Researchers in South Korea have developed a new method for creating solar windows that could solve one of the biggest problems with transparent solar cells: their reddish appearance. Scientists at Ulsan National Institute of Science and Technology discovered that by creating extremely tiny holes—about the size of a strand of hair—in crystalline silicon wafers, they could allow visible light to pass through while still generating electricity. When the holes are carefully spaced, they are nearly invisible to the naked eye, creating a neutral-colored, transparent surface.
The technology reached an efficiency of 12.2 percent, which researchers say is surprisingly high for a transparent solar cell. Unlike traditional solar panels, which can lose significant efficiency when positioned vertically because of the angle of sunlight, transparent solar cells are much less affected when installed as windows. The team believes efficiency could eventually reach 15 percent, while researcher Lance Wheeler of the National Renewable Energy Laboratory suggested the technology could potentially reach around 18 percent with further development.
The idea could be especially valuable for skyscrapers, which have enormous amounts of window space but limited rooftop area for conventional solar panels. Instead of simply letting sunlight pass through windows, buildings could potentially turn their glass façades into electricity-generating surfaces. Researchers also believe similar technology could eventually be used in electric vehicles, smartphones and other devices, allowing surfaces that were previously passive to help generate power.
Transparent solar technology has been explored before, including research that produced completely transparent solar glass using organic photovoltaic materials. However, some earlier approaches achieved much lower efficiency. The South Korean team’s use of crystalline silicon could represent a different path toward practical solar windows. While the technology is still being developed, researchers believe it could eventually transform ordinary glass into a largely invisible source of renewable energy.