Global solar installations are up 64% in the first half of 2025. There’s no denying it: More and more of the world is running on solar power.
And with that growth comes even more innovation.
In a new study, led by a research team at Nanjing University, scientists have created a transparent solar coating that turns ordinary windows into solar panels.
The researchers used a transparent, colorless, and one-directional solar concentrator that can easily and directly be applied to standard window glass. It’s made with a coating of “cholesteric liquid crystal,” a substance that has a unique ability to reflect wavelengths of light.
Then, the coating redirects sunlight toward photovoltaic cells on the edge of the windows.
“By engineering the structure of cholesteric liquid crystal films, we create a system that selectively diffracts circularly polarized light, guiding it into the glass waveguide at steep angles,” said Dr. Dewei Zhang, the co-first author on the study, in a statement.
“This allows up to 38.1% of incident green light energy to be collected at the edge.”
Some conventional “scattering-based” systems concentrate solar power by using large mirror surfaces to follow the daily movement of the sun.
This window coating, however, avoids the pitfalls of those systems, which include visual distortion, low efficiency, and poor scalability.
It maintains the clarity of a standard window — not a mirrored surface. The coating still lets in 64.2% of visible light through the window and maintains 91.3% color accuracy of a window without the coating applied.
Plus, it streamlines solar installation without the use of a clunky new solar module.
Experiments in the study showed that a typical 2-meter-wide window coated in the solar-capturing material could concentrate sunlight by 50 times. This, in turn, would reduce the number of photovoltaic cells required by up to 75%.
The result? Scalable and high-performance solar cells in infrastructure that already exists.
Scientists say the liquid crystal films can be scaled through roll-to-roll manufacturing, allowing them to be retrofitted onto existing windows. They also found that the design remains stable under long-term exposure, making this a feasible and lasting upgrade.
As the researchers continue to bring their invention to life, their future work will focus on enhancing the film’s efficiency, controlling how to guide the sunlight, and adapting the technology for greenhouses and transparent solar displays.
The ultimate goal is to turn passive glass into energy-generation surfaces across the globe.
“The CUSC design is a step forward in integrating solar technology into the built environment without sacrificing aesthetics,” Professor Wei Hu said in a statement.
“It represents a practical and scalable strategy for carbon reduction and energy self-sufficiency.”
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