Future Solar Windows Will Provide Power with a View
Imagine how much you could save on electric bills if your home or office was able to generate its own power from the sunlight streaming through windows. Now that future may be possible thanks to photovoltaic cells being developed at MIT.
The best part is that you'll still be able to take in the view.
Using the window surfaces of existing buildings could provide much more surface area for solar power than traditional solar panels , said Vladimir Bulovi?, a researcher at MIT. In mornings and evenings, with the sun low in the sky, the sides of big-city buildings are brightly illuminated, he said, and that vertical "footprint" of potential light-harvesting area could produce a significant amount of power.
MIT's photovoltaic cells are based on organic molecules which harness the energy of infrared light while still allowing visible light to pass through them. If such material is used to coat a pane of standard window glass, it could provide power for lights and electronic devices.
Previous attempts to create transparent solar cells have either had extremely low efficiency (less than 1 percent of incoming solar radiation is converted to electricity), or have blocked too much light to be practical for use in windows.
But the MIT researchers were able to find a specific chemical formulation for their cells that, when combined with partially infrared-reflective coatings , gives both high visible-light transparency and much better efficiency than earlier versions comparable to that of non-transparent organic photovoltaic cells.
One of the most expensive aspects of traditional, thin-film solar-power system comes from installation costs that can range anywhere from half to two-thirds of the overall cost, and up to half of the cost of the panels themselves is for the glass and structural parts, Bulovi? said.
In a new building, adding the transparent solar cell material to the glass would be a relatively small incremental cost, since the cost of the glass, frames and installation would all be the same with or without the solar component, the researchers say.
For now, the work is still at a very early stage . But, Bulovi? and Richard Lunt, a postdoctoral researcher working on the project, expect that they should be able to reach 12 percent efficiency, making the photovoltaic cells comparable to existing commercial solar panels.
This will not be the ultimate solution to all the nation's energy needs, Bulovi? said, but rather it is part of "a family of solutions" for producing power without greenhouse-gas emissions. "It's attractive, because it can be added to things already being deployed," rather than requiring land and infrastructure for a whole new system, he said.
A paper by Bulovi? and Lunt describing their new system has been published online in the journal Applied Physics Letters, and will appear in a forthcoming issue of the print edition.
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