As we move away from fossil fuels like coal and gas as sources of energy, one of the better ways to produce power is by harvesting light from the sun. Solar panels are rapidly becoming cheaper and more efficient, and new solar farms are being built all around the world.
Most of our power is used in cities, but cities pose a unique problem for solar power. The buildings are too tall. Most of the sunlight hits the sides of buildings, where the windows are placed, instead of on the top where the solar panels might go.
We could replace windows with solar panels, but then we wouldn't have windows on our buildings, which isn't good. Instead, a group of researchers managed to build a window that also worked as a solar panel. Minute Earth explains:
At first, a solar panel window might seem like an oxymoron. After all, solar panels are supposed to absorb light while windows let it through. Windows and solar panels are basically polar opposites. And yet, using a unique trick of quantum mechanics the researchers managed to have their cake and eat it too.
The researchers built a pane of glass filled with quantum dots, which are tiny particles of silicon only a few nanometers in size. When sunlight hits these dots, they absorb it and emit more light at a different frequency. This light bounces around inside the glass until it hits the edge of the window, where it's absorbed by special solar panels placed around the window's edge.
Because the quantum dots are small and spread out, most of the light that hits the window passes through it, but enough gets redirected to the sides to generate some electricity. Right now, these solar windows aren't efficient enough to power more than a single cell phone, but with a few years of refinement solar windows might be worth it to actually install.
And once that happens, skyscrapers in cities around the world would have good reason to replace their normal windows with power-generating solar ones. In a few years, we might all be looking outside through solar panel glass.