New solar panel technologies are set to transform the global solar energy landscape. Some of these promising technologies are already in the advanced stages of development, and could hit the market fairly soon. With these innovations, solar is no longer going to require extensive land parcels or unsightly roof spaces. (Aesthetically appealing and highly efficient solar shingles, for example, are already creating attractive solar roofs.)

Transparent Solar Panels/Glass by Scientists at Michigan State University
Photo: Richard Lunt / Michigan State University

What are transparent solar panels?

Photovoltaic glass is probably the most cutting-edge new solar panel technology that promises to be a game-changer in expanding the scope of solar. These are transparent solar panels that can literally generate electricity from windows—in offices, homes, car’s sunroof, or even smartphones. Blinds are another part of a building’s window that can generate electricity (we will discuss it in a later section).

Researchers at Michigan State University (MSU) originally created the first fully transparent solar concentrator in 2014. This clear solar panel could turn virtually any glass sheet or window into a PV cell. By 2020, the researchers in the U.S. and Europe have already achieved full transparency for the solar glass.

These transparent solar panels can be easily deployed in a variety of settings, ranging from skyscrapers with large windows to a mobile device such as a phone, a laptop, or an e-reader. As these solar power windows can simply replace the traditional glass windows in offices and homes, the technology holds the potential to virtually turn every building in the United States and the world into a solar producer.

How do solar panel windows work?

A transparent solar panel is essentially a counterintuitive idea because solar cells must absorb sunlight (photons) and convert them into power (electrons). When a solar glass is transparent, the sunlight will pass through the medium and defeat the purpose of utilizing sunlight. However, this new solar panel technology is changing the way solar cells absorb light.

The cell selectively harnesses a portion of the solar spectrum that is invisible to the naked eye, while allowing the normal visible light to pass through. To achieve this technological wonder, the researchers have developed the transparent luminescent solar concentrator (TLSC) rather than trying to do the impossible by creating a transparent photovoltaic glass cell.

Diagram: How Organic Salts in a Transparent Solar Panel Absorb Visible and In-Visible Light
The organic salts absorb UV and infrared, and emit infrared—processes that occur outside of the visible spectrum, so that it appears transparent. | Diagram: ExtremeTech

The TLSC is composed of organic salts that are designed to absorb specific invisible UV and infrared light wavelengths, which then glow (luminesce) as another invisible wavelength. This new wavelength is then guided to the edge of the window plastic, which thin PV solar cell strips convert it into electricity.

Once the mass production begins for transparent solar panels, researchers estimate that the TLSC should be able to deliver an efficiency of about 10%. This may not appear to be an earth-shattering number, but on a national or global scale, when almost every window in a home or office building consists of clear solar panels, the results can be transformative.

As the transparent solar panels cost comes down with their mass production and deployment, this non-intrusive technology can be scaled right from commercial and industrial applications to handheld consumer devices, while remaining very affordable.

Types of transparent solar panels

Just the way solar roof panels are currently produced using different technologies (Tesla’s solar shingles and other technologies), solar windows are also being developed using different techniques. The two major types of transparent solar panels include partial and full transparent panels.


Partially transparent solar panels

A German manufacturer, Heliatek Gmb, has developed this partially clear solar panel, which can absorb about 60 percent of the sunlight it receives. Compared to the conventional solar PV cells, the partially transparent solar panels have a lower efficiency at 7.2%. However, solar power generation can be increased by adjusting the balance between the sunlight that is transmitted and absorbed.

For instance, in south-facing glass buildings, it is often important to reduce the transmitted light (many such office buildings already use tinted glass). In these locations, the partially transparent solar panel can work very well.

Fully transparent solar panels

As described in the beginning of this report, researchers at MSU have already achieved a breakthrough to produce fully transparent photovoltaic glass panels that resemble regular glass. Researchers estimate the efficiency of these fully transparent solar panels to be as high as 10% once their commercial production commences.

It’s vital to understand here that when it comes to solar panel windows, efficiency of the panel is not the be all and end all. In practical terms, a less efficient solar window only means that the window has to be larger in size compared to the more efficient panel in order to generate the same amount of electricity.

Once fully transparent solar panels get integrated into large windows in buildings, their lower efficiency is bound to be overcompensated by their potential scale of deployment.

Solar panel blinds: An easy-to-implement solar window technology

Solar panel blinds are a supplement to transparent solar glass/panels when using the window to generate electricity. Solar power panels are designed to harvest sunlight to produce energy, while the essential function of window blinds is to block direct sun’s rays from entering inside.

Easy-To-Implement Solar Window: Solar Panel Blinds by SolarGaps
Photo: SolarGaps

Solar panel blinds are cleverly combining these two divergent functions. An innovative startup called SolarGaps has introduced solar panel blinds, which it claims can cut down energy costs by up to 70 percent. For every 10 sq. ft. of window space, these solar window blinds can generate 100 watts of power (you could roughly power three laptops with this much electricity).

These solar blinds can be installed either inside or outside, and you can control their angle and positioning using an app that will also inform you of the energy generation figures. It includes a setting to automatically optimize the angle of the blinds according to the position of the sun.

Pioneers in transparent solar panel research and manufacturing

Researchers at Michigan State University and MIT as well as manufacturers such as Ubiquitous Energy, Physee, and Brite Solar are pioneers in promoting this new solar panel technology.

Ubiquitous Energy

Ubiquitous Energy, in partnership with a leading glass manufacturer NSG Group, is developing Ubiquitous’s unique ClearView Power technology to integrate transparent solar panels into architectural glass windows. ClearView Power’s transparent solar coating can be directly applied to building windows at the time of the normal glass making process.


The technology also enhances energy efficiency of the buildings through blocking of infrared solar heat. When combined with solar energy generation through clear solar panels, it can lead to net-zero energy buildings. The company has already announced that ClearView Power’s transparent solar cells have reached an electricity conversion efficiency of 9.8%.

Physee

Physee is a European manufacturer that has introduced an advanced product called PowerWindow. In fact, it is the only currently installed transparent solar panel in the world right now (covering 300 sq. ft. in a Dutch bank building).

Physee’s PowerWindow makes use of small solar panels that are installed along the window pane edges to generate power. While these solar windows are unable to be a standalone power source for buildings yet, the company is confident of rapid improvements in the scale and efficiency of its transparent panels.

Physee Transparent Solar Windows Generating Electricity for the Building
Photo: Physee

PowerWindows serve as the building blocks for “SmartSkin,” the clear photovoltaic glass that the company is promoting as the “future-proof glass façade for next-generation sustainable buildings.” SmartSkin can work autonomously to sense, power, and regulate the climate inside the building using intelligent systems.

The future of transparent solar technology

The potential to generate renewable, clean energy from the sun is enormous with transparent solar panels, considering the number of skyscrapers and buildings already in existence or under construction with a massive amount of glass surface .

According to Richard Lunt, the Johansen Crosby Endowed Associate Professor of Chemical Engineering and Materials Science at MSU, highly transparent solar cells represent the “wave of the future” for new solar panel technologies.

Lunt says that these clear solar panels have a similar power-generation potential as rooftop solar, along with additional applications to improve the efficiency of buildings, cars and mobile devices. Lunt and his team estimate that the U.S. alone has about 5 to 7 billion square meters of glass surface at present. (Just in the last 10 years, as much as 682 million sq. ft. of office space has been added in the U.S.).

With this much of glass surface to cover, transparent solar panel technology has the potential to meet about 40 percent of the country’s annual energy demand. This potential is nearly the same as that of rooftop solar. When both these technologies are deployed complimentarily, it could help meet nearly 100 percent of the U.S. electricity needs if we also improve energy storage. comment


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