• 11.18.13

Forget Solar Panels: This Sun-Powered Light Doesn’t Need Electricity

A simple coating to a building’s windows can redirect incoming sunlight to where it’s needed–say, on a ceiling for an ambient glow or to a desk fixture so you can get to work.

Forget Solar Panels: This Sun-Powered Light Doesn’t Need Electricity

Picture a dark, windowless office–the sort of depressing scene where telemarketers sit in cubicles or Peggy Olson first typed memos for Don Draper. Overhead, the fluorescent lights are probably blazing. But what if the same room suddenly had direct access to the sun? Totally different scene.


New technology from University of Cincinnati researchers could completely change how dark rooms are lit, whether they’re in office buildings or homes. The design, called the SmartLight, harnesses solar power, but not in the way you’d expect.

Right now, most sunlight hitting the side of a building is unused, or even unwanted, explains Anton Harfman, associate dean in University of Cincinnati’s College of Design, Architecture, Art, and Planning. “In many cases, sunlight’s a liability–if you have the corner office, it’s nice, but you often pull the blinds because of too much light. In the summer, you don’t want all of that extra heat in the building, so again, you pull the blinds, when other parts of the building are light-starved.”

Instead, the researchers developed a coating of tiny, fluid-filled cells that can be applied to windows on outside walls and to new interior windows. With a small electric pulse, the fluid in the cells changes shape so it can direct the light where it’s needed–to the ceiling for ambient lighting, to a special fixture to provide task lighting, or across the top of the room to “light-locked” areas.

“The ability to actually direct light where you want it and need it is profound,” says Anton Harfman, Associate Dean in the College of Design, Architecture, Art, and Planning at the University of Cincinnati, who is working on the project with Jason Heikenfeld, the researcher who originally created the technology. “It’s what architecture has always been about: it’s about light and how light enters a building. The implications for this technology would be pretty enormous, because if we can direct light from the perimeter of the building to an office, we don’t need artificially produced light.”

Extra light could also be stored as electricity, either sent back into the city grid or saved to power the building’s other needs. At night, the process could be done in reverse; a central room in the building could have a constellation of bright electric lights that send light back through the cells. On a cloudy day, natural sunlight and artificial light could be mixed.

All of this, the researchers say, could be controlled by a smartphone. Sitting at a desk, you could adjust lighting through an app that connects to the building’s server. While you could still have wall switches, they wouldn’t actually connect to wires, since the entire system is set up wirelessly; the light just beams through the air between windows.

Though the project is still at the early stages–the researchers have just proved that the cells can direct light at a small scale, and haven’t had the chance to test a larger system–they believe the technology can be built for a low cost. The coating is like an LCD screen, and the only other expense would be adding interior windows and a server.


Once it’s running, lighting bills–and the associated environmental costs–could basically be eliminated.

About the author

Adele Peters is a staff writer at Fast Company who focuses on solutions to some of the world's largest problems, from climate change to homelessness. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley.