Published on June 20th, 2014 | by James Ayre4
Solar Cell Efficiency Boosted As Much As 50% With New Optical Element
June 20th, 2014 by James Ayre
Solar cell efficiencies can be improved by as much as 50% with the use of a new optical element designed by engineers from the University of Utah, according to recent reports.
The “optical element” — which is essentially just a thin layer of transparent plastic or glass that can sort and concentrate light — can be readily integrated into the glass covering of a solar panel. As a result, the new “polychromat” appears to represent a fairly cheap means of boosting solar cell performance — though, as always, until the technology is commercialized, there are no certainties.
The researchers note that the technology could also be used to improve the power efficiency of cellphones, or to improve camera function in low light conditions.
“Currently, high-efficiency solar cells are very expensive because they have to be carefully manufactured in a complex environment and are only cost-effective for space or defense applications like the Mars Rover,” states Rajesh Menon, a Utah Science Technology and Research (USTAR) assistant professor of electrical and computer engineering at the U. “We have designed a very cheap optical element that can be incorporated into the cover glass of a solar panel that will separate sunlight into various colors.”
The University of Utah provides more:
The polychromat was 50 millimeters wide by 10 millimeters long, with 3 micrometer wide grooves to sort incoming light. The polychromat was made using photolithography for this study, but Menon says it can now be made cheaply by creating a mold of the polychromat and then stamping it out like a DVD.
The team placed the polychromat on top of a photovoltaic device, which is a device that generates a voltage when exposed to energy, especially light. The photovoltaic device is made of two absorber layers: gallium indium phosphide to absorb visible light, and gallium arsenide to absorb infrared light. When the University of Utah polychromat was added, the power efficiency increased by 16%.
“These colors can be absorbed by appropriate solar cells to increase the efficiency of the overall process without increasing the cost,” Menon explains.
Computer simulations were also performed that showed that a polychromat placed on a solar cell with eight different absorber layers possessed a theoretical efficiency of over 50%.
“With our approach, you can almost arbitrarily select the bands of light—within the laws of physics—to give more flexibility in the design of the panel,” states Menon. “With a normal lens it’s very difficult to actually separate the colors, and with a prism it’s difficult to get the separated light exactly where you want it.”
There are still challenges remaining, though, specifically with regard to incorporating the technology into production processes — the researchers think that, at the earliest, the technology could hit the solar market in 5-10 years.
Other applications could arrive earlier, though — “the polychromat concept could also be used to generate a brighter, more power-efficient LCD display in a cellphone, or to boost colors in a camera under low light conditions. These applications are being explored through Menon’s startup company, PointSpectrum Corporation.”
The new findings were just published in the journal Progress in Photovoltaics: Research and Applications.
In related news, an interesting new solar panel — one that’s relatively light and easy to install — just hit the market, coming to us via Giga Solar. Coinciding with the release of the “High Durability (D-Series) solar modules,” we had the opportunity to chat with the company’s Chief Business Development Officer, Sicco Westra. If you’re interested at all in solar panels, I recommend giving it a read.