Researchers in South Korea have developed an innovative approach to creating transparent solar windows using crystalline silicon, one of the most widely used materials in solar panels.

The team, led by researchers at the Ulsan National Institute of Science and Technology (UNIST), found that they could make silicon wafers partially transparent by creating extremely tiny holes throughout the material. The openings are so small and carefully arranged that they are virtually invisible to the naked eye.

The breakthrough could help solve a major challenge facing transparent solar technology: many existing solar windows have a noticeable colored tint, often reddish or brownish. The researchers’ design allows visible light to pass through the silicon while maintaining a more natural, neutral appearance.

The researchers published their findings in the journal Joule. Their prototype achieved a power-conversion efficiency of 12.2%, an impressive result for a transparent solar cell.

Traditional solar panels can lose some efficiency when installed vertically because of the changing angle of sunlight. Transparent solar cells, however, can be particularly useful on windows because they can continue producing electricity efficiently even when mounted vertically.

According to the researchers, the technology could eventually reach around 15% efficiency, while other experts believe further development could potentially push it closer to 18%.

The concept works by carefully balancing two functions within the silicon wafer. Tiny microholes allow sunlight to pass through, creating transparency, while other sections of the wafer remain active and absorb sunlight to generate electricity.

The researchers believe this could open the door to a new generation of colorless, transparent photovoltaic technology.

Solar windows could be especially valuable for high-rise buildings, which often have enormous areas of glass but limited roof space for conventional solar panels. Instead of simply letting sunlight enter a building, windows could also turn part of that sunlight into electricity.

The technology could potentially have applications beyond buildings as well. Transparent solar materials could one day be incorporated into vehicle windows, electric cars, electronic devices, and other surfaces exposed to sunlight.

Transparent photovoltaics have been explored before. Previous research has produced see-through solar glass using thin organic photovoltaic films, but those systems generally achieved lower efficiencies. The new silicon-based approach demonstrates that transparency and relatively high energy production can potentially be combined.

The researchers’ work represents a promising step toward turning everyday glass surfaces into sources of renewable energy—without significantly changing the appearance of the windows.

If the technology can be successfully scaled for commercial use, future buildings could generate electricity not only from their roofs, but from their windows as well.