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Sorry, Coal: 66% Conversion Efficiency Eyeballed For Next-Gen “Hot Carrler”…

Sorry, Coal: 66% Conversion Efficiency Eyeballed For Next-Gen “Hot Carrler”…

    Sorry, Coal: 66% Conversion Efficiency Eyeballed For Next-Gen “Hot Carrler” Perovskite Solar Cells

    The US is going all-in on a plan to dominate the global PV market with next-gen perovskite solar cells that can beat fossil fuels to a pulp.

    Election business is dominating the headlines over here in the US, but somehow the Department of Energy snuck in two pieces of news that squeeze more breath out of the nation’s beleaguered coal industry. The agency issued a new report that touts the benefits of oil and gas while leaving coal outside in the rain, and new research from an Energy Department laboratory indicates that next-generation perovskite solar cells could be far less expensive, and far more efficient, than any other PV currently available today.

    The US is going all-in on next-gen perovskite solar cells that will beat fossil fuels to a pulp.

    Everybody Hates Coal

    The timing of that new oil and gas report is especially interesting, considering that The New York Times also piled onto coal earlier this month with a new long-form article describing just how far the coal industry has declined during the Trump administration, despite all those promises about saving coal jobs.

    Wouldn’t this be a good time to rush to the defense of coal jobs instead of cheerleading for oil and gas? Just asking! After all, low cost natural gas has been the main force driving coal out of the power generation market.

    Nevertheless, the Energy Department seems content to let gas push coal out of the picture.

    “Not only is natural gas the largest contributor to the Nation’s electric power generation, but oil and natural gas combined are revitalizing the U.S. petrochemical manufacturing industry, supplying high-tech materials, increasing commerce from exporting liquefied natural gas, supporting renewable energy, and creating well-paying jobs across the country,” DOE explains.

    Perovskite Solar Cells Aim Dagger At Heart Of Natural Gas

    The Energy Department’s rosy outlook for oil and gas brushes off a rapidly accelerating trend, in which low cost renewable energy gives both coal and natural gas a run for the money in the power generation sector.

    That’s where the new next-generation solar cells come in.

    To be clear, silicon is still the gold standard for solar cell efficiency, and the cost of silicon solar cell costs has been spiraling downward. However, the cost of solar power is still a turnoff for many consumers. If a less pricey photovoltaic alternative could materialize, the pace of the renewable energy transition would pick up considerably.

    With that in mind, the Energy Department is betting the ranch on a class of synthetic crystalline materials called perovskites. To support its case, the agency regularly cites the trajectory of perovskite solar cell efficiency improvements in the past few years. Serious research into perovskite solar cells began in 2009 at just 3% conversion efficiency, and now the latest perovskite PV iteration clocks in at 25%.

    Eleven years is just the wink of an eye in the field of solar cell research. For context, consider that the first commercial silicon PV device was developed by Bell Labs with a conversion efficiency of 6% all the way back in 1954. Now here it is more than 60 years later, and commercial silicon has barely scraped into the 25% range.

    High-Performance Perovskite PV On The Way

    For those of you new to the topic, solar conversion efficiency is a way of measuring how good a solar cell is at converting light into electricity. The 100% mark is pretty much out of the question, but researchers have calculated that silicon PV maxes out at around 30%.

    Conversion efficiency can bump up if other materials are added to the PV mix, but all else being equal, that means the cost bumps up, too.

    Perovskites can shave some of the cost burden off the equation, and with that in mind let’s take a look at the latest news from the Energy Department’s Oak Ridge National Laboratory in Tennessee.

    In a team effort with the University of Tennessee, Knoxville, ORNL spearheaded a new perovskite PV study that shines a light, so to speak, on a new pathway for improving perovskite solar cell efficiency.

    “The discovery could improve novel hot-carrier solar cells, which convert sunlight to electricity more efficiently than conventional solar cells by harnessing photogenerated charge carriers before they lose energy to heat,” ORNL enthused in a press release last week.

    The idea is to prevent the solar cell from wasting energy in the form of heat, as ORNL explains:

    “When sunlight strikes a solar cell, photons create charge carriers — electrons and holes — in an absorber material. Hot-carrier solar cells quickly convert the energy of the charge carriers to electricity before it is lost as waste heat. Preventing heat loss is a grand challenge for these solar cells, which have the potential to be twice as efficient as conventional solar cells.”

    “The conversion efficiency of conventional perovskite solar cells has improved from 3% in 2009 to more than 25% in 2020. A well-designed hot-carrier device could achieve a theoretical conversion efficiency approaching 66%,” the lab adds.

    The basic idea is to reduce swaying in the solar material by removing hydrogen. That enables the calmed-down material to interact with vibrations that would otherwise remove heat.

    For all the juicy details, check out the team’s study under the somewhat intimidating title, “Giant isotope effect on phonon dispersion and thermal conductivity in methylammonium lead iodide,” in the journal Science Advances.

    Everybody Loves Perovskite Solar Cells

    The Energy Department brought in the heavy artillery to support the ORNL effort. The agency’s Office of Science chipped in for the research along with the Vehicle Technology Office from the Office of Energy Efficiency and Renewable Energy, and so did the US Department of Homeland Security.

    Wait — DHS? If you have any ideas on that angle, drop a note in the comment thread.

    The Office of Science is billed as the “single largest supporter of basic research in the physical sciences in the United States,” but that’s just the tip of the iceberg of forces arrayed in support of perovskite solar cells.

    Last spring the Energy Department’s National Renewable Energy Laboratory launched a new consortium aimed at staking out the pole position for the US in the global PV market.

    The executive board of the so-named US Manufacturing of Advanced Perovskites Consortium (US-MAP) is spearheaded by NREL and joined by the Washington Clean Energy Testbeds at the University of Washington, the University of North Carolina at Chapel Hill, and the University of Toledo.

    On the industry side, NREL has recruited an advisory board consisting of the US companies BlueDot Photonics, Energy Materials Corporation, First Solar, Hunt Perovskites Technologies, Swift Solar, and Tandem PV.

    The University of Colorado at Boulder and the SLAC National Accelerator Laboratory are also on board, and US-MAP is probably eyeballing the potential to expand its network as we speak.

    On Beyond Solar

    Aside from solar energy applications, NREL points out that “perovskites have shown tremendous promise in a range of other technologies, including solid-state lighting, advanced radiation detection, dynamic sensing and actuation, photo-catalysis, and quantum information science.”

    Tooting its own horn, NREL credits the Energy Department’s Solar Energy Technologies Office and Office of Science with supporting early-stage research that has stimulated a rich trove of perovskite expertise in the domestic sphere.

    The new consortium will coordinate efforts to ensure that perovskite solar materials make it out of the lab and onto the shelves of your local hardware store.

    “While perovskite cells have shown promise in the lab, more work remains to be done to ensure that the technology is ready for commercial success. Manufacturing, durability, and sustainability remain challenges and will be the consortium’s research FOCUS,” NREL explains. “Members of US-MAP will share research and development, validation, and pilot manufacturing, which will reduce development costs and technology risks for potential investors.”

    That sound you hear is the collapse of the US coal industry, to be followed shortly by oil and gas.

    Condolences to the family and friends of ORNL engineer William Collier, who passed away last week after becoming infected with the COVID-19 virus.

    Image: “Substituting deuterium for hydrogen makes methylammonium heavier and slows its swaying so it can interact with vibrations that remove heat, keeping charge carriers hot longer” (credit: Jill Hemman/ORNL, U.S. Dept. of Energy).

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    The Best Ways to Maximize Solar Panel Efficiency

    Energy efficiency is an important factor to consider as you shop for home solar panels, but what does energy efficiency mean? We’re here to help you make sense of solar panel efficiency, and we’ll help you maximize it so you can get the most out of your home solar system.

    Want an industry-leading solar system for as little as 0 down? Schedule a solar consultation with one of our expert Solar Advisors today.

    How Efficient Are Solar Panels?

    To determine solar panel efficiency, sometimes referred to as photovoltaic conversion efficiency, we measure how much energy from sunlight is transformed into electricity. 1 The average commercial solar panel converts 17-20% of sunlight into electricity. 2 While 20% might not sound like a lot, it’s enough to keep the average American home powered throughout the day. Even the best semiconductors only capture a fraction of the light that strikes them. 3 Much of the light that strikes solar panels is reflected back, passes through the panel, or is converted into heat instead of electricity. 3 That’s why the residential solar panels you often see appear dark blue or black. 4 These “anti-reflection” coatings ensure the solar panels absorb as much sunlight as possible to maximize efficiency. 4

    Do Solar Panels Degrade over Time?

    As with most technologies, solar panels will naturally produce less energy over time. This reduced power output is called the degradation rate. The median solar panel degradation rate is about 0.5%, which simply means that a solar panel’s energy production will decrease at a rate of 0.5% per year. 5 After 20 years, your panels should still be working at about 90% of its original output.

    While solar systems typically last upwards of 20 years, repairing and replacing a solar energy system can come at a high cost. 6 When you lease a solar system with Sunrun, all you have to do is pay for the power—we’ll take care of the rest. Our solar lease includes free system monitoring, maintenance, and repairs so you can enjoy 25 years of worry-free, clean energy.

    How Does Weather Affect Solar Panel Efficiency?

    Even in below-freezing weather, solar panels turn sunlight into electricity. That’s because solar panels absorb energy from our sun’s abundant light, and not from the sun’s heat. In fact, cold climates are actually optimal for solar panel efficiency. 7 As long as sunlight is hitting a solar panel, it will generate electricity. Less output during the winter months will primarily be due to shorter daylight hours, or possibly heavy snow.

    This doesn’t mean that solar panel output will decrease in warmer weather; any diminished efficiency is balanced out thanks to more daylight hours during the spring and summer months. 7

    Do Solar Panels Work in Rain and Snow?

    If your winters look cloudy, rainy, snowy, or all of the above, not to worry. Solar panels can still generate electricity under these conditions, too. While solar panels are most productive in direct sunlight, they can still use diffuse or indirect sunlight (radiation) to generate energy. 8

    Even though energy production decreases with increasingly dense Cloud cover, panels continue working to a greater capacity than one may expect. Rain also helps wash away dust on panels to keep them operating efficiently. 9

    During times of heavy snow accumulation, solar panels’ dark, reflective glass accelerates snow melt so that it slides off before it can hamper performance. Rooftop solar panels are also typically tilted up at 30 to 45 degrees, which keeps snow from accumulating, but only to a point. 11 In comparison, a light dusting of snow is likely to blow off or disappear rapidly.

    In fact, on cold, clear days, snow from the ground can reflect extra sunlight onto your solar panels like a mirror. This “albedo effect” enables panels to produce even more electricity in the cold. 10

    If your panels require more than a routine hosing down or require you to get on the roof, we highly urge you to contact a trusted solar provider to receive professional assistance.

    Three Tips on Maintaining Solar Panel Efficiency

    While solar panels generally require little maintenance, it’s still important to inspect your solar panels from time to time and monitor their performance. Here are a few tips to ensure your solar installation is working at its full capacity: 12

      Keep your panels clear of debris and other damaging materials. While rain is generally sufficient to keep your panels clean, you may want to consider a professional cleaning if you ever notice your panels aren’t working at their full capacity.

    Energy Efficiency vs. Cost Efficiency

    While solar panel efficiency is important to consider, cost efficiency will likely be the most relevant factor in your search for a home solar panel system. Sunrun ensures you have a cost-efficient system in three ways:

      We only recommend solar if it has the potential to save you money. Sunrun will help you determine whether a solar panel system has the potential to cut the cost of your current electricity rates. Our easy-to-use Product Selector will ask you for your average monthly electricity bill so our Solar Advisors can determine if solar makes financial sense for you.

    Renewable Energy and Efficient Solar Panels for Your Energy Needs

    A reputable residential solar company will guarantee reliable solar panel production and dependable customer service for decades to come. With over 20 years of experience, Sunrun is committed to creating a clean energy future for all.

    See why over 600,000 Americans across the country have partnered with Sunrun and get a solar consultation today. You can also use our easy Product Selector to get a solar system that’s custom-fit to meet your needs.

    • 1. Photovoltaic Energy Factsheet
    • 2. Solar Energy Optics: expanding efficiency
    • 3. Solar panels are more efficient than you’ve heard. This material could make them even better.
    • 4. Solar Performance and Efficiency
    • 5. Lifetime of PV Panels
    • 6. How Much Do Solar Panels Cost?
    • 7. How Does Temperature Affect Solar Panels?
    • 8. Direct, Diffuse and Reflected Radiation
    • 9. Just a spoonful of solar panel cleaning, helps the revenue go up – the revenue go up!
    • 10. Solar Panels Work Great In Snowy Regions, Research Shows
    • 11. Let it Snow: How Solar Panels Can Thrive in Winter Weather
    • 12. How Much Does It Cost To Clean And Maintain Solar Panels?
    • 13. Short-term Energy Outlook

    Which are the factors that affect solar panels’ efficiency?

    Solar power systems are considered a key tool in the energy supply for the present and future generations. Several factors have promoted the development of photovoltaics such as environmental concerns, incentives and tax deductions, a more performing and less expensive technology and the need to replace carbon fossil energy systems with renewables to ensure compliance with the objectives set by the Paris COP y limit global warming to 1.5 ° C.

    A solar cell or photovoltaic cell is a device that converts the sunlight into usable energy. The amount of sunlight that can be converted into electricity is referred to as solar cell efficiency. There are some factors that should be taken into consideration to guarantee the optimal efficiency of the solar panels.


    The temperature influences the efficiency of the photovoltaic cell due to the intrinsic characteristic of the semiconductor material. The efficiency of the solar panels increases when the temperature drops and decreases in high temperatures, as the voltage between the cells drops.

    Energy Conversion Efficiency

    The solar module has a different spectral response depending on the kind of the module. Therefore, the change of the spectral irradiance influences the solar power generation. The energy conversion efficiency is increased by reducing the reflection of the incident light.

    Solar Shadings

    Solar PV panels are very sensitive to solar shadings. Total or partial shading conditions have a significant impact rate on the capability of delivering energy and may result in lower output and power losses. Cells in a solar panel are usually connected in series to get a higher voltage and therefore an appropriate production of electricity.

    But when shading occurs, this structure presents some limitations. In fact, when a single solar cell is shaded, the current of all the units in the string is determined by the unit that produces the least current. When a cell is shaded, the whole series is virtually shaded too. To prevent the loss of energy, the installation usually includes bypass diodes.

    Bypass diodes are wired in parallel to the solar cells. When a solar cell is shaded, the bypass diode provides a current path that allows the string of connected solar cells to generate energy at a reduced voltage. Read more.

    The Orientation, Inclination, Latitude of the place and Climatic conditions

    The installation of the photovoltaic modules must take into account some factors to take full advantage of solar radiation: the orientation, the inclination, the latitude of the place, the climatic conditions. The correct consideration of these variants will help ensure that they produce maximum energy by being exposed to the greatest intensity of solar radiation for the longest period of time. Learn more.

    Operation and Monitoring

    OM services help with the management of the implementation of certain processes to avoid or mitigate potential hazards and to guarantee the optimal return on investment. Operations mainly consist of the remote monitoring and control of the PV power plant conditions and performance. Monitoring software provides access to all data collected, which can be used for different purposes: defect detection, performance analysis, improvement, predictive maintenance, and security. A good monitoring system will provide information on the production, alarms, and analytical data, in a timely, efficient, and precise manner to detect any anomaly of the PV plant. Continue reading.


    Solar panels are very durable, main warranties last for 15-25 years. However, cleaning solar panels is important to maximize the amount of light available to turn into electrical power. Making frequent physical inspections can help solar panels absorbing light effectively.

    archelios™ Suite

    archelios™ Suite is a comprehensive software solution that offers a unique approach. Thanks to its advanced computational technology, archelios™ Suite adds value to the life-cycle of any PV project: feasibility and profitability study, simulation, calculation of producible energy, complete electrical sizing, operation, and monitoring.

    The software is an efficient tool for any type of PV project.


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    Why Are Solar Panels Inefficient?

    Solar energy development continues as the market evolves into more profitable photovoltaic system solutions in the long and medium term. The trend shows an exponential growth that started with around 6 GW of installed capacity in 2006 and evolved to almost 480.3 GW at the end of 2018 worldwide [1]. Such accelerated growth could not even be foreseen back in the old days by the best specialists.

    Ten years ago, solar installation costs were high above the clouds, making it very hard for homeowners to own a solar photovoltaic system. Policy and incentive schemes were also not clearly established or profitable, representing high investment risks that worked against the best environmental desires.

    Among other reasons, one of the main limitations for entering the residential market was low efficiency of solar systems. Efficiency of solar panels represents how much of sunlight that hits a solar cell gets transformed into electricity. Some of the first solar panels had efficiencies between 8 to 10 percent. Other traditional sources of energy had efficiency of 40 to 55 percent with the combined cycle generators [2]. The competition was just unbalanced.

    Nowadays, solar installation costs are competitive with traditional energy sources. Policy and incentive schemes are solid and profitable for homeowners in most high-income countries. Solar cell efficiency has increased due to advancements in photovoltaic technology to the range between 15 and 22 percent. This number may not seem so competitive to many who have doubts about fully transitioning to solar energy.

    Let’s have a look at reasons why are photovoltaic solar panels still inefficient.

    Understanding why is solar cell efficiency low?

    To understand efficiency of a solar panel, you must first understand its source of energy – the Sun.

    Sun emits energy in a form of light which is composed of photons. Each photon has different energy and wavelength range (from ultraviolet to infrared). Photons are used by photovoltaic cells in solar panels to convert sunlight into electricity.

    The cells are made of a semiconductor material (p-n junction), which facilitates generation of electric current when photons get absorbed. But a bigger part of sunlight that hits the cells isn’t converted into electricity. Why is that?

    The problem with solar cell efficiency lies in the physical conversion of sunlight.

    In 1961, William Shockley and Hans Queisser defined the fundamental principle of the solar photovoltaic industry. Their physical theory proved that there is a maximum possible efficiency of 33.7 percent which a standard photovoltaic cell (based on a p-n junction) can achieve to generate electricity from a light source [2]. In other words, if the sun’s direct light is received by a surface per area of 1,000 watts per one square meter, then the maximum power output that a solar panel could produce is 337 watts per square meter.

    This physical limitation is known as the Shockley-Queisser limit and is caused by the physical process of photon absorption by the semiconductor material that knocks loose electrons from their atoms and then passes them to the conduction Band within the solar cell [2]. Some photons that hit a solar cell are reflected away from the cell’s surface. Out of those photons that are absorbed, some have their energy turned into heat in a process of internal recombination instead of producing electric current.

    These efficiency losses are inevitable. There is no manufacturing process or technology development that can change this limit — at least not with silicon p-n junction solar cells.

    The Shockley-Queisser limitation defines the theoretical level of maximum possible efficiency of a solar cell, but in the daily life, efficiency of solar energy conversion is affected also by other factors (discussed below).

    Standard Test Conditions for verifying solar panel efficiency

    To establish the efficiency value, manufacturers submit solar panels to several controlled factors that can exist in real world applications. They do this testing to make sure that the design endures these conditions, while at the same time, they verify estimated efficiency (as it is visible in the electrical characteristics of the datasheet).

    It is important to know that many manufacturers establish solar cell efficiency based on Standard Test Conditions (STC).

    STC are set on maximum possible solar irradiance (1kW per m2), at temperature of 25 degrees Celsius or 77 degrees Fahrenheit, and an air mass of 1.5 (related to the thickness of the atmosphere) [4].

    It is rare to have the same conditions in the real life. Temperature and irradiance particularly can be very different from those values.

    Nominal Operating Cell Temperature to simulate real life conditions

    That is why some manufacturers add the Nominal Operating Cell Temperature (NOCT) among their technical references.

    The NOCT is a parameter closer to real life situations and is defined as the temperature reached by an open circuit cell in a module under the following conditions [4] :

    • Mounting System: Open back side (to consider air circulation behind the solar panel for refreshing purposes)

    Now that you know how efficiency is specified by manufacturers, we can proceed with the factors that are taken into account for the design of solar panels to maintain acceptable efficiency values.

    What factors affect solar panel efficiency in daily life?

    #1 Hail, snow, ice and dust

    Hail could in extreme scenarios damage the surface of solar panels and reduce their efficiency by decreasing the amount of sunlight they absorb. However, you should also know that solar panels are durable and meant to withstand hail at a speed of 20 to 30 meter per second (45 to 67 miles per hour). For a better idea, it is estimated that a hailstone with diameter of 1 centimeter or around 0.4 inches falls at a rate of 9 m/s (20 mph). Solar panels should resist even two to three times that. You should be safe during that early spring overcast.

    Thick layers of snow can directly block sunlight accessing solar panels and cut efficiency down to zero [6]. It is important to know that most solar panels can still work with a layer of three to four centimeters of snow (approx. 1.5 inches). If the layer is thicker than that, you should remove the snow.

    Just like snow, dust and dirt can influence efficiency values on the same principle. When the layer is too thick to obstruct the light from reaching the solar panel surface, it will affect negatively how much energy the panel produces.

    Ice is another element that affects solar panels’ efficiency between 25 to 100 percent, depending on the thickness of the ice layer. To prevent this problem, a silicon coating is applied to a solar panel surface, but even despite that it’s advisable to keep ice off your panels during the winter season [6].

    #2 Insulation resistance

    Besides the safety concerns, faulty insulation decreases solar module efficiency because current leakages can occur along the edges of solar panels. Be especially careful in areas with high humidity. Humidity speeds up corrosion of materials. Advanced level of corrosion eventually leads to insulation issues and decreases overall solar panel efficiency faster than expected.

    Problems with insulation may occur in poor quality solar panels made of cheaper materials, or when solar cells are too close to the frame.

    Insulation resistance is especially important for utility-scale projects as higher voltage systems require better insulation properties, which are linked directly to selected materials.

    #3 Temperature of solar panels

    Solar cells are sensitive to warmer temperature. Higher temperature outside means that the semiconductor material of solar panels gets hot quickly and slightly changes properties, which is linked to electrical losses and voltage drops.

    It is estimated that an increase per one unit of temperature above the standard test temperature of around 25 degrees Celsius or 77 degrees Fahrenheit decreases the panel’s energy output by 0.25 to 0.5 percent (depending on the module type) [7].

    If you think about it: temperature increase of around 60 degrees Celsius (140°F) could reduce the power outcome of your solar panel by 17.5 percent. So, the effect of temperature can be significant in countries with hot climate. Long term exposure to hot temperature may also shorten lifetime of the material.

    On the other hand, you do not need to worry about colder temperatures, as long as the sun shines and solar panels receive unobstructed sunlight during the day, they will be producing at around their estimated efficiency. The only common problem in winter in regard to solar energy production is that the number of sunny days is much lower when compared to summer, and your system generates less on a monthly basis.

    #4 Selection of the solar panel type

    Not all solar panels are the same, neither is their price, which very often depicts not only the quality of materials and durability of the product, but also solar cell efficiency in converting sunlight in electricity. In daily life this usually means that you need less solar panels with higher efficiency rating to produce the same amount of power from their surface than you would need if you selected lower efficiency panels.

    The main difference in efficiency values of different panel types lies in the nature of how they have been manufactured and what semiconductor material they are made of. The most common semiconductor used in solar cells is silicon. In case of silicon, efficiency still differs based on the type of cells. The best quality are solar cells made of monocrystalline silicon, other common forms are polycrystalline or amorphous cells.

    Monocrystalline panels composed of a single crystal due to their structure allow for the best efficiency between 15 to 22 percent. Polycrystalline panels reach between 13 to 16 percent of efficiency and thin film panels made from amorphous cells have reached to 20 percent.

    What also matters is how much light is reflected from the solar cell surface. The goal is to minimize light reflection and that is why many solar panels have special anti-reflection coating and are dark in color – black in case of monocrystalline and thin film panels and dark blue polycrystalline.

    #5 Design configuration of solar panels

    Among other factors associated with the operation of solar panels, the selection of the orientation towards the sun and the presence of a solar tracking system has a great importance on overall efficiency of your solar system.

    Your solar panels will have the best power output when the solar panel surface is perpendicular to solar rays. However, as the sun moves across the sky, their angle changes as well. What you can do to ensure direct irradiance is to install a tracking system. Its downside are higher installation costs.

    Solar panel efficiency also changes over the time. Every year that passes after your solar system installation, the efficiency value drops by about 0.5 percent per year. Nevertheless, solar panel manufacturers have to guarantee that the performance of your solar system will not drop below 80 percent when in warranty, which usually lasts 25 years.

    Finally, shading is also an important part of the design of any solar system. If your system is shaded for the sunniest time of the day, solar panel output will be affected severely.

    New solar technologies to improve efficiency

    Despite low efficiency rates among current solar panels, there are several innovative proposals and technologies that aim to change how efficient can solar panels get in the close future.

    #1 Reducing the shading effects of wires

    Among available proposals is the reduction of the shading effect on solar cells caused by bus bars.

    Bus bars are located vertically and horizontally across a solar panel. They can be easily identified by any person as silver wires forming a grid inside a solar panel. They transport electricity generated by solar cells.

    These wires, even as tiny as they are, reflect the incoming light in sections where they pass by. In the end, this translates into less irradiance received by solar panels, and therefore, generation of less power.

    The idea is to reduce the thickness of these wires, or in the best case to eliminate their interference with the sunlight by placing them on the back of a panel. This would achieve a uniform smooth colored panel [8].

    #2 Innovative gallium arsenide triple-junction structure

    Another interesting feature that has been set in motion is the development of the new generation of powerful solar cells from gallium arsenide.

    Gallium arsenide cells have a triple-junction structure (different from silicon p-n junction) that can be chemically modified to acquire more light radiation than ordinary cells.

    Among remarkable advantages of these cells is:

    • Excellent ultraviolet, radiation and moisture resistance;
    • Great performance in the presence of low light;
    • Flexibility and low weight;
    • Efficiency values over 28.8 percent (!).

    #3 Cadmium telluride thin film cells

    As new compounds are used for the creation of solar cells, new methodologies are also evolving around the manufacturing process to provide high efficiency solar cells.

    The solar energy market is ruled by silicon semiconductors, included even in the design of thin film solar panels, but in the short to medium term, new photovoltaic materials like cadmium telluride are starting to gain their the market, as promising materials for the development of thin film panels.

    The obstacle for their large-scale market introduction arises during the manufacturing process.

    Some components seem to be very unstable because cadmium chloride has to be used during the manufacture. However, a new manufacture approach could deliver positive results, if cadmium chloride gets replaced with magnesium chloride [9].

    Unlike cadmium chloride, magnesium chloride is abundant and low cost resource that can be obtained from the seawater. This material can also boost efficiency of the thin film panels up to 15 percent.

    #4 Perovskite, the wonder material

    The ultimate and most promising technology for improvement of efficiency is the perovskite component.

    Perovskite, a compound of calcium, titanium and oxygen, offers the possibility to achieve efficiency levels above the current maximum of 22 percent at lower manufacturing costs.

    The secret lies in the low costs of raw materials and fabrication methods (printing techniques) that do not require high temperatures and such a high precision as the silicon cells do.

    How to easily improve efficiency of solar cells

    When you would like to improve efficiency of your solar cells, you should consider the effect of factors discussed above. As you can see, there are some factors that cannot be influenced by you, such as weather and outdoor temperature, but some other factors can be controlled or selected to obtain the best possible efficiency.

    The key to success is trying to tackle the factors that can be controlled.

    For example: regular solar panel maintenance helps eliminate snow, dust, dirt and ice – all of which obstruct sunlight from effectively reaching the panel’s surface, and therefore reduce efficiency of solar cells.

    By keeping your panels clean, you can nicely maintain their efficiency.

    Other factors such as the type of a solar panel, its orientation, and the minimum shade configuration are crucial parameters that will determine overall efficiency in the long run.

    Some important details that need to be considered are:

    • the solar irradiation value in your area;
    • average Cloud density;
    • levels of air pollution;
    • the angle of solar panels depending on their location and a selected mounting system.

    These parameters are generally selected by a solar designer but that does not mean that you cannot intervene in the process, especially in the selection of the solar panel type.

    Questions you may have about solar panel efficiency

    We have discussed the limits of the conversion of sunlight into electricity for silicon p-n junction cells; the overall effect of several factors on the efficiency of solar panels; the new promising technologies or proposals to elevate such efficiency values and the options that you can implement to improve the efficiency conversion of your photovoltaic system.

    Nevertheless, we haven’t discussed what exactly the use of solar panels with higher or lower efficiency values means for you. Efficiency is associated with the ability of solar cells to produce the maximum amount of electricity from a light energy source.

    A single cell with low efficiency will produce less power than another cell of the same size but with higher efficiency.

    Does it mean that if my solar panels have low efficiency they will produce less power?

    If you select a solar panel with a power output of 200 watts and an efficiency of 14 percent, and then choose another solar panel with the same power output but with an efficiency of 20 percent, both panels will produce the same 200 watts output!

    Where is the difference then?!

    The difference lies in the size of the panel–lower efficiency panels require more space to produce the same power output. This means that a 14 percent efficient solar panel will be bigger in size.

    So, the question that arises is…

    Does solar panel efficiency matter?

    The answer is: it depends. In some applications like solar cars, satellites, lighting and electronic devices size will matter, as the space availability is limited, and each inch of the panel needs to produce the maximum possible power to supply the required load.

    Utility-scale projects must also take into the account optimal selection of the size and efficiency, as bigger panels require higher installation costs due to the longer wiring and stronger mounting structures (along with higher land rental costs) [11].

    However, in residential solar systems, the availability of space on a roof or in a courtyard is sufficient to supply the desired load. Even though, this also depends on your expectations–meaning that if the demanded energy load exceeds the available space for the installation, high efficiency solar panels should be considered.

    It is important to highlight that you should settle the balance between costs, efficiency, power load and space with your solar installer at the beginning because this decision will affect the overall performance of your solar system and the total cost of your project.

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