One of the main obstacles to large-scale solar deployment is having enough space for solar panels, especially in cities where land and rooftop space are scarce. In high-density locations, generating enough solar energy to power a building from the roof alone is difficult, especially when mechanical systems take up space. But what if glass alone could generate clean energy using transparent solar panels?
Michigan State University (MSU) developed the first fully transparent photovoltaic (PV) panels in 2014. These panels are suitable for transparent windows and even touch screens on devices because they do not absorb visible sunlight, creating a new paradigm for solar energy.
Although transparent solar panels are less efficient than monocrystalline and polycrystalline solar cells, there are many potential applications due to their functionality, such as windows in cars, glass in skyscrapers and even touch screens in cell phones. Researchers are working to improve the technology of transparent solar panels to make them commercially viable on a large scale.
History of transparent photovoltaic panels.
MSU researchers have used organic salts to absorb invisible wavelengths of light, including infrared and ultraviolet light. This approach allows the solar glass to act like typical glass, while generating solar energy as visible light passes through it. Then in 2020, researchers from the United States and Europe developed transparent solar panels with 100% transparency.
“Highly transparent solar cells represent the wave of the future for new solar applications,” – said Richard Lunt, Johansen Crosby Endowed Associate Professor of Chemical Engineering and Materials Science at MSU. “We’ve analyzed their potential and shown that by harvesting only invisible light, these devices can provide similar power generation potential as rooftop solar panels, while providing additional functionality to increase the efficiency of buildings, cars and mobile electronics.”
Unfortunately, the efficiency of transparent solar panels is quite low, currently at around 1%, but their potential is estimated at 5%. While this is very low, the potential applications of solar glass mean that it can be widely used in many applications, making it extremely practical in other ways.
“MSU has our first installation external to the company,” – lunt said. “We have dozens of projects currently being installed around the world from our pilot line. Now we are preparing for commercial production lines that will be truly transformational.”
Partially transparent photovoltaic panels.
A German startup called Heliatek GmbH has developed partially transparent solar panels that absorb 60 percent of the light they receive. The efficiency of the partially transparent solar panels, also known as semi-transparent solar panels, is 7.2 percent, which is still much lower than that of traditional solar panels.
Semi-transparent solar technology has a lower efficiency because 40 percent of the light is not absorbed, making it partially transparent. However, semi-transparent solar glass can be ideal for specific applications where tinted glass is desirable, such as solar windows on the south wall of buildings.
Translucent photovoltaic panels.
Semi-transparent photovoltaic panels are a specific type of transparent solar panels with light transmission of less than 100%. Although fully transparent solar panels are available, semi-transparent modules are now more common on the market.
These semi-transparent panels are particularly well suited for applications such as building windows and greenhouses, where a certain level of light filtration is desired. However, for devices such as smartphones that require 100% light transmission, translucent panels may not be the ideal choice.
How do transparent solar panels work?
Solar panels absorb sunlight (photons) and convert it into electricity (electrons). This transparent solar panel technology acts like a transparent solar concentrator and absorbs light that is not visible to the naked eye, including certain UV and infrared wavelengths. However, visible light does pass through, so potentially any glass window can be converted into a photovoltaic cell.
Transparent solar panels typically consist of multiple layers. These layers are designed to capture sunlight and convert it into electricity while remaining transparent. The specific composition and number of layers can vary depending on the manufacturer and the technology used, but typically include transparent conductive layers, semiconductor layers and protective coatings. These layers work together to allow the panel to generate electricity while allowing light to pass through.
What are some applications of transparent photovoltaic panels?
Transparent solar panels transmit light while generating electricity and have a number of potential applications, including:
- Building-integrated photovoltaics (BIPV): Glass solar panels can be integrated into the windows, facades and skylights of buildings, transforming them into functional energy-generating surfaces without obscuring natural light.
- Greenhouses: Transparent solar panels can be integrated into greenhouse structures, allowing plants to receive sunlight while generating electricity to power greenhouse operations.
- Consumer electronics: Transparent solar panels can extend battery life or provide additional power for electronic devices such as smartphones and tablets.
- Automotive: Transparent solar cells can be integrated into the windows or sunroofs of vehicles, meeting the electricity needs of electric or hybrid vehicles.
- Outdoor furniture and shelters: Transparent solar panels can be applied to outdoor structures such as bus shelters, benches or pavilions, providing shade while generating renewable energy.
- Portable chargers: Transparent solar cells can be incorporated into portable chargers, allowing users to use solar energy to charge devices on the go.
- Military and emergency applications: Glass solar panels can be used in military and emergency applications, providing power for field operations, shelters or communications equipment.
- Aerospace: Transparent solar cells can be integrated into the surfaces of spacecraft or satellites, meeting their energy needs in space.
- Consumer products: Various consumer products, such as wearables, backpacks and even clothing, offer a discreet way to generate energy from transparent solar panels.
- Public spaces and infrastructure: Transparent photovoltaic panels can be integrated into public spaces such as bus stops, sidewalks or canopies, combining functionality with sustainable energy generation.
Companies producing transparent photovoltaic panels.
Several companies are actively involved in the development and production of transparent solar technologies. Leading manufacturers in the transparent solar panel industry include:
California-based Ubiquitous Energy has made significant progress in the development of transparent solar cells for commercial applications. Their ClearView Power™ technology is designed to offer transparent solar windows for buildings. The company has focused on increasing the transparency and efficiency of its solar cells, making them well suited for architectural integration.
In the UK, Polysolar specializes in transparent photovoltaic glass tailored for building integration. The company has been actively involved in various projects, including the installation of transparent solar canopies and building-integrated photovoltaic (BIPV) solutions in urban environments.
The Spain-based company is known for its innovative building-integrated solar products and solar panel window solutions. Onyx has dedicated itself to creating transparent solar panels suitable for use in skylights, canopies and facades. These solutions enable the generation of electricity while allowing natural light to pass through.
Bright Solar, a forward-thinking company, has made significant strides in developing solar glass products suitable for commercial applications. Their cutting-edge technology aims to provide innovative solutions for building integration. Bright Solar has focused on increasing both the transparency and performance of its solar glass, making it ideal for seamless architectural integration.
SolarScape has become a leader in the development of solar glass products for commercial applications. Their transparent solar panel technology aims to revolutionize building integration solutions. SolarScape aims to enhance both the performance and transparency of solar glass for seamless architectural integration.
The company is a major player in the renewable energy sector, particularly in BIPV. The company has demonstrated a commitment to innovation in developing cutting-edge BIPV products that seamlessly integrate solar technology with architectural elements, including glass curtain walls and sunrooms.
Known for its power-generating transparent windows, SolarWindow Technologies is working to develop flexible, thin coatings that transform ordinary glass into power-generating windows with solar panels.
Future applications for transparent photovoltaic panels.
It is estimated that there are 5 to 7 billion square meters of glass surfaces in the United States, so the possibilities for solar glass are almost limitless. This means that windshields and sunroofs in cars, smartphone screens, curtain walls and building canopies can generate solar energy.
“When you realize you can do this, you can make a solar cell that looks like a window, it really sparks the imagination,” Lunt said.
If this new technology is implemented in glass on skyscrapers, there is more potential to generate a significant amount of solar energy because there are so many vertical surfaces on tall buildings. In addition, the angle at which the sun falls on the transparent solar panels is not as critical.
Traditional photovoltaic panels vs. transparent photovoltaic panels.
Because the two technologies are so different, their ideal applications are also so different. For example, if a solar contractor wants to generate as much energy as possible in a limited space, traditional photovoltaic panels are a better option because they are much more efficient. However, when a transparent photovoltaic product is needed, transparent solar panels have a clear advantage. If transparent photovoltaic products become widespread, it will be difficult to distinguish them from conventional materials.
“The reality of climate change means we need to find more ways to harness renewable energy,” – lunt said. “Transparent solar glass greatly expands the possibilities for harnessing solar energy and changes the way we think about energy generation. There is no longer a trade-off between aesthetics and renewable energy. You can turn almost any surface of a building or landscape into a solar panel and generate energy where you use it, without even knowing it’s there.”
But transparent solar panels are still evolving rapidly, so what may be true today may be different a decade from now. For example, engineers at MSU have now developed transparent solar panels with a zinc oxide layer that they predict will last three decades, so the potential lifespan of the two technologies is comparable.
Like traditional solar modules, transparent solar panels produce no greenhouse gas emissions during energy production and help reduce reliance on polluting fossil fuels. Currently, just over 3 percent of electricity in the United States is generated from the sun. But as the world shifts to cleaner forms of energy, innovation is needed to enable solar power to generate a larger share of the total energy mix.
While traditional solar panels are ideal for rooftops and solar farms, there are other applications where they fall short, especially in high-density areas where lightweight solar cells are needed. In addition to larger-scale deployment, energy storage capabilities are also needed to ensure that solar power can provide baseload power throughout the day, regardless of the weather.
Advantages of traditional photovoltaic panels:
- Highest energy conversion efficiency with commercially available solar panels with efficiencies exceeding 22 percent
- More mature technology that has been extensively tested over decades, meaning real-world performance is easier to predict
- Available for large-scale deployment thanks to robust manufacturing capabilities in many countries
- Transparent glass solar panels must be handled with more care than traditional solar panels to avoid breakage, as glass is more fragile
Advantages of transparent photovoltaic panels:
- Ideal for urban areas where space for traditional solar panels is limited, as all transparent building surfaces can generate energy
- Aesthetic advantages, as solar glass integrates seamlessly into buildings and other applications, so the difference between traditional glass and fully transparent solar glass is imperceptible
- The angle of the sun’s rays on the surface is irrelevant, which expands the application possibilities
- Mobile electronics can use ambient light to partially charge their own batteries, which would be attractive to consumers
- Solar glass can serve two functions when integrated into buildings, making efficient use of resources
- Transparent solar cells themselves are lightweight and portable (before being applied to glass)
Are there transparent photovoltaic panels?
Transparent solar panels, often called solar windows, are new technologies in the field of solar energy. Researchers are exploring various approaches, including organic photovoltaic cells, thin-film technologies, dye-sensitized solar cells, transparent silicon and quantum dot solar cells, to create solar panels with varying degrees of transparency. However, despite the progress toward fully transparent high-efficiency solar panels, they are not widely available on the market.
Are transparent solar panels as efficient as traditional photovoltaic panels?
No, transparent solar panels are generally less efficient than traditional solar panels. They have the advantage of being translucent, which allows light to pass through, but this feature is often associated with lower energy conversion efficiency. Scientists are actively working to improve the energy efficiency of transparent solar technology, but for the time being it does not match the performance of conventional opaque solar panels.
What do transparent solar panels mean for the future of photovoltaic energy?
If transparent solar panels become commonplace, their potential applications will be endless. Engineers and solar specialists will need to understand how to successfully implement the technology in electronics, cars, buildings and other applications. Similarly, architects and contractors will need to know how to incorporate transparent solar products into building facades to maximize renewable energy production.
As the solar industry advances, solar professionals need to stay on top of the latest technologies to help drive innovation. There are many promising solar technologies on the horizon that could change the future of the clean energy movement, including liquid solar panels and the use of perovskite as a semiconductor in solar modules to replace or minimize the use of silicon. Thus, future scientific breakthroughs will shape the future of clean energy worldwide.