Over the years, we’ve written a number of stories about the potential of solar windows that could convert light into energy. The technology, however, has yet to take off.

The main problem is that the solar windows created thus far have been too opaque, failing to allow much light to come through the windows. In search of a solution, scientists at South Korea’s Incheon National University have developed a solar panel that uses transparent photovoltaic technology (TPV). Unlike conventional solar panels, TPV can harness the invisible UV spectrum of sunlight to create energy, rather than the visible light harvested by opaque panels.

The transparent solar windows use titanium dioxide and nickel oxide as semiconductors. The benefit of titanium oxide is that it’s non-toxic and eco-friendly, while nickel oxide is abundant. In tests so far, these solar panels have an efficiency of 2.1 percent, which is quite a bit less than the 8 percent efficiency rate of semi-transparent windows we wrote about back in August. 

However, Incheon’s transparent windows do allow a lot more light to pass through—and considering the impressive track record of innovation within solar technology, we can reasonably expect these transparent windows to become more efficient over the years.

“While this innovative solar cell is still very much in its infancy, our results strongly suggest that further improvement is possible for transparent photovoltaics by optimizing the cell’s optical and electrical properties,” said Joondong Kim, who led the research team.