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Most Efficient Solar Panels Of 2023 (Guide). Silicon solar module

Most Efficient Solar Panels Of 2023 (Guide). Silicon solar module

    Most Efficient Solar Panels Of 2023 (Guide)

    Samantha covers all topics home-related including home improvement and repair. She previously edited home repair and design content at The Spruce and HomeAdvisor. She also has hosted videos on DIY home tips and solutions and launched multiple home improvement review boards staffed with licensed pros.

    We earn a commission from partner links on Forbes Home. Commissions do not affect our editors’ opinions or evaluations.

    Installing the solar panels for your home is an excellent way to conserve energy and lower utility bills. However, it’s important to understand the differences in the fabrication of solar panels in order to choose the most efficient solar panels for your commercial or residential installation. For those looking to install solar at home, we’ve searched for and found the best solar companies for consideration.

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    How Efficient Are Solar Panels?

    The efficiency of solar panels is determined by the amount of sunlight reflected on the panels’ surface, which is then transformed into electrical or thermal energy. Previously, the average efficiency of solar panels was around 15%, but thanks to advancements in photovoltaic technology, the efficiency of solar panels is currently between 15% and 22%. High-efficiency solar panels can even reach nearly 23%. As a result, 370W is the typical power rating of a panel, an improvement from 250W. Two factors go into determining solar panel efficiency: photovoltaic (PV) cell efficiency and total panel efficiency.

    Panel Efficiency

    PV cell efficiency comes as the result of the cell design and silicon type, while cell layout and configuration along with the solar panel size are the basis for total panel efficiency.

    Cell Efficiency

    Total panel efficiency is determined by the maximum power rating under standard test conditions divided by the total area of the panels (in meters).

    Most Efficient Solar Panels

    While the most efficient readily available panels all share efficiency percentages above 20%, Canadian Solar’s HiHero series panels are tied with SunPower for the highest efficiency rating at 22.80% under optimal conditions.

    However, the Canadian Solar HiHero 445 H-AG solar panel has a temperature coefficient of 0.26%. Compared to SunPower’s coefficient of 0.29%, the HiHero edges out its competition when the temperature rises over 77 degrees Fahrenheit.

    most, efficient, solar, panels, 2023, guide
    Canadian Solar HiHero High Efficiency Heterojunction (HJT) Cell Module 445H-AG -0.26 22.80%
    SunPower 420-440W Residential AC Module M-Series: M440 -0.29 22.80%
    Q Cells Q.Peak Duo Blk ML-G10 £410.00 -0.27 20.90%
    REC Solar REC Alpha Pure-R REC430AA PURE-R -0.26 22.30%
    Panasonic Solar EverVolt™ Series EVPV410H -0.26 22.20%
    Silfab SILFAB Elite SIL. 380 BK 0.38 21.40%
    Residential panels with data correct as of April 2023

    Canadian Solar

    Canadian Solar offers consumers ten solar panel model series. Its lineup of HiKu Mono PERC panels on one end of the spectrum provides up to 425 watts at 20.9% efficiency, while at the other end, the company’s BiHiKu7 models start at 580 watts and continue through six more wattages to reach a whopping 610 watts.

    However, the company’s most efficient solar panel is its HiHero 445 H-AG model, which features a 445-watt capacity at a 22.8% efficiency rating and a 0.26% coefficient rating.


    SunPower offers three lines of residential panels along with components and energy storage systems. The company’s M series solar panels consist of five models that range in efficiency from 21.7% in the M420 model to the highest in our review, the M440, with a 22.8% rating.

    SunPower’s two other series are the X and U lines. The X lineup uses the company’s own Maxeon technology and ranges from 21.2% to 22.7% in efficiency. The U series is SunPower’s most recent budget-friendly addition that steers away from using Maxeon panels but still comes with similar warranty protections.

    Q Cells

    Q Cell’s residential panel selection includes several models in the Q-Peak Duo BLK ML-G10 and the Q-Peak Duo BLK-G10 lines. The BLK-G10 series features panels that range from 350W to 370W with efficiency ratings from 19.5% to 20.6%.

    The ML-G10 is Q Cell’s most recent lineup featuring higher watt ratings and slightly higher efficiency. Panels in the series include a 385W model with 19.6% efficiency and five more models. The most powerful one in the series is a 410-watt panel with 20.9% maximum efficiency and a temperature coefficient of 0.27%.

    REC Solar

    REC Solar provides five solar panel series to choose from—Starting with its 360W to 375W N-Peak 2 series and increasing in wattage capacity through each series. Its most powerful and efficient panel is the company’s Alpha Pure-R, featuring 430 watts of power rated at 22.3% efficiency with a coefficiency percentage of 0.26.

    Panasonic Solar

    Among numerous industries that Panasonic is involved in, the company offers a selection of 15-panel models in six series variations in its solar energy sector. The collection, called Evervolt, consists of residential solar panels with watt ratings from 350 to 410.

    The highest wattage Evervolt H Series Solar Module offers 410 watts with a 22.20% efficiency rating and a 0.26% temperature coefficient.

    Silfab Solar

    Silfab’s solar panel offerings include two residential series, Silfab Prime and Silfab Elite. Models available in both series have efficiency ratings topping out at 21.4%. The company’s most powerful panel, the SIL-410 BG churns out up to 410 watts with a coefficiency rating of 0.377%

    How You Can Check Solar Panel Efficiency

    Monitoring your solar panels’ performance and efficiencies allows you to compare calculations to keep an eye out for panel degradation, or notice sudden drops in efficiency that could indicate a problem with the system.

    To calculate the efficiency of an individual panel, you’ll need to measure the surface dimensions and determine the total production area in meters squared. You’ll also need the current power production amount in kilowatts.

    There are several ways to determine the kilowatt output. If you’re looking for the panel’s potential, simply use the panel watt rating for the calculation and divide by 1,000. For more accurate testing, take the wattage number from your solar meter or use a multimeter to measure volts and amps. Multiply the two results to arrive at the total watts. Divide the watts by 1,000 to reach the kW measurement.

    With those two numbers, divide the panel output by the total area of the solar panel surface in square meters. Multiply the result by 100. The total is your current efficiency rating of the panels you’re testing.

    For example, a solar panel that measures 182 cm by 106 cm has a surface area of 1.82 m x 1.06 m or 1.93 square meters. If the panel is producing 400 watts or 0.40 kW. Dividing 0.40 by 1.93 equals 0.207. Multiply by 100 for an efficiency reading of 20.7%.

    Efficiency by Solar Panel Type

    There are three types of solar panels that are most often used in commercial or residential installations: monocrystalline, polycrystalline, and thin-film. Here is a brief explanation of each, as well as for what applications they are most useful:


    Monocrystalline solar panels are often touted as the most efficient option and are often installed for larger energy systems in commercial and residential properties. However, panel sizes do vary; therefore, monocrystalline can be used in smaller installations as well.


    • Made out of silicon with a high purity rating, boosting their efficiency to 15% to 23%
    • Don’t require as much space as polycrystalline and thin-film panels
    • Monocrystalline panels can last upwards of 25 years due to the stable and inert properties of the silicon


    • Price point is high because of their complex construction
    • Not a good choice for cold-weather climates, as snowfall can damage the solar cells and cause the system to fail.

    Monocrystalline brands: SunPower, LG, and Panasonic


    Like the name suggests, polycrystalline solar panels are constructed from multiple pure silicon crystals that are melted together. crystals aren’t always better, though. Polycrystalline panels are actually less efficient than their monocrystalline counterparts. They are, however, made in a variety of power settings ranging from 5W to 250W and higher, making them a good choice for both small and large-scale installations.


    • Process to create them is simpler, so they are less expensive than monocrystalline
    • Less waste after the melting process, making them better for the environment
    • Durable and long-lasting, just like monocrystalline solar panels, so they are a good choice for budget-minded homeowners


    • Lower efficiency (13% to 17%) because the silicon used to make them is lower in purity.
    • Take up more space to produce the same level of power as that of monocrystalline cells.

    Polycrystalline brands: TrinaSolar and YingliSolar

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    Though they are lightweight and easy to move, thin-film PV cells—which are not made of silicon—are the least efficient type of solar panel. Use them only for installation that won’t need to produce too much power; flexibility and portability are the two top factors with these.


    • Easier and less expensive to produce
    • Excellent for solar transportation applications, such as panels that are installed on bus rooftops and refrigeration for cold-storage trucks


    • Not a good choice for rooftops, as they require a large space to harness enough solar power for energy output.
    • Weaker so they break down more quickly than crystalline panels. Only short warranties are available for thin-film panel installations, which is something homeowners especially should consider depending on how long they plan to stay in their homes.

    Thin-film brands: Stion and Solopower

    Factors That Impact Solar Efficiency

    Several things can affect solar panels’ efficiencies, such as the type of solar panel, the inverter efficiency, thermal cycling, etc. Here are some factors to consider before purchasing a solar panel system:

    Solar Panel Types

    When figuring out which type of solar panel is right for your home, the first thing to do is to get acquainted with each type, its construction and its efficiency:

    • Monocrystalline Solar Panels: The most popular and most efficient type of solar panels, monocrystalline solar panels, are popular amongst residences and businesses. They are made of individual pure silicon crystal and can generate between 300 and 400 (sometimes even more) watts of power each.
    • Polycrystalline Solar Panels: Polycrystalline panels are made from several pieces of silicon that are separated into fragments and melted together. They are slightly less expensive but also less efficient than monocrystalline solar panels.
    • Thin-Film Solar Panels: Thin-film solar panels can be made of three different materials: Amorphous Silicon (a-Si), Cadium Telluride (CdTe) and Copper Indium Gallium Selenide (CIGS). Each type of thin-film solar panel is less expensive than both crystalline panels but is also less efficient.

    Sunlight Hours

    While solar panels can generate electricity in various light conditions, even on cloudy days, their efficiency rates drop dramatically during hours with little light available. Generally, about four hours per day of direct sunlight is necessary to achieve the optimum performance of your solar panel array.

    However, during the remaining daylight hours, when sunshine is present but not direct, your solar panels can still generate substantial electrical power. The same is true of overcast days.

    The total number of hours of any kind of sunlight per day directly affects the overall efficiency of your panels in the short term. There are no long-term effects to solar panels that don’t receive an optimal amount of sunlight daily.

    Inverter Efficiency

    The inverter is what converts general Direct Current (DC) to Alternating Current (AC) electricity, which is what your home runs on. Most inverter’s conversion efficiency is around 97% to 99%, so the energy loss is relatively minor.

    Temperature Coefficient

    Solar panel efficiency ratings are measured and recorded under laboratory conditions called Standard Test Conditions or STC. The lab conditions include measurements taken at 25 degrees Celsius (77F). The temperature coefficient rating for solar panels measures the percentage of the panel’s efficiency loss when its surface rises above that temperature.

    For each degree Celcius that the panel’s temperature rises above 25, the panel’s efficiency will lessen by the coefficient rating percentage.

    For example, SunPower’s most powerful solar panel, the M440 produces a maximum output of 440 watts under ideal conditions at 25 degrees Celsius. Its efficiency rating at that temperature is 22.8%. The panel has a temperature coefficient rating of 0.29%.

    When the panel temperature increases by 10 degrees Celsius (50F), which isn’t uncommon under hot sunlight, its efficiency will decrease by 2.9%, meaning its overall efficiency drops below 20%. Essentially, it produces less power when it’s hot.

    Damp Heat

    Solar panel damp heat testing puts a subject solar panel through a rigorous test in which it’s sealed in a chamber kept at 85 degrees Celsius and 85% humidity for 1,000 hours. The test aims to recreate and accelerate the harsh conditions that the product will experience over several years of direct exposure to the elements.

    While damp heat testing doesn’t directly measure the effects of weather on a panel’s efficiency, the process tests the unit’s integrity related to delamination and corrosion, which, in turn, affect the panel’s overall efficiency.

    Thermal Cycling

    Thermal cycling tests your solar panel to see if it can withstand a wide temperature range. Solar panel components can expand and contract during Thermal Cycling, which may affect their efficiency.

    Solar Panel Orientation

    South-facing roofs are ideal for generating electricity with solar panels. West-facing roofs are the next best option, and east-facing roofs are next. If you have a north-facing roof, you may want to reconsider. West and east-facing panels will generate up to 15% less energy than a south-facing array while north-facing panels can lose as much as 20%.

    Identifying the prime installation angle towards the sun is essential to optimize solar panel performance. The exact angle degree varies based on latitude but generally lands between 30 and 45 degrees. The installation angle affects how much time per day the panel receives direct sunlight.

    The installation angle is most impactful during winter when the sun is lower on the horizon. Correct orientation and angle during winter can yield around 50% more energy than panels installed without the same consideration.

    Environmental Factors That Impact Solar Efficiency

    In addition to the typical factors, your environment is also something to consider before purchasing a solar panel system. Environmental factors such as average temperature, weather conditions and even dust and dirt build-up also impact solar efficiency.


    Solar panels work best at about 77°F, with peak efficiency between 59°F and 95°F. However, when the surface temperature of your solar panels gets higher than 149°F, solar panel efficiency can decline.


    The color of the back sheet that protects the panels can also affect efficiency. For example, while black might look more attractive for a protective back sheet, the color absorbs more heat. This results in higher temperatures and, therefore, a reduction in the total conversion efficiency, so other colors like dark blue, green or even patterns might be a better option for your solar panels.

    Extreme Weather Conditions

    Anything that stands between the sun and your solar panels reduces the amount of solar energy your system produces. Therefore, extreme weather conditions such as snow, wind, rain and hail can potentially affect your solar panel’s efficiency.

    Since snow accumulates onto the surface of your solar panels, the sun cannot penetrate the panels, which will ultimately affect the efficiency of your system.

    Since the wind could potentially cool your solar panels down, the wind can make them more efficient as long as the sun is still shining on them.

    Rain does not affect your solar panel efficiency; however, rain clouds could affect how much sun reaches them. However, constant rainstorms help keep layers of dirt and dust from covering the panels and blocking the light, which could decrease solar energy production.

    Unlike snow and rain, a hail storm can present slight problems for your solar panels. Although solar panels have been tested to withstand hail-like conditions, there is a chance of solar panel damage from a hail storm.

    Dust and Grime Build Up

    As time passes, your solar panels are bound to have some dust and grime build up due to the elements. If there is a layer of dust and grime on your solar panels, the sun will not be able to effectively reach the panels, causing a lapse in efficiency until the panels are cleaned.

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    Why Is Solar Panel Efficiency Important?

    Solar panel efficiency is measured by the percentage of sunlight that hits your panel and is converted into usable electricity. Therefore, efficiency is most important when roof space is limited.

    For instance, if you have limited roof space and cannot fit as many solar panels on your roof as you would like, it may make sense to pay more to install higher-efficiency panels to absorb as much sunlight as possible.

    However, lower-efficiency panels will produce the same energy as high-efficiency ones, but they’ll require more to do so and more space. Therefore, lower-efficiency panels can cover your electricity use and help you save money if you have the space to house them.

    The amount of power a panel with 15% efficiency can create can be as much as 100 watts less than a panel of the same size that can achieve 22% efficiency. In an average residential solar setup, the home could require up to eight additional 15% solar panels to generate the same power as 20 units at 22%.

    Why Aren’t Solar Panels 100% Efficient?

    A panel with 100% efficiency can transform all the light that hits the panel into electrical energy. However, since solar panels cannot absorb energy from the entire solar spectrum, they cannot convert sunlight into electricity with 100% efficiency. Specific wavelengths of light are reflected off the solar panels or lost altogether.

    What to Consider When Installing Solar Power Panels


    Solar panels can be costly upfront, which is why many homeowners do not take the decision to go solar lightly. The Center for Sustainable Energy reports that the installation can cost, on average, between 15,000 and 25,000. Polycrystalline solar panels are considered the most cost-effective choice in solar panel installations, but it depends on the type of panels and how many are needed for installation.

    While your initial investment in solar panels can be recouped over the years, it might take longer for you to see back your money based on a number of factors, including energy usage and weather conditions; the latter might affect solar panel functionality.

    most, efficient, solar, panels, 2023, guide


    Solar-powered energy, not surprisingly, is more efficient in places where there is more sun exposure. Residential and commercial buildings in Southern California, for example, would likely reap the benefits of solar power more so than those in the cloudy Pacific Northwest. Still, even places that aren’t the sunniest can benefit from solar power, as cooler temperatures will cause the panels to create more power.

    Energy Usage

    If your energy bills are high, then it makes sense to install solar panels to reduce costs and to earn back the initial investment over time. However, if your energy usage is minimal, solar panel installation might not be worth the expense. It is also important to note that top efficiency is only achieved in top conditions and only at the beginning of the panel’s lifetime of use. As the solar panels age and are exposed to the elements, they will begin to perform less efficiently.

    Solar Installation Companies

    The company you choose to install your solar energy system is a crucial decision. While some installers use several solar panel and component manufacturers, many install just one or two brands. Ensure the installation company you choose is willing to install the solar panel brand of your choice and can service the system when necessary.

    Solar Incentives

    The federal residential solar tax credit allows homeowners to deduct 30% of the cost of their installed solar energy system from their taxable income for the year. However, that’s just one of several incentives that may be available depending on your location. Look for local, state and regional incentives as well. Your solar installation company should be well-versed in helping you discover these benefits.

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    THIS IS AN ADVERTISEMENT AND NOT EDITORIAL CONTENT. Please note that we do receive compensation for any products you buy or sign up to via this advertisement, and that compensation impacts the ranking and placement of any offers listed herein. We do not present information about every offer available. The information and savings numbers depicted above are for demonstration purposes only, and your results may vary.

    Frequently Asked Questions (FAQs)

    What is the highest efficiency solar panel?

    Currently, the highest recorded solar panel efficiency rating took place in a lab and is rumored to have reached over 40% efficiency. However, in more practical conditions, the most highly efficient solar panels available to homeowners is Canadian Solar’s HiHero 445 H-AG model.

    What is the most efficient type of solar panel?

    Monocrystalline solar panels are often considered the most efficient solar panel option. Therefore, they are typically installed for larger energy systems in commercial and residential properties.

    How does increased energy efficiency benefit you?

    Increased energy efficiency in solar panels has several benefits for homeowners.

    • Potentially fewer solar panels to purchase and maintain
    • Highly efficient solar panels produce more power in direct and indirect sunlight.

    What solar panel type has the highest efficiency?

    Monocrystalline solar panels are often considered the most efficient solar panel option. Therefore, they are typically installed for larger energy systems in commercial and residential properties.

    most, efficient, solar, panels, 2023, guide

    How many solar panels do you need?

    With a home of roughly 1500 square feet, it is estimated that 15 to 18 solar panels will be needed.

    Can you DIY a solar panel installation?

    It’s tempting to save money and install solar panels yourself, especially if you have numerous successful DIY projects under your belt. But installing solar panels is a project that is best left to the pros. Depending on the type of panel you choose, installation might require complex configurations that are otherwise difficult to install correctly without the training experience.

    Additionally, professional installation might be required to uphold the warranty. As with many projects, getting a professional to install a solar energy system means that it will be done right the first time so that you can begin reaping the benefits of it immediately.

    How long will it take to recoup the cost of solar panels?

    This answer will vary depending on a variety of factors, including the initial expense of the solar panel system, the amount of energy incentives and electricity usage. On average, though, it takes homeowners six to 10 years to recoup their initial investment.

    How long do solar panels last?

    Solar panels have an average lifespan of 25 to 30 years. However, they can last as many as 50 years. The longevity of solar panels depends on the weather conditions where they are installed, as snow, wind and debris from storms can affect their operation.

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    Perovskites can make solar panels more efficient than silicon alone

    But will their remarkable performance in the lab ever translate into real market momentum? Caelux and other tandem-solar startups are betting the answer is yes.

    Startup Caelux is betting that its ​ “ tandem” solar technology, which combines perovskite photovoltaics with market-dominating silicon, will result in more efficient solar panels — and the company recently received a 12 million investment from Indian conglomerate Reliance New Energy to commercialize this new approach. Vinod Khosla, no stranger to next-generation solar, is also an investor in the Caltech spinout, which is based in Pasadena, California.

    Tandem solar startups like Caelux place a light-absorbing layer made from perovskites, a class of crystalline materials, atop a conventional silicon cell. This dual-material architecture has the potential to break through the efficiency barrier of single-junction silicon because of the different wavelength sensitivities of silicon and perovskite materials.

    In the last 10 years, the average conversion efficiency of commercial wafer-based silicon modules has increased from about 15 percent to more than 20 percent and is forecast to reach efficiencies of 23 to 24 percent by the end of the decade, approaching the practical limits of this technology.

    With a perovskite layer added, ​ “ you’re going to see a 20 percent to 30 percent relative efficiency boost,” Caelux CEO Scott Graybeal told Canary Media. ​ “ So you’re talking about modules that will come out at 27 percent to 29 percent efficiency.”

    With more efficient solar panels, more electricity could be produced from a plot of land or a rooftop, making solar power — already the cheapest form of electricity in history — even more cost-effective.

    But a commercially viable, higher-efficiency non-silicon solar module has proven elusive. Over the last decade, tens of billions of dollars in venture and corporate funding has been spent chasing that goal, most of it for naught.

    Pros and cons of perovskites

    Scientists have been researching perovskite technology for years, but recent advancements are raising excitement about the potential for tandem modules at commercial scale.

    Earlier this month, researchers in the Netherlands announced a breakthrough with a perovskite-silicon tandem cell that reached 30 percent efficiency, which they called ​ “ a big step in accelerating the energy transition.” Other research laboratories have been announcing milestones as well.

    Perovskites have some promising traits:

    • The rate of Hero-experiment efficiency gains for perovskite materials and tandem structures has been phenomenal, outpacing other technologies.
    • Perovskites can be produced from earth-abundant materials.
    • Perovskites have the potential to be recycled.
    • Perovskite cells can be manufactured using lower-cost and more forgiving ink-based printing processes rather than complex semiconductor equipment.
    • The low-temperature processes used in manufacturing perovskites mean that energy payback times are shorter than for state-of-the-art PV technologies, according to Graybeal.

    But questions loom about perovskite lifetimes, degradation and stability.

    Demonstrating the long-term reliability of a tandem cell will take years, as will gaining a good understanding of perovskites’ failure modes and degradation paths. Perovskites will have a ​ “ slightly higher degradation rate than silicon” in the material’s early days in solar tandem modules, according to Graybeal.

    Get Caught Up

    Can the US manufacture enough solar panels to meet its surging demand?

    “ To be competitive in the marketplace, perovskite’s long-term durability must be tested and verified,” the U.S. Department of Energy said in 2020 when it announced 20 million in funding to advance perovskite solar photovoltaic technologies. Earlier this year, pv magazine noted that effective testing of perovskites is not yet on track: ​ “ Much testing is required, yet today’s tests are geared toward commercialized PV technologies (Si, CdTe, etc.) and are unlikely to capture all the failure modes relevant to perovskite modules in the field.”

    Working with, not against, silicon

    Competing against silicon is an uphill battle. than 200 gigawatts of solar power capacity will be deployed around the world this year, the vast majority of it in the form of silicon PV panels. Silicon’s long-term behavior and failure modes are already well understood, allowing module producers to offer 25.year guarantees.

    So for now, most perovskite solar companies are focused on producing tandem products that include silicon, not on head-to-head competition.

    While Graybeal does envision a future that includes pure perovskite modules, he acknowledges that the only way to deploy this technology at scale ​ “ is by combining perovskites with silicon solar” and complementing the existing PV manufacturing infrastructure.

    “ We consign glass [from customers] that they’ve already spec’d and qualified for their product. [We] put our proprietary material stack on that glass and then move it along to their module manufacturing operations,” Graybeal explained. He said the perovskite factory has to be close to a major logistics node and close to a customer’s module manufacturer in order for this to work, ​ “ and that’s been part of our plan. As much as the perovskite is part of our product portfolio, the ability to ramp and scale factories is also a competency that we’re developing.”

    Caelux investor Reliance New Energy, a subsidiary of Reliance Industries, India’s largest private-sector company, is entering a strategic partnership with the startup. Reliance New Energy is building a global-scale solar factory in Jamnagar, Gujarat, where it plans to incorporate perovskites into some of the modules it produces. According to Graybeal, the partnership means that ​ “ Reliance has essentially sold out our factory for the first year and a half of its operation — and that’s more important than the cash investment.”

    “ If you’re going to get any product into the market, you have to start producing in volume. We can’t all sit around and play with our two-inch-by-two-inch devices — it will take us 10 years to get to the next technological leap forward,” said the CEO. He added, ​ “ Tier 1 manufacturers are going to put us through our paces before they’re going to put their name on a module with our technology on it.”

    With typical entrepreneurial fervor, the CEO said he expects Caelux’s tandem module, along with a 25.year warranty, to launch into the marketplace in the second half of 2024.

    Perovskite contenders

    Caelux is not the only company in this space. Canary reported last year on CubicPV, formed from the merger of U.S. wafer maker 1366 Technologies and Hunt Perovskite Technologies, which is also working on tandem modules. That article listed other startups that are developing perovskite and tandem solar materials using a range of device architectures and manufacturing processes.

    • BlueDot Photonics uses​“continuous flash sublimation production” techniques to improve the efficiency of perovskite photovoltaics.
    • Energy Materials Corp. is developing a roll-to-roll perovskite deposited on a flexible substrate.
    • Microquanta Semiconductor is building panels from glass-packaged perovskites.
    • Oxford PV is developing perovskite-on-silicon tandem solar cells and modules.
    • Saule Technologies is developing an inkjet printing technique for manufacturing perovskite solar cells packaged on bendable plastic.
    • Swift Solar stacks perovskite solar cells to make tandem cells and can deposit its perovskite layers on flexible substrates and foils.
    • Tandem PV aims to monolithically print thin-film perovskites on glass panels and mechanically stack them on top of silicon cells.
    • Wuxi UtmoLight claims to have achieved a Japan Electrical Safety Environment Technology Laboratories–certified 18. 2 percent efficiency for its large-area 756 cm² perovskite solar module. The Chinese company says that it is conducting trial runs on its 150.megawatt module production line, which it claims is the ​ “ world’s largest” for perovskite solar.

    Other very early-stage perovskite startups include Beyond Silicon, MujiElectric, SoFab Inks and Verde Technologies.

    But for now, perovskites still have zero percent of the global solar market share.

    Eric Wesoff is the editorial director at Canary Media.

    Solar panels are a pain to recycle. These companies are trying to fix that.

    A new plant in France aims to extract silver from old solar panels to make recycling them worth the trouble.

    Millions of solar panels have been installed in the last two decades—and since they typically last between 25 and 30 years, many will soon be ready for retirement and probably headed to a landfill. But new efforts to recycle these panels could reduce both the amount of waste and the new material that needs to be mined.

    Only about 10% of panels in the US are recycled—it isn’t mandated by federal regulations, and recycling the devices is currently much more expensive than just discarding them. But the materials in solar panels coming offline each year could be worth an estimated 2 billion by 2050. New efforts, including one approach from a French startup called ROSI, are trying to recapture these valuable materials, especially silver and silicon, to make recycling the panels more financially viable.

    Related Story

    Plummeting sunny day solar are undermining the economic case to build more solar farms – and putting climate goals at risk.

    Expanding solar-power production is key to reducing emissions worldwide. Globally, solar panels produced 720 terawatt-hours of energy in 2019, accounting for around 3% of the world’s electricity generation. And it took about 46 million metric tons of solar panels to do it.

    About 8 million metric tons of decommissioned solar panels could accumulate globally by 2030. By 2050, that number could reach 80 million. Recycling these panels could provide a new source for materials that would otherwise need to be mined (potentially under unsafe or exploitative working conditions), making solar a more sustainable piece of the clean-energy puzzle.

    What’s in a solar panel?

    Solar panels are laid out like a sandwich with cells in the center. About 90% of commercial solar panels use silicon as the semiconductor, which converts light into electricity. Thin strips of metal, usually silver, crisscross the surface of silicon crystals in each cell and move electricity into the panel’s copper wiring.

    The solar cells are encased in a protective barrier, usually a transparent plastic called EVA. Another layer of glass goes on top, and a different kind of plastic, like PET, covers the back. The whole thing is surrounded by an aluminum frame.

    This layered construction protects cells from the elements while allowing sunlight through, but it can be difficult to deconstruct when the panels have reached the end of their life.

    A second life

    Some companies try to refurbish and reuse panels that have lost efficiency, or at least rescue some of their components. Reuse is the simplest and cheapest way to “recycle” panels—it requires the least processing and commands the highest price.

    A panel might cost around 55, while a used panel might be resold for around 22. Or the used panel’s components might be sold for a total of up to 18, according to Meng Tao, an engineering professor at Arizona State University and founder of a solar-panel recycling startup called TG Companies.

    Although some resellers offer used panels for sale to residential customers, they don’t offer much price savings. Panels only make up, at most, about half the cost of a residential solar array, with the other equipment and permits accounting for the rest. Given that used panels don’t generate as much electricity, the money saved by buying them might not be worth it.

    Used panels that can’t be resold are destined for either the landfill or some type of recycling. In the absence of federal mandates, Washington recently passed recycling requirements for manufacturers, and other states are now considering doing the same. The EU, meanwhile, requires manufacturers to collect and recycle used solar panels and fund research on end-of-life solutions for the technology they produce.

    About 8 million metric tons of decommissioned solar panels could accumulate by 2030.

    Some waste facilities can recycle solar panels using mechanical methods. Most pop off the aluminum frame and grind all the glass, silicon, and other metals into a mixture called glass cullet, which can be sold for building materials or other industrial applications.

    But cullet isn’t worth much—around 3 for a panel’s worth of the mixture. And it’s not clear if there will be buyers for all the cullet that would result from recycling many more solar panels, Tao says. Being able to extract pure, valuable materials might help make recycling more profitable.

    In 2018 the waste management company Veolia, based near Paris, opened what it says is the first recycling line developed specifically for recycling solar panels. Located in Rousset, France, the plant also uses a mechanical recycling process, although since it’s designed for solar panels, more components are recycled separately than at facilities using general e-waste recycling equipment. But some companies are betting that other methods, like thermal and chemical processes, will be even more efficient.

    Mining old panels

    ROSI Solar, a French startup founded in 2017, recently announced plans to build a new recycling plant in Grenoble, France. Yun Luo, ROSI’s CEO, says the company has developed a process to extract the silver, silicon, and other high-value materials from used panels. The plant should open before the end of 2022 with a contract from Soren, a French trade association.

    Soren is also working with a French logistics company called Envie 2E Aquitaine, which will try to find other uses for decommissioned solar panels. If the panels aren’t operational, the company will remove the aluminum frame and glass before passing them along to ROSI to recycle, Luo says.

    ROSI focuses on recovering silver and high-purity silicon, since these two materials make up over 60% of a panel’s cost. The company uses a proprietary chemical process on the remaining layers, focusing on removing the tiny silver threads that transmit electricity through a working solar panel.

    Luo declined to go into specifics but says the company can recover nearly all the silver in a solid form, so it’s easier to separate from the other metals, like lead and tin. Luo says that the company also recovers the silicon in a pure enough form to process and reuse in new panels or EV batteries.

    To be profitable, ROSI will need to recycle at least 2,000 to 3,000 tons of panels per year, Luo says. Soren expects to collect about 7,000 tons of panels in 2021, and that number will probably more than double by 2025.

    However, for the recycled materials can be fairly volatile. When Tao published a review paper on solar-panel recycling in June 2020, he calculated that the value of raw materials that could be extracted from a used panel would be around 10. By June 2021, he says, that number had nearly doubled, to 19, because of a jump in the price of solar-grade silicon. That increase made him rethink the recycling process he’s developing for his own startup.

    This price volatility means that the economics for recycling remain uncertain. And because silver is so expensive and limited, some researchers are working to reduce or even replace silver in new solar panels. While this could drive their price down further, it would also cut into the economic case for recycling, Tao says.

    What remains to be seen is the environmental impact of the recycling efforts themselves. Quantifying the effects they will have on pollution and emissions can help in deciding on the best approach to the solar-waste problem, says Garvin Heath, a senior energy sustainability analyst at the National Renewable Energy Laboratory. Heath is an expert in life-cycle analysis, which tallies up the environmental impacts of a technology from its production all the way to the end of its life.

    The way a technology affects the environment while it’s in use doesn’t always tell the full story. Manufacturing, transporting, and disposing of any technology generates emissions, and it’s important to take all of that into account, Heath says. Exactly how a panel is manufactured and recycled helps determine how helpful it really is in decreasing emissions.

    It’s a calculation we should consider for most of the technology we use every day, Heath adds. The total amount of global e-waste could hit 120 million metric tons annually by 2050, according to a UN report.

    “All technology has an end of life,” Heath says, “and you have to manage these technologies at that point.”

    This story previously stated that ROSI recovers PV-grade silicon. It has been corrected to note that additional processing would be required to purify the recovered silicon to PV-grade.

    Types of Solar Panels: Pros and Cons

    Emily Rhode is a science writer, communicator, and educator with over 20 years of experience working with students, scientists, and government experts to help make science more accessible and engaging. She holds a B.S. in Environmental Science and an M.Ed. in Secondary Science Education.

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    There are three main types of solar panels commercially available: monocrystalline solar panels, polycrystalline solar panels, and thin-film solar panels. There are also several other promising technologies currently in development, including bifacial panels, organic solar cells, concentrator photovoltaics, and even nano-scale innovations like quantum dots.

    Each of the different types of solar panels has a unique set of advantages and disadvantages that consumers should consider when choosing a solar panel system.

    Monocrystalline solar cells are slower and more expensive to produce than other types of solar cells due to the precise way the silicon ingots must be made. In order to grow a uniform crystal, the temperature of the materials must be kept very high. As a result, a large amount of energy must be used because of the loss of heat from the silicon seed that occurs throughout the manufacturing process. Up to 50% of the material can be wasted during the cutting process, resulting in higher production costs for the manufacturer.

    But these types of solar cells maintain their popularity for a number of reasons. First, they have a higher efficiency than any other type of solar cell because they are made of a single crystal, which allows electrons to flow more easily through the cell. Because they are so efficient, they can be smaller than other solar panel systems and still generate the same amount of electricity. They also have the longest life span of any type of solar panel on the market today.

    One of the biggest downsides to monocrystalline solar panels is the cost (due to the production process). In addition, they are not as efficient as other types of solar panels in situations where the light does not hit them directly. And if they get covered in dirt, snow, or leaves, or if they are operating in very high temperatures, their efficiency declines even more. While monocrystalline solar panels remain popular, the low cost and rising efficiency of other types of panels are becoming increasingly appealing to consumers.

    Polycrystalline Solar Panels

    As the name implies, polycrystalline solar panels are made of cells formed from multiple, non-aligned silicon crystals. These first-generation solar cells are produced by melting solar grade silicon and casting it into a mold and allowing it to solidify. The molded silicon is then sliced into wafers to be used in a solar panel.

    Polycrystalline solar cells are less expensive to produce than monocrystalline cells because they do not require the time and energy needed to create and cut a single crystal. And while the boundaries created by the grains of the silicon crystals result in barriers for efficient electron flow, they are actually more efficient in low-light conditions than monocrystalline cells and can maintain output when not directly angled at the sun. They end up having about the same overall energy output because of this ability to maintain electricity production in adverse conditions.

    The cells of a polycrystalline solar panel are larger than their monocrystalline counterparts, so the panels may take up more space to produce the same amount of electricity. They are also not as durable or long-lasting as other types of panels, although the differences in longevity are small.

    Thin-Film Solar Panels

    The high cost of producing solar-grade silicon led to the creation of several types of second- and third-generation solar cells known as thin-film semiconductors. Thin-film solar cells need a lower volume of materials, often using a layer of silicon as little as one micron thick, which is about 1/300th of the width of mono- and polycrystalline solar cells. The silicon is also of lower quality than the kind used in monocrystalline wafers.

    Many solar cells are made from non-crystalline amorphous silicon. Because amorphous silicon does not have the semiconductive properties of crystalline silicon, it must be combined with hydrogen in order to conduct electricity. Amorphous silicon solar cells are the most common type of thin-film cell, and they are often found in electronics like calculators and watches.

    Other commercially viable thin-film semiconductor materials include cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and gallium arsenide (GaAs). A layer of semiconductor material is deposited on an inexpensive substrate like glass, metal, or plastic, making it cheaper and more adaptable than other solar cells. The absorption rates of the semiconductor materials are high, which is one of the reasons they use less material than other cells.

    Production of thin-film cells is much simpler and faster than first-generation solar cells, and there are a variety of techniques that can be used to make them, depending on the capabilities of the manufacturer. Thin-film solar cells like CIGS can be deposited on plastic, which significantly reduces its weight and increases its flexibility. CdTe holds the distinction of being the only thin film that has lower costs, higher payback time, lower carbon footprint, and lower water use over its lifetime than all other solar technologies.

    However, the downsides of thin-film solar cells in their current form are numerous. The cadmium in CdTe cells is highly toxic if inhaled or ingested, and can leach into the ground or water supply if not properly handled during disposal. This could be avoided if the panels are recycled, but the technology is currently not as widely available as it needs to be. The use of rare metals like those found in CIGS, CdTe, and GaAs can also be an expensive and potentially limiting factor in producing large amounts of thin-film solar cells.

    Other Types

    The variety of solar panels is much greater than what is currently on the commercial market. Many newer types of solar technology are in development, and older types are being studied for possible increases in efficiency and decreases in cost. Several of these emerging technologies are in the pilot phase of testing, while others remain proven only in laboratory settings. Here are some of the other types of solar panels that have been developed.

    Bifacial Solar Panels

    Traditional solar panels only have solar cells on one side of the panel. Bifacial solar panels have solar cells built on both sides in order to allow them to collect not only incoming sunlight, but also albedo, or reflected light off the ground beneath them. They also move with the sun in order to maximize the amount of time that sunlight can be collected on either side of the panel. A study from the National Renewable Energy Laboratory showed a 9% increase in efficiency over single-sided panels.

    Concentrator Photovoltaic Technology

    Concentrator photovoltaic technology (CPV) uses optical equipment and techniques such as curved mirrors to concentrate solar energy in a cost-efficient way. Because these panels concentrate sunlight, they do not need as many solar cells to produce an equal amount of electricity. This means that these solar panels can use higher quality solar cells at a lower overall cost.

    Organic Photovoltaics

    Organic photovoltaic cells use small organic molecules or layers of organic polymers to conduct electricity. These cells are lightweight, flexible, and have a lower overall cost and environmental impact than many other types of solar cells.

    Perovskite Cells

    The Perovskite crystalline structure of the light-collecting material gives these cells their name. They are low cost, easy to manufacture, and have a high absorbance. They are currently too unstable for large-scale use.

    Dye-Sensitized Solar Cells (DSSC)

    These five-layered thin-film cells use a special sensitizing dye to help the flow of electrons which creates the current to produce electricity. DSSC have the advantage of working in low light conditions and increasing efficiency as temperatures rise, but some of the chemicals they contain will freeze at low temperatures, which makes the unit inoperable in such situations.

    Quantum Dots

    This technology has only been tested in laboratories, but it has shown several positive attributes. Quantum dot cells are made from different metals and work on the nano-scale, so their power production-to-weight ratio is very good. Unfortunately, they can also be highly toxic to people and the environment if not handled and disposed of properly.

    Almost all solar panels sold commercially are monocrystalline, common because they’re so compact, efficient, and long-lasting. Monocrystalline solar panels are also proven to be more durable under high temperatures.

    Monocrystalline solar panels are the most efficient, with ratings ranging from 17% to 25%. In general, the more aligned the silicon molecules of a solar panel are, the better the panel will be at converting solar energy. The monocrystalline variety has the most aligned molecules because it’s cut from a single source of silicon.

    Thin-film solar panels tend to be the cheapest of the three commercially available options. This is because they’re easier to manufacture and require less materials. However, they also tend to be the least efficient.

    Some may choose to buy polycrystalline solar panels because they’re cheaper than monocrystalline panels and less wasteful. They’re less efficient and bigger than their more common counterparts, but you might get more bang for your buck if you have abundant space and access to sunshine.

    Thin-film solar panels are lightweight and flexible, so they can better adapt to unconventional building situations. They’re also much cheaper than other types of solar panels and less wasteful because they use less silicon.

    • Luceño-Sánchez, José Antonio, et al. Materials for Photovoltaics: State of Art and Recent Developments. International Journal of Molecular Sciences, vol. 20, no. 4, 2019, pp. 976., doi:10.3390/ijms20040976
    • Solar Photovoltaic Cell Basics. U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy.
    • Qazi, Salahuddin. Standalone Photovoltaic (PV) Systems for Disaster Relief and Remote Areas. Elsevier, 2017., doi:10.1016/C2014-0-03107-3
    • Bayod-Rújula, Angel Antonio. Chapter 8—Solar Photovoltaics (PV). Solar Hydrogen Production: Processes, Systems and Technologies, 2019, pp. 237-295., doi:10.1016/B978-0-12-814853-2.00008-4
    • Taraba, Michal. Properties Measurement of the Thin Film Solar Panels Under Adverse Weather Conditions. Transportation Research Procedia, vol. 40, 2019, pp. 535-540., doi:10.1016/j.trpro.2019.07.077
    • Bagher, Askari Muhammed, et al. Types of Solar Cells and Applications. American Journal of Optics and Photonics, vol. 3, no. 5, 2015, pp. 94-113., doi:10.11648/j.ajop.20150305.17
    • Project Profile: Performance Models and Standards for Bifacial PV Module Technologies. U.S. Department of Energy.
    • Bifacial Solar Advances With the Times—and the Sun. National Renewable Energy Laboratory.
    • Current Status of Concentrator Photovoltaic (CPV) Technology. National Renewable Energy Laboratory.

    What you need to know about polysilicon and its role in solar modules

    Polysilicon, a high-purity form of silicon, is a key raw material in the solar photovoltaic (PV) supply chain. To produce solar modules, polysilicon is melted at high temperatures to form ingots, which are then sliced into wafers and processed into solar cells and solar modules.

    How polysilicon is manufactured

    Three are three main technologies to produce polysilicon.

    The ‘modified Siemens process’ is currently the dominant technology in China. Trichlorosilane (TCS) is produced using two readily available metallurgical-grade silicon (of 95-99% purity) and liquid chlorine.

    After being purified through distillation, the TCS is vaporised and mixed with hydrogen gas. In a deposition reactor, silicon slim rods are heated up to 1 100C and the passing of the gas mixture results in high-purity silicon being deposited on the surface of the rods. This process continues until a certain diameter (typically 150-200mm) is achieved.

    Fluidised bed reactor process (FBR) and the upgraded metallurgical-grade silicon process (UMG) are the other two technologies.

    • FBR uses significantly less electricity with a higher conversion rate by using silicon seed particles instead of silicon rods. It is a less mature technology and only a few polysilicon producers currently use it in some of their plants. [1]
    • UMG uses physical methods to extract impurities directly from the silicon metal instead of chemical processes, which reduces energy usage. [2] However, silicon produced using UMG does not have as high purity as the other two methods do and therefore is not widely used.

    Recent market trends in the polysilicon industry

    The polysilicon industry has increasingly consolidated, with the top-five companies accounting for 73% of global production in 2020 compared to 60% in 2017, according to BNEF. This is mainly due to a number of companies shutting down capacities in recent years after a period of overcapacity. These companies could not compete with low-cost producers that have greater scale and efficiencies in a low-price environment.

    In addition, China imposed tariffs on polysilicon imports. This benefited local producers who already had a cost advantage compared to international peers. China accounted for 77% of global polysilicon production in 2020. Manufacturing takes place mostly in Xinjiang, Yunnan or Sichuan where electricity is cheaper lower and the raw material is close by.

    After supply chain disruptions led to higher polysilicon in Q3 2020, have risen significantly further since the start of 2021 due to market tightness.

    In anticipation of strong demand – solar installation is forecast to increase by 15% a year for the next three years (according to BNEF) – downstream wafer companies boosted capacity by 45% in 2020.

    This growing demand from wafer companies that use polysilicon to make wafers has created a supply-demand imbalance. One producer expects supply to remain tight until the middle of 2022, when new capacity is expected to come on stream.

    What about labour practices in China?

    In June 2021, US Customs and Border Protection issued a ‘withhold release order’ targeting a major supplier of metallurgical silicon powder over allegations that it used forced labour. [3] Enforcement will likely be through downstream companies which this supplier sells to. This could detail cargoes into the US until the supply chain source is clear.

    However, since the US accounts for less than 2% of mainland China’s solar PV exports (average in the last three years), we believe local companies can leverage manufacturing plants outside of Xinjiang, where this major supplier is located, to serve the US market.

    Separately, the US blacklisted other Chinese companies that it said were involved in human rights violations in Xinjiang. At least some of the companies listed by the Commerce Department are major manufacturers of monocrystalline silicon and polysilicon that are used in solar panel production.

    A potential market impact could be a further tightening of the polysilicon market, especially if a premium emerges for polysilicon sourced outside of Xinjiang, which is a low-cost producing region due to its low electricity costs. This could cause polysilicon to rise and hold at higher levels. Costs for module manufacturers could increase as they have to demonstrate their supply chain audit trail.

    [3] From the CBP statement: “This Withhold Release Order demonstrates we continue to protect human rights and international labor standards and promote a more fair and competitive global marketplace by fulfilling the Biden-Harris Administration’s commitment to ending forced labor.”

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