First Solar plans a 3.3 GW Indian module fab
The U.S.-based manufacturer is planning a vertically integrated thin-film solar module manufacturing facility in India. The factory will likely be built in Tamil Nadu and become operational in the second half of 2023.
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First Solar said it plans to invest 684 million in a new, fully vertically integrated photovoltaic thin film solar module manufacturing facility in India. Contingent upon permitting, and pending approval of Indian government incentives that are satisfactory to the Arizona-based First Solar, the facility is expected to be built in the state of Tamil Nadu and commence operations in the second half of 2023.
The planned facility is projected to have a nameplate capacity of 3.3 GWdc.
First Solar produces its thin film PV modules using a fully integrated, continuous process under one roof and uses a Cadmium Telluride (CdTe) semiconductor.
In early June, First Solar said it would invest 680 million to expand its domestic U.S. photovoltaic solar manufacturing capacity by 3.3 GW annually, representing an implied capital expenditure of around 0.20 per watt. The company said it intended to fund construction of its third U.S. manufacturing facility in Ohio with existing cash resources.
All totaled, the company said that its nameplate manufacturing capacity will double to 16 GWdc in 2024.
Well-defined goal
In a statement, Mark Widmar, CEO, said that India offers an attractive market for First Solar in part because the company’s module technology is advantaged in a hot, humid climate. He said the country has “a well-defined goal that will need over 25 GW of solar to be deployed every year for the next nine years.”
The International Energy Agency (IEA) has projected that India will overtake the European Union (EU) to become the world’s third-largest consumer of electricity by 2030, as the country’s population and Gross Domestic Product (GDP) continue to grow. As part of its climate targets, India has committed to ensuring that renewables will make up 40% of its energy portfolio by 2030. The country is forecast to account for almost 20% of the world’s installed solar capacity by 2040.
The facility will be designed using the manufacturing template established for First Solar’s recently-announced factory in Ohio. Combining highly skilled workers with Industry 4.0 architecture, machine-to-machine communication, artificial intelligence, and Internet of Things connectivity, it will feature high degrees of automation, precision, and continuous improvement.
The company said it continues to optimize the amount of semiconductor material used by enhancing its vapor deposition process. First Solar also operates a recycling program that recovers more than 90% of CdTe for use in new modules.
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David Wagman
David Wagman was a senior editor at pv magazine USA. David is a seasoned energy journalist and editor.
First Solar plans factory expansion in Ohio, hands Biden administration a US manufacturing win
First Solar, a solar manufacturer headquartered in Arizona, said this week it would spend nearly 700 million to expand its solar manufacturing footprint in Ohio, giving the Biden administration a concrete win in its bid to have more clean energy equipment produced in the U.S.
The investment will add more than 3 gigawatts of capacity to First Solar’s existing plants in the state. The company last announced an expansion of its U.S. operations in 2018. shortly after the Trump administration imposed tariffs on imported solar cells and modules. First Solar is the largest solar manufacturer in the United States, which has seen a proliferation of new and expanded solar factories in recent years as companies sought to evade tariffs.
First Solar’s thin-film cadmium-telluride solar modules were never subject to those tariffs, however. While its peers have paid millions of dollars in tariffs to deliver products to the U.S. market, First Solar has continued to import panels made abroad without paying Section 201 duties, offering the company a distinct market advantage.
Now that President Biden has picked up the Trump administration’s impetus to encourage U.S. manufacturing, First Solar is positioned to continue to benefit. The tariffs don’t step down until early 2022. and the administration has not indicated whether it plans to seek an extension of them.
“ We brand ourselves as America’s solar company,” CEO Mark Widmar said. “ We hope this [factory] demonstrates First Solar’s commitment to the Biden administration’s goals.”
Though Widmar said First Solar believes in “ the intent and the spirit” of the Section 201 tariffs to create a “ level playing field” for domestic industry, the company is currently advocating for industrial policy that offers incentives for both domestic supply and demand. Widmar pointed to examples such as a solar investment tax credit with a longer timeline and a tax credit for new manufacturing.
The new Ohio plant will bring the U.S. share of First Solar’s global manufacturing to just under 50 percent. Once the plant is operational, First Solar could supply about 60 percent of its U.S. demand with American-made modules, according to Widmar. The company is completely sold out of modules through the rest of 2021. with 60 to 70 percent of its 2022 product already sold as well.
Get Caught Up
Can the US manufacture enough solar panels to meet its surging demand?
The factory expansion will also allow the company to singlehandedly supply nearly half of the U.S.’ total demand for large-scale solar equipment, “ further reducing the country’s dependence on foreign suppliers,” said Kelsey Goss, a solar analyst at Wood Mackenzie, in an email.
U.S. utility-scale solar is First Solar’s largest market. On the company’s most recent earnings call, held in late April, Widmar said the company is “ uniquely positioned to support domestic energy independence in the United States and play a leading role in [Biden’s infrastructure] plan” because of its distinctive technology.
U.S. Energy Secretary Jennifer Granholm called the factory announcement “ the perfect embodiment of President Biden’s strategy to build out domestic manufacturing and supply chains for critical industries,” in a statement on the news.
The White House’s infrastructure package, unveiled in March, includes many provisions to boost clean energy. In addition to supporting incentives that would increase renewables and electrify industry, President Biden has emphasized a goal to have much of that equipment manufactured in the U.S. Currently, the majority of the solar supply chain is located in Asia.
President Trump was an opponent of renewables but a supporter of boosting U.S. manufacturing. His administration established Section 201 tariffs with that latter goal in mind. Biden has continued to support some Trump-era solar trade policies. It’s unclear whether supporters of the tariffs will advocate for their extension.
First Solar, which has publicly supported the tariffs, said it now prefers a less volatile policy with better “ industry alignment.” The Section 201 tariffs splintered the solar industry, dividing domestic manufacturers and developers. A tariff extension is not the company’s “ preferred path,” said Widmar.
“ Our advocacy is going to be about industrial policy. However, if for whatever reason we’re unsuccessful accomplishing a more constructive industrial policy, then we may have a voice as it relates to 201 ,” he said.
Emma Foehringer Merchant is a former staff writer for Canary Media. She has covered clean energy and climate change at publications including Greentech Media, Grist and The New Republic.
Made-in-Ohio solar panels benefit from federal incentives, supply chain politics
About two decades after cadmium telluride solar panels were commercialized in Ohio, the maturing technology is finding momentum thanks in part to its domestic manufacturing and supply chain.
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A once-novel solar power technology with Ohio roots is having a moment in the sun, along with two Toledo-area manufacturers.
Scientists had experimented with cadmium telluride solar panels in the lab since the 1950s, but the technology was commercialized just two decades ago after important groundwork by a pair of Ohio entrepreneurs who founded what would eventually become First Solar.
After years of fighting for a niche next to cheaper and more efficient crystalline silicon solar cells, cadmium telluride has recently closed the gap on cost and energy output. Cadmium telluride panels hold the largest worldwide market share among thin-film solar technologies, which use very thin layers of semiconductor material, versus thicker rigid crystalline silicon.
On top of technological advances, the sector is poised to benefit from ongoing supply chain politics and new federal climate change legislation that incentivizes domestic manufacturing.
Those trends are fueling a solar manufacturing boom in Ohio, where despite hostile state and local policies against solar farms, two cadmium telluride manufacturers have announced major expansions that promise to add hundreds of jobs in the coming years.
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First Solar plans to open its third Ohio factory later this year in Lake Township. That 3.3-gigawatt plant will be followed by a 1.3-million-square-foot research and development facility in Perrysburg, slated to open next year. Plans call for a fourth U.S. factory to open in Alabama in 2025, bringing the company’s total U.S. production capacity to roughly 10 GW.
Meanwhile, Toledo Solar, whose panels go mainly to commercial and residential users, is tripling its production capacity from 100 to 300 megawatts this year. Although the company is much smaller than First Solar, which targets the utility-scale market, “that’s a big deal for us,” said CEO Aaron Bates.
“The Toledo area, with its deep ties to the glass industry, was a natural incubator in the early years of our business,” said Kuntal Kumar Verma, chief manufacturing officer for First Solar. than 20 years later, northwestern Ohio “is home to a pool of thin-film solar manufacturing knowledge that is perhaps unparalleled anywhere in the world.”
Why Ohio?
The cadmium telluride solar sector’s origin story in Ohio starts with two superheroes of the glass industry.
Harold McMaster grew up as a farm boy in northwestern Ohio, and Norman Nitschke spent his boyhood in East Toledo. The two pioneered the manufacture and use of tempered glass — the stuff used for car windshields so it won’t break into jagged shards. They became co-founders of several companies, including Glasstech.
McMaster and Nitschke then began working on solar energy through Glasstech Solar. That work led to Solar Cells, Inc. Under McMaster’s leadership, the company developed the basic vapor deposition process for its cadmium telluride solar cells in 1997.
The process uses hot gas to crystalize a layer of cadmium telluride whose thickness measures roughly 3% of a human hair. That layer, glass and other materials make up the solar panel’s “sandwich.” Production takes less time than that for crystalline silicon panels, which represent the majority of solar panels used worldwide.
After the sale of a controlling interest in the company to an Arizona-based investment firm, Solar Cells, Inc. became First Solar in 1999 and opened its first manufacturing plant in Perrysburg.
Yet it took years before the cells’ efficiency improved enough to become competitive. In 2016, First Solar achieved an energy conversion efficiency of 22% in the lab. A 2019 study by company scientists and research at the National Renewable Energy Laboratory refined on that work, reducing the risk of instabilities that could lessen efficiency.
Toledo Solar chose the Toledo area when it started up in 2019, so it could capitalize on the knowledge base built up by First Solar and nearby universities. Starting elsewhere would have been “such a lift, and it would be so expensive,” Bates said.
Now cadmium telluride solar is a proven technology, and it’s competitive with crystalline silicon, said scientist Lorelle Mansfield at the National Renewable Energy Laboratory. “It’s in the field. It’s utility-scale. It’s out there, and it’s working well,” she said.
The cadmium telluride sector currently supplies roughly 40% of the U.S. utility-scale market and about 5% of the worldwide market, according to the U.S. Manufacturing of Advanced Cadmium Telluride Photovoltaics Consortium, or US-MAC. Members include various companies, universities and the National Renewable Energy Laboratory.
A Global Market Estimates report released in January projected that the global cadmium telluride market would grow at a compound annual rate of 12.5% from 2023 to 2028 as the energy transition continues.
Head-to-head
Although First Solar and Toledo Solar don’t compete with each other, they and other cadmium telluride companies in the global market do compete with crystalline silicon.
By late 2020, First Solar reported an average efficiency rate of 18% for its commercial modules. That’s at the low end of the 18% to 22% range the Department of Energy has reported for crystalline solar panels.
However, cadmium telluride can “deliver up to 4% more energy in hot climates and up to an additional 4% more energy in high humidity,” Verma noted. The theoretical efficiency of cadmium telluride panels is also higher — more than 30%. That’s because the semiconductor layer can respond to a wider range of light energy, Bates said.
Cadmium telluride panels also offer cost savings in production because they require less materials, less energy and less water. NREL research confirmed last year that they’re less carbon-intensive than crystalline solar.
Mansfield noted an additional big advantage the cadmium telluride sector has right now: “It’s a thin-film technology that’s made in the U.S.”
“There’s a lot of advantage to that,” said Jane Harf, executive director for Green Energy Ohio. The companies are less vulnerable to foreign supply chain interruptions.
Even before the Covid-19 pandemic, U.S. companies in the crystalline silicon sector faced supply chain problems because of China’s global dominance in making the semiconductors they use. The country’s violation of anti-dumping rules triggered restrictive tariffs during the Trump administration. The Breakthrough Institute and others have also criticized China for using forced labor and other unfair labor practices.
Last June, President Joe Biden announced a 24-month reprieve from certain import duties for solar modules and cells coming from Malaysia, Cambodia, Thailand and Vietnam. The goal was to supply the U.S. solar market until domestic production of crystalline silicon semiconductors can ramp up.
A preliminary finding from the Commerce Department in December found some circumvention of the trade restrictions in all four Southeast Asian countries. Basically, companies were shipping Chinese products to the U.S. after just minor additional processing. That suggests imports for the crystalline silicon sector could become more challenging after June 2024, although the 2022 federal CHIPS Act aims to increase domestic production of semiconductors.
For now, all-domestic production means Toledo Solar is the only company in the rooftop solar market that can qualify for the full 40% tax credit under the Inflation Reduction Act, Bates said.
The cadmium telluride sector isn’t immune from potential supply chain issues. However, Mansfield said, the amount of semiconductor materials needed per panel is small. And better ways to refine the feedstocks could maximize their supply, she added.
“We’re essentially taking two byproducts from mining waste streams — cadmium and tellurium — and combining them into a stable compound,” Verma said. At the end of their useful life, more than 90% of the modules’ materials can be recovered.
Gains for Ohio
First Solar expects its Lake Township plant will provide 700 jobs in addition to the 1,600 jobs at its existing Ohio facilities. Plans call for the research and development facility to create another 200 jobs. Toledo Solar anticipates it will create more than 250 new jobs by 2027.
The two companies’ growth also attracts other businesses to Ohio. NSG Pilkington opened a new float glass line in Luckey in 2020, creating about 150 new jobs
And Ice Industries announced last year it will build a 150,000-square-foot plant in Bowling Green to make steel back rails for solar panels, providing about 120 new jobs.
The US-MAC consortium hopes to address ongoing challenges. There’s still a lot of room to improve cadmium telluride panels’ efficiency up to their theoretical limit, Mansfield said. Other elements of the panels can be enhanced as well.
The sector may face more competition from the crystalline silicon market as domestic semiconductor production ramps up or due to other advances. Other thin-film technologies could also pose competition. Researchers are also working on solar cells with stacked semiconductor layers that respond to different bandwidths of energy, Mansfield said.
Then there are perovskite solar cells, which can be printed or painted onto surfaces. A Feb. 16 study in the journal Science reported that perovskite solar cells with a bit of an added compound, called DPPP, maintained an efficiency of 23% over the course of two months until the study period ended.
Although multiple challenges remain, “perovskite solar cells may start making it to market in a few years,” said study co-author Yanfa Yan at the University of Toledo.
Politics could also affect how much future growth in the cadmium telluride sector stays in Ohio.
Solar energy is “still a political issue. And to me, it shouldn’t be,” Bates said. “It’s an economic issue.” In his view, state policymakers should appreciate and support Ohio’s leadership role in solar panel manufacturing.
“This is the center of the Western Hemisphere — full stop — for solar,” Bates said.
Kathiann M. Kowalski
Kathi is the author of 25 books and more than 600 articles, and writes often on science and policy issues. In addition to her journalism career, Kathi is an alumna of Harvard Law School and has spent 15 years practicing law. She is a member of the Society of Environmental Journalists and the National Association of Science Writers. Kathi covers the state of Ohio.
Made-in-Ohio solar panels benefit from federal incentives, supply chain politics
About two decades after cadmium telluride solar panels were commercialized in Ohio, the maturing technology is finding momentum thanks in part to its domestic manufacturing and supply chain.
Share this:
A once-novel solar power technology with Ohio roots is having a moment in the sun, along with two Toledo-area manufacturers.
Scientists had experimented with cadmium telluride solar panels in the lab since the 1950s, but the technology was commercialized just two decades ago after important groundwork by a pair of Ohio entrepreneurs who founded what would eventually become First Solar.
After years of fighting for a niche next to cheaper and more efficient crystalline silicon solar cells, cadmium telluride has recently closed the gap on cost and energy output. Cadmium telluride panels hold the largest worldwide market share among thin-film solar technologies, which use very thin layers of semiconductor material, versus thicker rigid crystalline silicon.
On top of technological advances, the sector is poised to benefit from ongoing supply chain politics and new federal climate change legislation that incentivizes domestic manufacturing.
Those trends are fueling a solar manufacturing boom in Ohio, where despite hostile state and local policies against solar farms, two cadmium telluride manufacturers have announced major expansions that promise to add hundreds of jobs in the coming years.
Get connected
Every morning, thousands of energy professionals turn to our newsletters for the day’s most important news. Sign up for free to get the latest delivered straight to your inbox.
First Solar plans to open its third Ohio factory later this year in Lake Township. That 3.3-gigawatt plant will be followed by a 1.3-million-square-foot research and development facility in Perrysburg, slated to open next year. Plans call for a fourth U.S. factory to open in Alabama in 2025, bringing the company’s total U.S. production capacity to roughly 10 GW.
Meanwhile, Toledo Solar, whose panels go mainly to commercial and residential users, is tripling its production capacity from 100 to 300 megawatts this year. Although the company is much smaller than First Solar, which targets the utility-scale market, “that’s a big deal for us,” said CEO Aaron Bates.
“The Toledo area, with its deep ties to the glass industry, was a natural incubator in the early years of our business,” said Kuntal Kumar Verma, chief manufacturing officer for First Solar. than 20 years later, northwestern Ohio “is home to a pool of thin-film solar manufacturing knowledge that is perhaps unparalleled anywhere in the world.”
Why Ohio?
The cadmium telluride solar sector’s origin story in Ohio starts with two superheroes of the glass industry.
Harold McMaster grew up as a farm boy in northwestern Ohio, and Norman Nitschke spent his boyhood in East Toledo. The two pioneered the manufacture and use of tempered glass — the stuff used for car windshields so it won’t break into jagged shards. They became co-founders of several companies, including Glasstech.
McMaster and Nitschke then began working on solar energy through Glasstech Solar. That work led to Solar Cells, Inc. Under McMaster’s leadership, the company developed the basic vapor deposition process for its cadmium telluride solar cells in 1997.
The process uses hot gas to crystalize a layer of cadmium telluride whose thickness measures roughly 3% of a human hair. That layer, glass and other materials make up the solar panel’s “sandwich.” Production takes less time than that for crystalline silicon panels, which represent the majority of solar panels used worldwide.
After the sale of a controlling interest in the company to an Arizona-based investment firm, Solar Cells, Inc. became First Solar in 1999 and opened its first manufacturing plant in Perrysburg.
Yet it took years before the cells’ efficiency improved enough to become competitive. In 2016, First Solar achieved an energy conversion efficiency of 22% in the lab. A 2019 study by company scientists and research at the National Renewable Energy Laboratory refined on that work, reducing the risk of instabilities that could lessen efficiency.
Toledo Solar chose the Toledo area when it started up in 2019, so it could capitalize on the knowledge base built up by First Solar and nearby universities. Starting elsewhere would have been “such a lift, and it would be so expensive,” Bates said.
Now cadmium telluride solar is a proven technology, and it’s competitive with crystalline silicon, said scientist Lorelle Mansfield at the National Renewable Energy Laboratory. “It’s in the field. It’s utility-scale. It’s out there, and it’s working well,” she said.
The cadmium telluride sector currently supplies roughly 40% of the U.S. utility-scale market and about 5% of the worldwide market, according to the U.S. Manufacturing of Advanced Cadmium Telluride Photovoltaics Consortium, or US-MAC. Members include various companies, universities and the National Renewable Energy Laboratory.
A Global Market Estimates report released in January projected that the global cadmium telluride market would grow at a compound annual rate of 12.5% from 2023 to 2028 as the energy transition continues.
Head-to-head
Although First Solar and Toledo Solar don’t compete with each other, they and other cadmium telluride companies in the global market do compete with crystalline silicon.
By late 2020, First Solar reported an average efficiency rate of 18% for its commercial modules. That’s at the low end of the 18% to 22% range the Department of Energy has reported for crystalline solar panels.
However, cadmium telluride can “deliver up to 4% more energy in hot climates and up to an additional 4% more energy in high humidity,” Verma noted. The theoretical efficiency of cadmium telluride panels is also higher — more than 30%. That’s because the semiconductor layer can respond to a wider range of light energy, Bates said.
Cadmium telluride panels also offer cost savings in production because they require less materials, less energy and less water. NREL research confirmed last year that they’re less carbon-intensive than crystalline solar.
Mansfield noted an additional big advantage the cadmium telluride sector has right now: “It’s a thin-film technology that’s made in the U.S.”
“There’s a lot of advantage to that,” said Jane Harf, executive director for Green Energy Ohio. The companies are less vulnerable to foreign supply chain interruptions.
Even before the Covid-19 pandemic, U.S. companies in the crystalline silicon sector faced supply chain problems because of China’s global dominance in making the semiconductors they use. The country’s violation of anti-dumping rules triggered restrictive tariffs during the Trump administration. The Breakthrough Institute and others have also criticized China for using forced labor and other unfair labor practices.
Last June, President Joe Biden announced a 24-month reprieve from certain import duties for solar modules and cells coming from Malaysia, Cambodia, Thailand and Vietnam. The goal was to supply the U.S. solar market until domestic production of crystalline silicon semiconductors can ramp up.
A preliminary finding from the Commerce Department in December found some circumvention of the trade restrictions in all four Southeast Asian countries. Basically, companies were shipping Chinese products to the U.S. after just minor additional processing. That suggests imports for the crystalline silicon sector could become more challenging after June 2024, although the 2022 federal CHIPS Act aims to increase domestic production of semiconductors.
For now, all-domestic production means Toledo Solar is the only company in the rooftop solar market that can qualify for the full 40% tax credit under the Inflation Reduction Act, Bates said.
The cadmium telluride sector isn’t immune from potential supply chain issues. However, Mansfield said, the amount of semiconductor materials needed per panel is small. And better ways to refine the feedstocks could maximize their supply, she added.
“We’re essentially taking two byproducts from mining waste streams — cadmium and tellurium — and combining them into a stable compound,” Verma said. At the end of their useful life, more than 90% of the modules’ materials can be recovered.
Gains for Ohio
First Solar expects its Lake Township plant will provide 700 jobs in addition to the 1,600 jobs at its existing Ohio facilities. Plans call for the research and development facility to create another 200 jobs. Toledo Solar anticipates it will create more than 250 new jobs by 2027.
The two companies’ growth also attracts other businesses to Ohio. NSG Pilkington opened a new float glass line in Luckey in 2020, creating about 150 new jobs
And Ice Industries announced last year it will build a 150,000-square-foot plant in Bowling Green to make steel back rails for solar panels, providing about 120 new jobs.
The US-MAC consortium hopes to address ongoing challenges. There’s still a lot of room to improve cadmium telluride panels’ efficiency up to their theoretical limit, Mansfield said. Other elements of the panels can be enhanced as well.
The sector may face more competition from the crystalline silicon market as domestic semiconductor production ramps up or due to other advances. Other thin-film technologies could also pose competition. Researchers are also working on solar cells with stacked semiconductor layers that respond to different bandwidths of energy, Mansfield said.
Then there are perovskite solar cells, which can be printed or painted onto surfaces. A Feb. 16 study in the journal Science reported that perovskite solar cells with a bit of an added compound, called DPPP, maintained an efficiency of 23% over the course of two months until the study period ended.
Although multiple challenges remain, “perovskite solar cells may start making it to market in a few years,” said study co-author Yanfa Yan at the University of Toledo.
Politics could also affect how much future growth in the cadmium telluride sector stays in Ohio.
Solar energy is “still a political issue. And to me, it shouldn’t be,” Bates said. “It’s an economic issue.” In his view, state policymakers should appreciate and support Ohio’s leadership role in solar panel manufacturing.
“This is the center of the Western Hemisphere — full stop — for solar,” Bates said.
Kathiann M. Kowalski
Kathi is the author of 25 books and more than 600 articles, and writes often on science and policy issues. In addition to her journalism career, Kathi is an alumna of Harvard Law School and has spent 15 years practicing law. She is a member of the Society of Environmental Journalists and the National Association of Science Writers. Kathi covers the state of Ohio.
What Are Cadmium Telluride (CdTe) Solar Panels? How Do They Compare to Other Panels?
The Cadmium Telluride (CdTe) solar technology was first introduced in 1972 when Bonnet and Rabenhorst designed the CdS/CdTe heterojunction that allowed the manufacturing of CdTe solar cells. At first, CdTe panels achieved a 6% efficiency, but the efficiency has tripled to this day.
Companies like Kodak, Monosolar, AMETEK, and many others have researched CdTe technology. Nowadays, CdTe technology is the most popular thin-film solar panel technology and it is the preferred option by the top 10 manufacturers of thin-film solar panels in the world.
In this article, we will do a deep dive on CdTe solar panels and everything related to this technology. We will explain the materials and manufacturing process for these thin-film solar panels, possible applications, and compare them to other technologies.
What is a Cadmium Telluride (CdTe) solar panel?
Cadmium Telluride solar panels are the most popular thin-film solar panels available in the market. These represent around 5% of the solar panels in the world market and come only second to crystalline silicon panels.
CdTe thin-film solar panels are so popular because they are easy and not expensive to manufacture, making them ideal for investors. CdTe panels have an average efficiency of 19%, but laboratory tests performed by First Solar, have achieved record efficiencies of 22.1% for CdTe solar cells.
Understanding CdTe thin-film solar panels, is vital to know the true advantages and possible applications for these thin-film solar panels. In this section, we will explain the materials, manufacturing process, and other interesting details about CdTe solar panels.
Materials used in CdTe thin-film solar cells and panels
CdTe cells are made by using semiconductors that optimize the efficiency of transforming solar radiation into electricity. CdTe solar cells are made by using p–n heterojunctions containing a p-doped Cadmium Telluride layer and an n-doped Cadmium Sulfide (CdS) layer, which may also be made out of magnesium zinc oxide (MZO).
While these materials are cheap, they can also be toxic and pollutant when improperly disposed of. Greenpeace has warned about the toxicity and contamination levels of these materials, stating that CdTe panels contain 6g/m 2 of toxic metals and they produce cadmium emissions equivalent to 0.5G/GWh. There are also several health concerns attached to these materials.
Aside from materials used for CdTe cells, there are other materials required to make CdTe thin-film solar panels. These materials are:
The manufacturing process of CdTe thin-film solar panels
CdTe thin-film solar panels are comprised of three main parts, having a layer for the semiconductor, one for the protection, and one for the conduction. These parts are:
Each of these sections is vital for CdTe thin-film solar panels. The manufacturing process is made through a different set of methods called deposition techniques. The different types of techniques used are sputtering, chemical spray pyrolysis, electrodeposition, or close vapor transport (CVT). The materials used in each of these parts of the CdTe thin-film solar panels are the following:
Photovoltaic material
The photovoltaic material is the part of the CdTe thin-film solar panel that converts solar radiation into DC energy. This is manufactured by creating a p–n heterojunction, this semiconductor requires the deposition of a layer of CdTe for the p-doped section and one of CdS or MZO for the n-doped section.
Conductive sheet
The conductive sheet allows the DC energy to flow between solar cells, increasing the voltage and allowing for the connection of CdTe panels into photovoltaic (PV) systems. These layers require the deposition of a metal layer or carbon paste, introducing copper (Cu) to create conduction in the panel.
Protective layer
Photovoltaic layers tend to be very fragile, which is why thin-film solar panels require a protective layer. Instead of using an aluminum frame and tempered glass, this layer known as the Transparent Conductive Oxide (TCO) layer, is made by depositing SnO2:F or a similar material. The TCO layer is where the CdTe absorber is deposited, allowing the solar cell to be fully protected.
CdTe solar panels vs. Other types of thin-film panels
CdTe solar panels are not the only thin-film panels in the market. Aside from these, there are three main options available:
- Amorphous silicon (a-Si) solar panels
- Copper indium gallium selenide (CIGS) solar panels
- Gallium arsenide (GaAs) solar panels
These thin-film solar panels and CdTe have many differences. For a better understanding of these, we will compare each thin-film solar panel against CdTe panels, considering materials, efficiency, application, and other aspects.
Amorphous silicon (a-Si) vs. CdTe solar panels
A-Si thin-film solar panels are less efficient than CdTe panels, achieving a 6-7% efficiency. Since a-Si solar panels are cheaper and less toxic than other options, they have become the second most popular option for thin-film solar panels.
The a-Si solar panels are regularly used in small-scale applications. Recent developments show promising results for these panels in the future since they have the potential to be integrated into clothing.
Producing a-Si solar panels is cheaper and easier than CdTe panels because they only require a fraction of the silicon that other panels do. These are manufactured through an evaporation method, allowing for the fabrication of a thin semiconductor layer that is placed on glass or stainless steel.
Copper indium gallium selenide (CIGS) vs. CdTe solar panels
CIGS solar panels are less toxic than CdTe, but they still represent moderate toxicity for respiratory tracks in humans. These thin-film solar panels are less efficient than CdTe, achieving a 12-14% efficiency, but laboratory studies have recorded excellent efficiency results of 20.4%.
While production costs for CIGS thin-film solar panels are not as cheap as CdTe, new manufacturing processes with lower costs are being developed. These panels are usually manufactured through sputtering, evaporation, electrochemical depositions, and several other processes.
CIGS thin-film solar panels are usually used in facades and Windows since they are very easy to install and have a pretty decent efficiency. These thin-film solar panels are considered for space applications.
Gallium arsenide (GaAs) vs. CdTe solar panels
GaAs thin-film solar panels can achieve an efficiency of 28.8%, making them the most efficient and durable thin-film solar panels available, but they are also the most expensive. GaAs is slightly less toxic than CdTe, but it is still the second most toxic semiconductor in the list.
The manufacturing process for GaAs is more expensive and complex than CdTe. These panels require a growing process on a doped substrate, afterwards, they are coated with anti-reflecting and metallization materials. In the future GaAs thin-film, solar panels could end up costing much less.
GaAs solar panels are rarely sold in the market. These thin-film panels are more frequently used for spacecraft, military vehicles, space missions, and other specialized applications.
CdTe solar panels vs. Crystalline silicon solar panels (Pros and cons)
CdTe solar panels and crystalline silicon solar panels are very different technologies. To know which one is the best technology, we will compare them, highlighting and considering the pros and cons of each one for analysis.
- Monocrystalline silicon (c-Si)
- Multi-crystalline (mc-Si)
- Polycrystalline silicon (pc-Si)
One main advantage of CdTe technology is the low cost of manufacturing. CdTe panels can be found at low of 0.46/Watt, which is 70% cheaper than the cost for crystalline panels. Another strong advantage of CdTe technology is that it is less affected by strong changes in temperatures, delivering a constantly higher voltage in PV systems.
While crystalline solar panels are more efficient than CdTe (making them better for residential markets), this does not mean that they are more suitable for all types of installations. In some industrial applications in hot weather, solar farms with CdTe panels can have the potential of delivering a higher power output than crystalline silicon solar panels.
CdTe panel application: When to use CdTe solar panels?
Even though CdTe panels are not always the best option for residential applications, these panels are quite versatile for commercial and industrial applications.
CdTe solar panels are 1-6% less efficient than crystalline modules, but they have 70% lower. These low make CdTe an excellent technology for solar farm installations where space is not a problem. These solar farms could deliver cheaper electricity than fossil fuel power and even crystalline silicon solar farms.
Since CdTe thin-film solar panels are more adaptable to different structures, they can be installed in different aircraft and be used for space applications. Unmanned aerial vehicles with this technology in space, can be highly benefited from CdTe panels since they are cheap, shape-adaptable, and very lightweight.
CdTe thin-film technology is very promising. These panels are excellent for industrial and commercial applications, and they could even be installed in the future at the roof of electric vehicles (EVs) since they can be easily installed at odd structures like the hood or roof of a car.
Final words
There should not be any doubts regarding the popularity of CdTe technology as the best thin-film solar panel. These modules are cheap, lightweight, resistant, have high efficiency, and are easy to manufacture, making them excellent for a wide variety of applications.
While CdTe solar panels are still not widely used in residential applications, they are still used in the commercial and industrial sectors.
The future of CdTe thin-film solar panels is very promising. These panels are the preferred option for space aircraft, some solar farms, and we could even see them on the roofs of EVs in the future.