A 16 cm² Photovoltaic Module Achieves 15.8% Conversion Efficiency with an Average Visible Transmittance of 20%
Recent Advances in Transparent Solar Panels
The latest advancement in transparent solar panels comes from South Korea, specifically from the Ulsan National Institute of Science & Technology (UNIST). A team of scientists from the School of Energy and Chemical Engineering has developed a new type of transparent, neutral-colored silicon solar cell that promises to become a key technology for tomorrow’s energy industry.
The mini photovoltaic module created from this cell has achieved a conversion efficiency of 15.8% while allowing 20% of incident light to pass through.
Transparent Solar Cells: What They Are and How They Work
Transparent solar cells are photovoltaic devices that merge the benefits of visible transparency with the ability to convert light into electricity. Primarily based on organic materials, dyes, and perovskites, these cells are emerging as potential elements for integrated power generation in buildings, vehicles, or mobile devices. While promising, the concept traditionally required a trade-off between photovoltaic efficiency and visible transparency. In other words, the more transparent the cell, the lower the energy production.
Significant advancements in this field have also been achieved thanks to UNIST’s work on crystalline silicon (c-Si), the top photovoltaic material, though inherently opaque.
Thin-film c-Si has long been seen as a method to increase device transparency because the amount of light transmitted through a material is generally inversely proportional to its thickness. However, a drawback of this approach is that thin silicon films tend to take on a reddish tint.
In 2020, researchers at UNIST, led by Professor Kwanyong Seo, pursued an alternative method to achieve “neutral” transparency. They applied a special microstructure with tiny holes—essentially light-transmission windows—onto a 200 μm thick c-Si wafer. This innovative design produced a unique aesthetic result and exceeded 12% efficiency.
From Cell to Transparent Solar Panel
Since then, research on transparent photovoltaic panels has accelerated, exploring various approaches and combining different materials. However, one of the biggest challenges has remained scaling the cell into modules.
This is where UNIST’s new study, led by Professor Kwanyong Seo, comes into play. “Transparent solar cells have substantial potential as continuous energy generators, allowing their use in situations where conventional devices might not be feasible,” the publication in PNAS states. “However, research aimed at modularizing transparent cells to regulate the overall voltage and current they produce – a crucial step towards practical application – is still in its early stages.”
The team achieved a high-efficiency transparent solar panel, colorless and as transparent as glass, by introducing a “full back-contact” design. In other words, all components of the cell—crystalline silicon units—were placed on the back.
How Efficient Are Transparent Solar Panels?
The result? A 16 cm² transparent photovoltaic panel capable of converting 15.8% of incident light into electricity, with a visible transmittance of 20%. The mini-module successfully charged a smartphone using natural sunlight and also demonstrated the potential for using the screen of a small mobile device as an energy source.
“This study fundamentally addressed the aesthetic issue of the current method of modularizing solar cells through the design of the new device structure,” researchers Jeonghwan Park and Research Associate Professor Kangmin Lee stated. “It has shown the potential for transparent silicon solar cells to be used in various fields, such as small devices, buildings, and automotive glass.“
