Transparent Solar Panels: What This Emerging Technology Could Mean For Installers

One major hurdle to wide-scale solar energy deployment is having enough space for solar panels, especially in cities where land and roof space on buildings is in short supply. In high-density areas, producing enough solar electricity to power a building from just the rooftop is difficult, especially when mechanical systems occupy space. But what if the glass itself could generate clean energy?

Transparent photovoltaic (PV) panels were first developed in 2014 by Michigan State University (MSU) and are the first fully transparent solar panels. This means they are suitable for clear windows and even touch screens because they don’t absorb visible sunlight, creating a new paradigm for solar power.

Although they are less efficient than monocrystalline and polycrystalline solar cells, there are many potential applications due to their functionality, such as the windshields on cars, the glass in high-rises, and even the touch screens on cell phones. Researchers are working to advance this technology to be commercially viable on a large scale.

The Story On Transparent Solar Panels

Researchers at MSU used organic salts to absorb invisible wavelengths of light, including infrared and ultraviolet light. This approach allows the solar glass to perform like typical glass, while it also generates solar energy because the 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, the Johansen Crosby Endowed Associate Professor of Chemical Engineering and Materials Science at MSU. “We analyzed their potential and show that by harvesting only invisible light, these devices can provide a similar electricity-generation potential as rooftop solar while providing additional functionality to enhance the efficiency of buildings, automobiles and mobile electronics.”

Unfortunately, the efficiency of transparent solar panels is quite low and is currently around 1 percent, but it has an estimated potential of 5 percent. Although this is very low, the potential applications in solar glass mean it could be widely used in numerous applications, making it incredibly practical in other ways.

“MSU has our first installation external to the company,” Lunt said. “We have dozens of projects that are now getting installed around the world from our pilot line. We’re now gearing up for commercial-size production lines, which will be truly transformative.”

In addition, a German startup named Heliatek GmbH developed partially transparent solar panels, which absorb 60 percent of the light they receive. The efficiency of partially transparent solar panels is 7.2 percent, which is still significantly lower than traditional solar panels.

This technology has a lower efficiency because 40 percent of the light is not absorbed, thus making it partially transparent. However, partially transparent glass can be ideal for specific applications where tinted glass is desirable, such as solar windows on the south face of buildings.

How Do Transparent Solar Panels Work?

Solar panels absorb sunlight (photons) and convert them into electricity (electrons). This see-through technology functions as a transparent solar concentrator and absorbs light that isn’t visible to the naked eye, including specific UV and infrared wavelengths. However, visible light passes through, so potentially any glass window could be converted into a photovoltaic cell.

Future Applications For Transparent Solar Cells

It’s estimated that there are 5 to 7 billion square meters of glass surfaces in the United States, so the opportunities to use solar glass are nearly limitless. This means that the windshields and sunroofs on cars, smartphone screens, curtain walls, and canopies on buildings can all generate solar power.

“Once you realize you can do this, you can make a solar cell that looks just like a window, it really sparks your imagination,” said Lunt.

If this new technology is implemented in the glass on skyscrapers, there is a greater potential to generate a significant amount of solar energy because there are so many vertical surfaces on tall buildings. Also, the angle that the sun hits transparent solar panels isn’t so critical.

Comparing Traditional Photovoltaic Panels To Transparent Cells

Because the two technologies are so different, so are their ideal applications. For example, if a solar contractor wants to generate as much energy as possible in a limited space, traditional solar PV panels are a better option because they have much higher efficiency. Yet, when a see-through product is needed, transparent solar has a clear advantage. If clear solar products become widespread, it will be difficult to tell them apart from conventional materials.

“The realities of climate change mean we need to find more ways to use renewable energy,” Lunt said. “Transparent solar glass expands the options of solar power tremendously and changes the way we think about generating power. There is no longer a tradeoff between aesthetics and renewable energy. You could turn nearly every surface of a building or landscape into a solar array and generate power right where you use it without even knowing that it’s there.”

However, transparent solar panels are still rapidly advancing, so what might be true today might be different a decade from now. For example, engineers at MSU have now developed transparent solar panels with a zinc-oxide layer they expect will last for three decades, so the potential lifespan of both technologies is comparable.

Like traditional solar modules, clear solar panels produce no greenhouse gas emissions when producing energy and help reduce reliance on polluting fossil fuels. Currently, just over 3 percent of the electricity in the United States is generated from the sun. But as the world transitions to cleaner forms of energy, innovation is needed to enable solar power to produce a larger share of the total energy mix.

Although traditional solar panels are excellent for rooftop applications and solar farms, there are other applications where they falter, especially in high-density areas when lightweight solar cells are needed. In addition to more widescale deployment, energy storage capabilities are also needed to ensure that solar energy can provide baseload power throughout the day, regardless of the weather.

Advantages of traditional solar cells:

• Superior energy conversion efficiency with solar panels on the market that exceed 22 percent efficiency

• A more mature technology that has been extensively tested for decades, which means real-world performance is easier to predict

• Available for widescale implementation today due to a robust manufacturing capacity across numerous countries

• The transparent glass solar panels needs to be handled with more care than traditional solar panels to avoid breakage because glass is more fragile

Advantages of transparent solar cells:

• Ideal for urban areas where space for traditional solar panels is limited because all the transparent surfaces of a building could generate power

• Aesthetic advantages because solar glass seamlessly integrates into buildings and other applications, so the difference between traditional glass and fully transparent solar glass is undetectable

• The angle of the sun to the surface isn’t important, expanding the options for deployment

• Mobile electronics can use ambient light to partially recharge their own batteries, which would be attractive to consumers

• Solar glass can fulfill two functions when integrated into buildings, thus using resources efficiently

• The transparent solar cells themselves are lightweight and portable (before applying to glass)

What Do Clear Solar Panels Mean For The Future Of Solar?

If transparent solar panels become widespread, their potential uses are endless. It will be necessary for engineers and solar professionals to understand how to effectively implement this technology in electronics, automobiles, buildings, and other applications. Likewise, architects and contractors will need to know how to incorporate see-through solar products into building facades to maximize renewable energy production.

As the solar energy industry advances, solar professionals must stay current on the latest technology to help drive innovation. There are numerous promising solar technologies on the horizon that could alter the future of the clean energy movement, including liquid solar panels and using 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 across the globe.

Want to learn about other evolving trends in clean energy? Check out the GreenLancer blog!