Imagine windows that not only provide a clear view and illuminate rooms, but also use sunlight to efficiently help power the building… MUMBAI MIRROR BUREAU
Engineers at the Massachusetts Institute of Technology (MIT) in the US report a new approach to harnessing the sun’s energy: Colourful window panes that double up as energy generators. Their work – published in Friday’s issue of Science – involves the creation of what they call a ‘solar concentrator.’
“Using our technology, light is collected over a large area like a window and then, gathered or concentrated at the edges,” explains Marc Baldo, leader of the work and Associate Professor of Electrical Engineering.
So, rather than covering a roof with expensive solar cells – the semiconductor devices that transform sunlight into electricity – the cells only need to be around the edges of a flat glass panel. In addition, the focused light increases the electrical power obtained from each solar cell “by a factor of over 40”, Baldo says.
INCREASED EFFICIENCY
Because the system is simple to manufacture, the team believes that it could be implemented within three years – even added onto existing solar-panel systems to increase their efficiency by 50 per cent for minimal additional cost. That, in turn, would substantially reduce the cost of solar electricity.
In addition to Baldo, the researchers involved are Michael Currie, Jon Mapel, and Timothy Heidel, all graduate students in the Department of Electrical Engineering and Computer Science, and Shalom Goffri, a postdoctoral associate in MIT’s Research Laboratory of Electronics.
“Professor Baldo’s project utilises innovative design to achieve superior solar conversion,” says Dr Aravinda Kini, program manager in the Office of Basic Energy Sciences in the US Department of Energy’s Office of Science, a sponsor of the work. “This accomplishment demonstrates a revolutionary advance in solar energy utilisation in a cost-effective manner.”
Solar concentrators in use today “track the sun to generate high optical intensities, often by using large mobile mirrors that are expensive to deploy and maintain,” Baldo and colleagues wrote. Further, “solar cells at the focal point of the mirrors must be cooled, and the entire assembly wastes space around the perimeter to avoid shadowing neighbouring concentrators”.
The MIT solar concentrator involves a mixture of two or more dyes that is essentially painted onto a pane of glass or plastic. The dyes work together to absorb light across a range of wavelengths, which is then re-emitted at a different wavelength and transported across the pane to waiting solar cells at the edges.
THAT ’70S TECHNOLOGY
In the 1970s, similar solar concentrators were developed by impregnating dyes in plastic. But the idea was abandoned because, among other things, not enough of the collected light could reach the edges of the concentrator. Much of it was lost en route.
The MIT engineers realised that perhaps those same advances could be applied to solar concentrators. The result? A mixture of dyes in specific ratios, applied only to the surface of the glass that allows some level of control over light absorption and emission.
“We made it so the light can travel a much longer distance,” Mapel says. “We were able to substantially reduce light transport losses, resulting in a ten-fold increase in the amount of power converted by the solar cells.”
Mapel, Currie and Goffri are starting a firm, Covalent Solar, to commercialise the technology.
MUMBAI MIRROR BUREAU
Engineers at the Massachusetts Institute of Technology (MIT) in the US report a new approach to harnessing the sun’s energy: Colourful window panes that double up as energy generators. Their work – published in Friday’s issue of Science – involves the creation of what they call a ‘solar concentrator.’“Using our technology, light is collected over a large area like a window and then, gathered or concentrated at the edges,” explains Marc Baldo, leader of the work and Associate Professor of Electrical Engineering.
So, rather than covering a roof with expensive solar cells – the semiconductor devices that transform sunlight into electricity – the cells only need to be around the edges of a flat glass panel. In addition, the focused light increases the electrical power obtained from each solar cell “by a factor of over 40”, Baldo says.
INCREASED EFFICIENCY
Because the system is simple to manufacture, the team believes that it could be implemented within three years – even added onto existing solar-panel systems to increase their efficiency by 50 per cent for minimal additional cost. That, in turn, would substantially reduce the cost of solar electricity.
In addition to Baldo, the researchers involved are Michael Currie, Jon Mapel, and Timothy Heidel, all graduate students in the Department of Electrical Engineering and Computer Science, and Shalom Goffri, a postdoctoral associate in MIT’s Research Laboratory of Electronics.
“Professor Baldo’s project utilises innovative design to achieve superior solar conversion,” says Dr Aravinda Kini, program manager in the Office of Basic Energy Sciences in the US Department of Energy’s Office of Science, a sponsor of the work. “This accomplishment demonstrates a revolutionary advance in solar energy utilisation in a cost-effective manner.”
Solar concentrators in use today “track the sun to generate high optical intensities, often by using large mobile mirrors that are expensive to deploy and maintain,” Baldo and colleagues wrote. Further, “solar cells at the focal point of the mirrors must be cooled, and the entire assembly wastes space around the perimeter to avoid shadowing neighbouring concentrators”.
The MIT solar concentrator involves a mixture of two or more dyes that is essentially painted onto a pane of glass or plastic. The dyes work together to absorb light across a range of wavelengths, which is then re-emitted at a different wavelength and transported across the pane to waiting solar cells at the edges.
THAT ’70S TECHNOLOGY
In the 1970s, similar solar concentrators were developed by impregnating dyes in plastic. But the idea was abandoned because, among other things, not enough of the collected light could reach the edges of the concentrator. Much of it was lost en route.
The MIT engineers realised that perhaps those same advances could be applied to solar concentrators. The result? A mixture of dyes in specific ratios, applied only to the surface of the glass that allows some level of control over light absorption and emission.
“We made it so the light can travel a much longer distance,” Mapel says. “We were able to substantially reduce light transport losses, resulting in a ten-fold increase in the amount of power converted by the solar cells.”
Mapel, Currie and Goffri are starting a firm, Covalent Solar, to commercialise the technology.
Researchers Marc Baldo (left) and Shalom Goffri hold examples of the low-cost organic solar concentrators that collect and focus different colours of sunlight. Stacking multiple concentrators optimises the overall power output
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