Exploring a New Transparent Solar Cell Breakthrough

Sponsored by Brilliant. Among the renewable energy sources, solar energy is growing rapidly and leading the world towards a low carbon future. We have seen a wave of innovations in this area, such as perovskite solar cells, solar tiles and roofs , and organic panels. But what if we could get solar energy from windows and skylights in our homes and skyscrapers, or even from car windows and cell phone screens? Let's explore transparent solar panels and how they stack up against traditional panels. Could transparent solar cells be the future of solar energy? Or is the future not so clear I'm Matt Ferrell…welcome to Undecided. In modern society, we see glass everywhere, ranging in size from a small mobile phone screen to huge windows and skyscraper facades. It is estimated that there are 5-7 billion square meters of glass surfaces in the United States…so imagine that number for the whole world.

And in most buildings, these large areas of glass remain an unused energy source. According to the International Energy Agency (IEA), the building and construction sector adds up to a third of the world's total energy consumption . This represents 40% of the total direct and indirect carbon emissions into the atmosphere. And while we've seen some progress there, which I talked about in an earlier video , there is still a long way to go to decarbonize buildings around the world. Designs that use passive heating, natural lighting through triple-glazed windows and the use of solar panels on the roofs look great, but what if we could go further? What if we could harness all the potential of solar energy running through glass facades and windows, not just to provide natural lighting and heating, but to produce electricity? Insert the transparent solar panels.

Photovoltaic glass, as this technology is also called, is a type of transparent solar panel, and unlike traditional monocrystalline or polycrystalline silicon panels…opaque… this new technology is manufactured to provide a certain level of transparency. In theory, these panels could be used on anything from small portable devices like cell phones and laptops to huge windows for skyscrapers. But while standard solar panels absorb visible light to produce energy, truly transparent solar panels work on a counter-intuitive idea: capture invisible light and allow visible light to pass through. The term "transparent solar panel" makes most of us think of something as transparent as a glass window, which is a bit misleading. Technically, this term can refer to both the panel that can be fully or only partially visible, so let's take a look at the two types of transparent solar panels. ** 1) Partially Transparent Solar Panels ** These panels are manufactured using a thin-film technology where very thin layers of semiconductor material are deposited over a sheet of glass.

Another sheet of glass is then affixed to the top to form a delicious semiconductor sandwich. These extremely thin layers of semiconductor material (and we're talking about a few microns thick) is what makes these solar panels go transparent, and each layer you add increases the opacity a little bit. While current silicon panels, such as those on your roof, achieve efficiencies above 20% , standard thin-film solar panels are much lower at around 7-10%. A great application of partially transparent solar panels is in office buildings where sunlight is intense, so the panels are installed to reduce the level of sunlight entering the building. When designing windows and skylights. SHGC basically measures the amount of available solar heat that can pass through the glass. The higher this ratio, the more heat enters the building. The SHGC of Onyx panels, one of the leading manufacturers of transparent photovoltaic glass for buildings, ranges from 10% to 40%, which limits the sun's heat entering the building while simultaneously producing electricity. ** 2) Fully Transparent Solar Panels ** The dream of having solar panels that look like regular glass began with a group of researchers at Michigan State University (MSU), who created the first fully transparent solar cell in 2014.

The team created the transparent luminous solar concentrator (TLSC), which uses organic salts to capture only a certain portion of the solar spectrum that contains specific wavelengths of invisible light, such as ultraviolet (UV) and infrared (IR), while allowing normal visible light to pass through. . When sunlight hits the panel, the UV and IR lamps are converted into a different type of infrared ray that lights up. This new wavelength is then transmitted to the edges of the window, where it is converted into electricity by the solar cells. Since the materials do not absorb or emit light in the visible spectrum, they appear transparent to the human eye. The transparent solar panels created by the researchers achieved a transparency level of 86%. Unfortunately, the efficiency of this prototype was very low (less than 1%), but they said that there is a possibility to reach an efficiency of 10%. Compared with traditional silicon-based crystal panels, it is obviously a big negative that the efficiency of transparent solar panels is very low. But when it comes to solar panels, efficiency is not everything. The lower efficiency of the transparent solar panels means that we will need more covered area in order to produce the same amount of energy as the rooftop solar array with 20% efficiency.

However, due to how transparent solar panels are integrated into buildings, there is more potential surface area to compensate for this lower efficiency. An interesting feature of partially transparent solar panels is that thin-film solar cells can achieve high efficiencies even when they are not at the optimum angle of inclination, which is great for buildings and skyscrapers where windows are installed vertically. Thin-film cells are more heat-tolerant, having a lower efficiency drop than conventional crystalline silicon solar panels at high temperatures. Fully transparent solar panels have a distinct advantage over partially transparent versions, as they can turn any pane of glass or window into a photovoltaic, look better, and have a wide range of use cases. But its big drawback is not only its low efficiency. Transparent solar panels use organic solar cells, which degrade more quickly than inorganic solar cells. Thin films, for example, last from 10 to 20 years, while panels based on crystalline silicon have an average life of 25 years.

Although there are still many improvements to be made, the benefits and the wide range of applications…mainly in the construction sector… have prompted companies around the world to explore the technology. But before we get to where we're seeing this technology emerge today, if you're interested in learning more about the principles behind solar energy, I highly recommend checking out Brilliant's Solar Cycle. It's a fun and practical approach that really helped me wrap my head around some basic pillars of how solar energy works.

Everything from the basics of photovoltaics to solar thermal energy and photon absorption. It's a really good idea. But even if this cycle doesn't fire up your mind, there will be something else you will enjoy. They have over 60 courses including topics in scientific reasoning , quantum mechanics, and applied science. They have something for everyone. All concepts are taught through fun and interactive challenges to help you understand the 'why' of something… not just the 'how'. It helps develop your intuition, which is my favorite part about Brilliant and taps the way I learn…and makes it fun. Go to www.brilliant.org/ Not yet decided to register for free. The first 200 people will get 20% off their annual premium membership. Thank you, Brilliant, and all of you for your support. So back to where we see it…or don't see it… the transparent solar panels appear. Onyx Solar is one of the leading manufacturers of transparent PV glass for buildings. The company offers two solar glass technologies, one based on amorphous silicon, and another on crystalline silicon, with options ranging from 0% transparency up to 38%.

Portions of using layers of heat-treated safety glass can be customized to specific projects that fit in anything like walls, curtains, blinds, or even floors, but I'll step on that in a minute. An interesting project using Photovoltaic Skylight is the McDonald's Flagship restaurant in Walt Disney, Florida. The building has become a zero-energy building and the first zero-emission restaurant in the US. The system is expected to produce more than 2 million kilowatt-hours of electricity over 35 years and will have a payback time in less than 4 years. Another product from Onyx is its photovoltaic interface. Among its projects, the company has created a frontage for the headquarters of FEMSA, the largest Coca-Cola bottling company in the world (Monterrey, Mexico). It consists of 370 large-size gray amorphous silicon glass units with 20% transparency, and can produce about 17,200 kWh of energy. Overall, this project is expected to have a payback time of less than one year and reduce HVAC energy demand by 24%. But you can also take a big step into the future… and on a PV floor… by using the company's PV floors. They are designed for use in pedestrian traffic and can carry up to 400 kg (about 880 lb).

Furthermore, they can be customized in a wide range of colors and use the same installation procedures as metal frames and wood floors. One project that has gained momentum is a Manhattan penthouse that used 50 glass plots for an innovative balcony and solar energy harness. The photovoltaic system reduced 19% of the penthouse's HVAC requirements and produces green electricity at a cost of approximately $0.012. Talk about walking on the bright side. And when it comes to cost, their photovoltaic glass is about $50 per square meter, while typical solar panels typically cost around $40-110 per square metre, a typical double window costs around $24–45 per square metre here in Massachusetts… including Including material and installation costs. As cool as they are, the transparency levels aren't good enough for applications where you need clear windows that look like regular glass. So, you might want to take a look at Australia-based ClearVue, which has been making clear solar panels…with a slight tint…and has no optical distortion, achieving 70% transparency. Their technology consists of several layers, but in short, their glass system consists of nano and micro-microscopic layers spread over a thin layer located within panes of glass.

The price per square meter for a low-emission, insulated triple-glazed unit from ClearVue is $400. Comparatively, a common three-pane window is $270-430 per square metre. One of their projects was the Warwick Shopping Center Lounge in Perth, Australia. The installation includes 18 triple-glazed, low-e PV panels that provide energy for indoor lighting, outdoor signage, and the shopping center display. According to an article from the company, each solar window in this building was capable of producing approximately 0.1 kWh from 6-7 hours of sun. Depending on the project, the company estimates that the payback period can be as low as a year. The carbon yield is less than 9 years, compared to 100 years for typical double-glazed windows . They claim that by using inorganic materials, these PV windows can produce energy for more than 20 years, with an efficiency loss of 0.5% per year.

But again… when we go back to efficiency, it's not that great. Today, an industry standard 3.5 x 1.6 meter solar window can give 30 W/m² while a typical 340 W solar panel can give about 200 W/m². This means to produce the same power from a rooftop PV system, we need six times more surface area for these transparent solar panels to equal. But there is where we come back to some of the interesting research that is being done. With the goal of increasing efficiency, the University of Michigan and the team led by Stephen Forrest obtained interesting results. They have been exploring the use of organic materials in the panels, but the main challenge is how to prevent rapid deterioration.

To get around this problem, the team added layers to the sun-facing side of the glass. They have tried multiple substances in different tests, but the most recent one with fullerene has shown some hope. They tested this new transparent solar panel under several conditions, such as simulating sunlight that can illuminate the equivalent of one sun up to 27 suns, and temperatures of up to 150 degrees Fahrenheit (65 degrees Celsius). The conclusion was that solar cells could still save 80% of their energy even after 30 years. They have also achieved 40% transparency and believe it is possible to increase this number to 60%. They are also working hard to raise the efficiency of 10% up to 15% in the highest transparency.

It's not hard to see that transparent solar panels still face a difficult path to full transparency with higher efficiencies (or at least efficiencies closer to typical solar panels), and energy density at reasonable market costs. Today, with an efficiency of less than 10% and a power density of 30 W/m², this technology still requires much more space to produce the same amount of energy that rooftop PV systems can provide. But it's also important to remember that the University of Michigan increased the original efficiency <1% in 2014 to about 10% in 2021.

This is very important and exciting… I hope the technology becomes more cost-competitive over time. what do you think? Do you think we'll see transparent solar power in most of our buildings… maybe even cars, laptops, and smartphones in the future? Jump to the comments and let me know. Thank you, as always, to my patrons. Their direct support really helps with the production of these videos. Speaking of which, if you liked this video, be sure to check out one of the videos I linked here. Subscribe and hit the notification bell if you think I've won it. Thanks so much for watching and I'll see you next time.

^ onyx_façade: light-ventilated facade and roof.

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