Your Home's Windows Could Soon Generate Clean Energy

Semi-transparent solar cells are a game changer

  • Researchers in Australia have developed a special semi-transparent solar cell.
  • It’s slightly less efficient than traditional solar panels but lets in enough light to be used as a window.
  • The researchers want to install these semi-transparent electricity-generating windows in skyscrapers that usually lack roof space for traditional solar panels.
A concept of green energy showing trees reflected in the windows of tall buildings.

shomos uddin / Getty Images

Researchers have devised an innovative solution to turn urban eyesores into clean energy generators.

A team of Australian researchers has created semi-transparent solar cells which they fathom could one day allow skyscrapers to generate their own power. The transparent solar cells are made from perovskite cells, which are often hailed as the future of solar cells

“This work provides a major step forward towards realizing high efficiency and stable perovskite devices that can be deployed as solar windows to fulfill what is a largely untapped market opportunity,” Professor Jacek Jasieniak from the Department of Materials Science & Engineering at Monash University, said in a university press release.

Powered Windows

Crystalline silicon has been the go-to choice for building solar panels for decades. Researchers, however, have been looking for alternatives, primarily because of the costly and intensive process of creating silicon-based solar panels.

Perovskite solar cells have emerged as a promising alternative. Perovskite gets its name for its particular crystal structure. German scientist Gustav Rose discovered it in 1839. Perovskites are easy to synthesize, and their distinctive structure makes them highly efficient as photovoltaics (PV) for converting sunlight into power. 

Building on this, the team of researchers from ARC Centre of Excellence in Exciton Science led by Professor Jasieniak has created perovskite cells with a conversion efficiency of 15.5 percent, while allowing more than 20 percent of visible light through. To put this into perspective, rooftop silicon cells usually have an efficiency of about 20 percent.

In 2020, the same group of researchers produced semi-transparent perovskite solar cells with a 17 percent power conversion efficiency and could let 10 percent of visible light through. 

While the power-conversion efficiency in the latest research is a few notches lower than the team's previous results, the amount of visible light the new material allows to pass through has doubled. The researchers argue this would significantly increase their potential for use in a wide range of real-world applications.

"[Semi-transparent solar cells] have drawn significant attention in the building-integrated photovoltaic (BIPV) market, as they greatly increase the available surface area that can be used to generate electricity in an urban environment," note the researchers. "Furthermore, they also have the advantage of reducing incident heat gain into buildings by partially absorbing and reflecting sunlight."

One Step Closer

Another improvement in the perovskite solar cells created as part of the latest research is the long-term stability when tested for continuous illumination and heating, which the researchers fathom mimics the conditions the material would encounter in real-world use.

Buildings are not currently built to accommodate energy-generating facades.

"The underpinning science works, and the concept is fantastic, particularly for buildings with huge glass facades and relatively little roof space available for conventional silicon photovoltaics," Dr. James O'Shea, Associate Professor & Reader in Physics. School of Physics & Astronomy and University of Nottingham Energy Institute, told Lifewire in an email.

Lance Wheeler, a staff scientist at National Renewable Energy Laboratory (NREL), is also excited at the development. "The efficiency and transparency metrics of perovskite PV windows continue to rise and could lead to real-world impacts," Wheeler told Lifewire via email.

However, Wheeler pointed out that several areas need to be addressed in addition to efficiency and transparency before we see these semi-transparent PV windows deployed ubiquitously.

For starters, they'd need to take on an aesthetically acceptable color. Wheeler said Perovskite cells are yellow, orange, or red, and there should be an additional layer to change the color to neutral grays or subtle blues and greens, which are the most common for windows.

Wheeler also acknowledged that while perovskite materials have come a long way in terms of durability, building-integrated applications are even more demanding than rooftop or utility-scale solar since failure and replacement is more costly and disruptive to occupants. 

A tract of homes with solar panels on all the roofs.

Richard Newstead / Getty Images

Dr. O'Shea suggested perovskite solar cells can perhaps be used in tandem with traditional silicon to make hybrid cells with greater efficiency. He is confident the development of the solar windows will help drive the maturity of the perovskite solar cell technology, leading to their increased adoption in the coming years.

"Buildings are not currently built to accommodate energy-generating facades," pointed out Wheeler. "There needs to be education and change to the construction industry before this happens at a large scale."

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