellite Successfully Launched into Space
We mentioned the Mars Rover above, but many other events had to happen before that was possible. The first and most significant of these was the launch of space satellite Vanguard 1. It was the first successful satellite to use solar power, and it’s actually the oldest satellite still orbiting Earth. Although the satellite used a small solar array, the cells produced around 1 Watt with 10% efficiency. This is why solar energy remains a main source of power for space applications. 13
1973: The University of Delaware Built the World’s First Solar Photovoltaic Powered Home
The Institute of Energy Conversion at the University of Delaware created one of the world’s first homes that converted solar energy into heat and electricity for domestic use. The house utilized rooftop PV systems as well as solar thermal energy (i.e. solar heating and cooling) during the day. At night, the house used power from the grid since solar electricity generation doesn’t work at night. 14
This setup would eventually morph into the concept known as net metering. This is where a homeowner’s solar panel provides electricity during the day — and often sells back excess generated electricity to the grid — and the electric company provides power at night.
2013: President Obama Installed Solar Panels on the White House
Technically, the 43rd president was the third one to do so, as solar panels were installed two other times before Obama’s time in office. In 1979, Jimmy Carter was the first president to install solar panels on the White House — 32 of them! 15 However, the Reagan administration dismantled them due to a roof leak and chose not to reinstall them, with his chief of staff calling them “a joke.”
In 2003, President George W. Bush brought solar power back to the White House by installing a photovoltaic system, as well as two solar thermal systems that heat water. 15 Obama bolstered that setup with even more solar panels in 2013. 16
Here’s why we included this: These acts were largely political. According to the Department of Energy, Obama wanted to show that solar technologies were available, reliable and ready to install in homes across the country. 17 In 2016, Obama furthered his commitment to clean energy by announcing the Clean Energy for All Americans Initiative. Through this initiative, the administration announced a goal to bring 1 gigawatt (GW) of solar electricity to low- and moderate-income families by 2020. 18
For reference, 1 gigawatt of electricity is equal to 3.125 million PV panels. 19 Wow!
Present Day: Solar Energy Powers Millions of Homes Around the World
So, this brings us to the present. You must be wondering, “What is the state of solar energy today? importantly, where is the industry expected to be five years from now? 10? 20?”
According to the Solar Energy Industries Association, the U.S. has 69.1 GW of total installed solar PV capacity as of September 2019. This is enough energy to power more than 13 million homes! By 2024, more than 15 GW of PV capacity will be installed annually. 20
Keep in mind this is just the U.S. PV capacity, which doesn’t include Concentrated Solar Power plants and passive solar. Plus, this is with panels that operate at an average of 15 to 18 percent efficiency.
Clearly, solar still has a ways to go — but we’re so excited about what the future entails! Average solar panels by 2040 may be operating at 30 or 40 percent efficiency. Solar panels might also become the most affordable energy resource out there. The sun is the limit when it comes to innovation in solar tech.
Project Brain Light
Using Sunlight as Renewable Energy
What is a Solar Panel?
Sunlight is made up of energy particles called photons. Solar panels convert these photons into electricity that we can use to power our homes and electrical devices. Before solar panels were invented, solar energy was first used to create steam to drive machinery in factories. After the discovery of the photovoltaic effect in 1839, the first solar cell was created by Charles Fritts. Solar cells are used to create solar panels as we know them today. The first main application of solar panels was for use in space satellites. Solar panels also made their appearance in calculators in the 1970s. These first generation solar panels were made from wafers of polycrystalline silicon.
Newer, second generation solar panels are made up of several solar cells that are composed of amorphous silicon, cadmium telluride, gallium selenide, or gallium arsenide thin film layers. Solar panels are used to create clean energy from the sun. Sunlight photons are absorbed by the solar cell, which results in electrons becoming excited (creating negative charges) in the system. These electrons hit the surface of the solar panel and are knocked free to travel along the electric field in the direction of the current. The electrons can be converted into energy – which can be used to power things like light bulbs and more – before it returns to the solar cell.
What are Dye-Sensitized Solar Cells?
Third generation solar cells are among the newest emerging technologies including Dye-Sensitized Solar Cells (DSSCs). There are several advantages of DSSCs over traditional silicon solar cells, even though they have a lower energy conversion efficiency. DSSCs can operate under low light, can perform under higher temperatures, require less manufacturing energy, are easy to adjust its properties using eco-friendly materials, and can use a variety of substrates.
How did DSSCs come to be invented?
Well, the first report of the dye sensitized photovoltaic effect (generating an electric current from sunlight) was in 1877 by J. Moser. In 1960, the first wide Band gap semiconductor (zinc oxide) with different dyes was discovered. A wide Band semiconductor has 2. 4 eV energy gap between the electron filled state (called the valence Band) and the unoccupied Band (called the conduction Band). The wide Band gap means that it needs a lot more energy to excite electrons than silicon does, which has a Band gap of 1.1 eV. By changing the semiconductor, one can adjust the properties of the solar panel.
Titanium dioxide is a common wide Band semiconductor used in DSSCs. The electrodes are made of a conducting glass to allow for electron flow. The working electrode (where the electrons get excited) is coated with titanium dioxide nanoparticles. The dye of choice is attached to the titania surface. The combination of the absorbed dye and titanium dioxide absorb photons from the sun to create excited electrons. The electrons travel along the circuit to the counter electrode. The electrolyte solution in between the electrodes balances the electrons on each side. DSSCs are a heavily-researched field, with the goal of increasing the solar energy conversion efficiency of DSSCs to become a more practical rival to the traditional silicon solar panels, which currently have a higher efficiency.
Solar panels are a booming renewable energy source that has been researched and modified since the 1800s. The solar panels you see on solar farms or on top of houses are second generation silicon solar panels, which currently have the highest energy efficiency. Current research on third generation solar cells like DSSCs and perovskites is being conducted in order to find alternative materials to build the solar panels and increase their efficiency.
- Advantages of DSSC: GCell. G24. (2014, July 17). Retrieved May 8, 2022, from https://gcell.com/dye-sensitized-solar-cells/advantages-of-dscc?msclkid=79786ecdcef911ecb372a81b680ecf51
- Mbonyiryivuze, A Zongo, S Diallo, A Bertrand, S Minani, E Yadav, L. L Mwakikunga, B Dhlamini, S. M Maaza, M. (2015). Titanium Dioxide Nanoparticles Biosynthesis for Dye Sensitized Solar Cells application: Review. Physics and Materials Chemistry, 3(1), 12-17.
- Mr. Solar. (2022). How does a solar panel work? Retrieved May 8, 2022, from https://www.mrsolar.com/what-is-a-solar-panel/