HOW SCIENTISTS ARE TURNING ORDINARY WINDOWS INTO ELECTRICITY GENERATORS: INVISIBLE SOLAR PANELS
Could the windows of your home, office, shopping mall or skyscraper one day generate electricity without blocking your view?
An innovative development in solar energy research is bringing this possibility closer to reality. Researchers led by Richard Lunt at Michigan State University (MSU) in the United States have helped develop transparent solar technology that can convert ordinary-looking glass surfaces into electricity-generating materials.
Unlike traditional solar panels, which use dark photovoltaic cells to capture sunlight, this technology is designed to allow visible light to pass through the glass while capturing selected invisible wavelengths of sunlight.
This means that windows could potentially serve two purposes simultaneously: allowing natural daylight into buildings and generating renewable electricity.
The development could open up new opportunities for sustainable architecture, energy-efficient buildings, electric vehicles and even electronic devices.
What Are Invisible Solar Panels?
Invisible solar panels, commonly described as transparent solar panels or transparent photovoltaics (TPV), are an emerging type of solar energy technology designed to generate electricity while maintaining the transparency of glass.
Traditional solar panels usually contain dark photovoltaic cells that absorb visible sunlight and convert it into electrical energy. Although highly useful, their appearance and structure make them unsuitable for many applications where transparency is required.
Transparent solar technology attempts to overcome this limitation.
Instead of absorbing most of the visible light, certain transparent solar systems are designed to selectively capture ultraviolet (UV) and near-infrared (NIR) wavelengths, which are invisible to the human eye.
The technology developed by researchers associated with Michigan State University uses specially designed light-absorbing materials to capture these wavelengths and convert the collected energy into electricity.
As a result, the glass can remain visibly clear while functioning as a solar energy generator. (Michigan State University, MSU Innovation Center, MIT Technology Licensing Office)
2. Who Developed This Transparent Solar Technology?
One of the leading researchers behind this technology is Dr. Richard Lunt, a scientist and professor of Chemical Engineering and Materials Science at Michigan State University.
Lunt and his research team pioneered the development of a technology known as the Transparent Luminescent Solar Concentrator (TLSC).
Their research attracted international attention because it demonstrated a potential way to generate solar electricity from transparent surfaces without significantly affecting the amount of visible light passing through them.
In August 2014, researchers led by Lunt published details of their transparent solar concentrator development. The research demonstrated how specially designed materials could capture non-visible sunlight and direct the resulting light towards photovoltaic cells positioned around the edges of a transparent surface. (www1.udel.edu, Michigan State University, UD College of Engineering)
Lunt is also a co-founder of Ubiquitous Energy, a company working to commercialise transparent solar technology.
How Do Invisible Solar Panels Actually Work?
The science behind transparent solar panels is particularly interesting because the technology uses light that human eyes cannot see.
To understand how it works, it is useful to know that sunlight contains different types of electromagnetic radiation.
These include:
- Visible light: The portion of sunlight that human eyes can see.
- Ultraviolet (UV) light: Invisible radiation with wavelengths shorter than visible violet light.
- Infrared light: Invisible radiation with wavelengths longer than visible red light.
Traditional solar panels generally absorb a broad range of sunlight, including visible wavelengths.
However, the transparent luminescent solar concentrator developed by Lunt's team uses specially engineered organic molecules to selectively absorb ultraviolet and near-infrared light.
The process can be explained in four stages.
Step 1: Sunlight reaches the transparent glass
When sunlight falls on the specially treated transparent material, visible light passes through, allowing people to see through the window.
Step 2: Invisible wavelengths are captured
Special organic molecules within the material absorb selected ultraviolet and near-infrared wavelengths.
Step 3: Light is redirected towards the edges
The absorbed energy is re-emitted at wavelengths that can travel through the transparent material towards its edges through a process known as light guiding.
Step 4: Solar cells generate electricity
Small photovoltaic cells positioned around the edges capture the redirected light and convert it into electrical energy.
This arrangement allows the main glass surface to remain transparent while the solar cells are concentrated around its boundaries. (Michigan State University, MIT Technology Licensing Office, www1.udel.edu)
What Makes This Technology Different from Traditional Solar Panels?
Transparent solar panels and conventional solar panels both use photovoltaic technology to generate electricity. However, their designs and potential applications are different.
Feature Traditional solar panels Transparent solar panels
Appearance Usually dark and opaque Designed to be transparent
Light absorption Broad sunlight absorption Selective light absorption in certain designs
Installation Rooftops, solar farms and open spaces Windows, glass facades and transparent surfaces
Visibility Blocks the view behind the panel Allows people to see through the glass
Main purpose Generate electricity Generate electricity while maintaining transparency
An important distinction is that not every transparent solar technology works in exactly the same way. Some use luminescent solar concentrators with photovoltaic cells at the edges, while others use thin photovoltaic layers directly integrated into glass.
The main objective is to make solar energy generation possible in places where conventional solar panels cannot easily be installed.
Michigan State University Has Already Installed Transparent Solar Glass
One of the most interesting developments is that this technology has moved beyond experimental research.
On August 25, 2021, Michigan State University announced the installation of transparent solar glass panels at its Biomedical and Physical Sciences Building.
The installation covered approximately 100 square feet of transparent solar glass above the building's entrance.
According to the university, the installation was expected to generate enough electricity to power the lighting in the building's atrium.
The panels were developed and manufactured by Ubiquitous Energy in collaboration with Richard Lunt and Michigan State University.
The installation was particularly significant because it demonstrated how transparent solar technology could be incorporated into an existing university building rather than being limited to laboratory experiments.
The university described it as the first installation of this technology at a university and the first building deployment outside Ubiquitous Energy and its commercial partners. (Michigan State University, Infrastructure Planning and Facilities, MSU Innovation Center)
This real-world installation provides an important example of how future buildings could potentially generate electricity through their windows and glass structures.
Where Could Transparent Solar Panels Be Used in the Future?
One of the biggest advantages of transparent solar technology is its potential to utilise surfaces that are already part of everyday infrastructure.
Here are some possible applications.
1. Skyscrapers and Commercial Buildings
Modern cities contain thousands of buildings with large glass windows and exterior facades.
Transparent solar panels could potentially transform these surfaces into electricity-generating structures.
Instead of using glass only for lighting and architectural design, buildings could also use it to generate a portion of their electricity requirements.
This concept is particularly important for high-rise buildings, where available rooftop space is often limited compared with the total area of windows and glass facades.
2. Residential Homes
In the future, homeowners may be able to install transparent solar glass in windows, doors and other suitable glass surfaces.
This could help generate additional electricity while maintaining natural lighting and visibility.
Such systems could potentially work alongside conventional rooftop solar panels to increase the amount of solar energy a house can collect.
3. Cars and Electric Vehicles
Vehicle manufacturers could potentially integrate transparent solar technology into sunroofs, windows and other glass components.
The electricity generated could support selected vehicle electrical systems or help reduce the energy demand on the main battery.
However, the actual contribution would depend on the available glass area, sunlight exposure and the efficiency of the solar technology.
4. Smartphones and Electronic Devices
Transparent solar materials could also have applications in electronic devices.
For example, certain transparent surfaces on smartphones, tablets and other portable electronics could potentially collect solar energy.
This may offer an additional source of power for small electronic systems, although it would not necessarily replace conventional charging.
5. Greenhouses and Agricultural Buildings
Greenhouses require transparent materials to allow sunlight to reach plants.
If suitable transparent solar technology can be integrated without significantly affecting the light needed for plant growth, it could potentially allow agricultural buildings to generate electricity while maintaining their primary purpose.
However, the wavelengths absorbed and the effect on plant growth would need to be carefully considered.
How Could Transparent Solar Technology Benefit the Environment?
The development of transparent solar panels could contribute to the wider adoption of renewable energy.
Some potential environmental benefits include:
Better utilisation of existing surfaces
Buildings already contain extensive glass surfaces. Using these areas for electricity generation could provide additional opportunities to collect solar energy without requiring separate land for solar farms.
Reduced dependence on fossil fuels
Electricity generated from solar energy can help reduce reliance on fossil-fuel-based power generation, depending on how the electricity is used and what energy source it replaces.
More energy-efficient buildings
Transparent solar glass could become part of building designs that combine natural lighting with on-site renewable electricity generation.
Additional renewable energy capacity in cities
Urban areas often have limited space for conventional solar installations. Transparent photovoltaic technology could provide another option for generating electricity within densely populated environments.
However, the overall environmental benefits will depend on manufacturing processes, material durability, energy efficiency, installation costs and the amount of electricity generated throughout the product's lifetime.
What Are the Challenges Facing Invisible Solar Panels?
Although transparent solar technology has significant potential, it is important to understand that it still faces several technical and commercial challenges.
1. Electricity-generation efficiency
One of the biggest challenges is balancing transparency with electricity generation.
Traditional solar panels can absorb a large proportion of sunlight, whereas transparent solar panels must allow visible light to pass through. This creates limitations on how much solar energy can be collected.
2. Manufacturing costs
Producing specialised transparent photovoltaic materials and integrating them into architectural glass can be expensive.
For widespread adoption, manufacturers will need to develop cost-effective production methods.
3. Durability and maintenance
Solar windows must withstand years of exposure to sunlight, heat, humidity, rain and other environmental conditions.
Their performance must remain reliable over long periods, particularly when installed in large buildings.
4. Installation and electrical integration
Transparent solar glass needs suitable electrical connections, wiring systems and building integration.
Replacing conventional windows with electricity-generating glass may also require modifications to existing building infrastructure.
5. Commercial availability
Although companies are working to commercialise transparent solar products, their availability, pricing and suitability vary between markets.
Therefore, transparent solar panels should currently be viewed as an emerging renewable energy solution rather than a technology that has already replaced conventional solar systems.
Could Transparent Solar Panels Become the Future of Green Buildings?
The global demand for electricity continues to increase, particularly as cities expand and more buildings, vehicles and electronic devices require energy.
Conventional solar panels have already become an important part of the renewable energy industry. However, their installation is often limited by available rooftop space, building design and other practical considerations.
Transparent solar technology introduces a different approach.
Instead of depending entirely on rooftops and open land, it offers the possibility of generating electricity from windows, glass facades and other transparent surfaces.
A research perspective published in Nature Energy by Michigan State University researchers in 2017 examined the potential of highly transparent solar applications. The researchers highlighted how combining transparent solar technology with conventional rooftop solar installations could create significant additional electricity-generation opportunities.
The study also discussed the enormous potential represented by glass surfaces in buildings and other infrastructure. (Michigan State University)
If researchers and manufacturers can improve efficiency, reduce production costs and increase durability, transparent solar technology could become an important component of future sustainable architecture.
It may eventually help transform ordinary buildings into structures that not only consume electricity but also generate a portion of their own energy.
Is This Technology Already Available for Everyday Consumers?
Transparent solar technology is no longer purely theoretical. The Michigan State University installation in 2021 demonstrated that transparent solar glass can be used in a real building.
Companies such as Ubiquitous Energy are also working to commercialise this type of technology.
However, this does not mean that transparent solar windows are already widely available or affordable for ordinary households worldwide.
The technology still needs further development and broader commercial deployment before it becomes a mainstream alternative to traditional solar panels.
For countries such as Sri Lanka, where sunlight is available throughout much of the year, transparent solar technology could potentially offer interesting opportunities for future commercial buildings, hotels, shopping complexes and modern residential developments.
Nevertheless, local availability, installation costs, electricity-generation performance and suitability for tropical weather conditions would need to be evaluated before practical adoption.
The development of transparent solar panels demonstrates how scientific innovation could change the way society generates renewable electricity.
Research led by Richard Lunt and his team at Michigan State University has helped introduce a new approach to solar energy generation by using transparent materials that capture invisible wavelengths of sunlight.
With the possibility of transforming ordinary windows into electricity-generating surfaces, this technology could eventually create new opportunities for sustainable buildings, transportation and electronic devices.
Although several challenges remain before widespread adoption becomes possible, transparent solar technology represents an exciting direction in the development of renewable energy.
The future of solar power may not be limited to panels installed on rooftops. It could also be built into the windows and glass surfaces that surround us every day.
References and Further Reading
The following sources provide additional scientific and institutional information about this technology.
1. Michigan State University – Power Generation You Can See Through: Transparent Solar Panels Installed on Campus (August 25, 2021).
2. Michigan State University – Lunt in Nature Energy: Transparent Solar Technology Represents the Wave of the Future.
3. Michigan State University – Invisible Solar: Solar Energy That Doesn't Disrupt the View.
4. University of Delaware – Researchers Develop a Transparent Solar Concentrator (August 27, 2014).
5. MIT Technology Licensing Office – Transparent, Near-Infrared Luminescence Solar Concentrator for Power Generating Windows.
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