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A piece of clear glass, left, is compared to a transparent solar cell, right, developed by UCLA professor Yang Yang and his team. (Courtesy of UCLA / July 24, 2012) |
By Deborah Netburn
July 24, 2012, 12:50 p.m.
In the future, solar panels will no longer be restricted to the roof. You'll be able to put them on your windows too.
Scientists at UCLA have invented a thin, transparent solar cell that can turn the energy of the sun into electricity, while still allowing visible light to stream through it.
"If you take a piece of glass and compare it to our solar cell, it is difficult to tell the difference," said study leader Yang Yang, a professor at UCLA and director of the Nano Renewable Energy Center at California NanoSystems Institute (CNSI).
The transparent solar cell is made out of a plastic that absorbs invisible infared light while letting most visible light pass through.
Additionally, even the metal that carries the charge out of the cell is transparent. In collaboration with Paul S. Weiss, director of CNSI, Yang was able to install a silver nano wire that served as the conductive metal that is essentially invisible.
The result? A solar panel that is 70% transparent to the human eye.
There is a catch, of course: Transparent solar cells are not nearly as efficient as opaque ones. Yang said that by solving the visibility problem, 30% of a cell's energy-absorbing capability had to be sacrificed.
The good news is that the process is very economical, and the material can be fabricated as a liquid that can be sprayed on a surface, much in the same way that car factories spray paint onto automobiles.Yang said he had already received calls from people ready to buy the transparent solar cells, but he does not expect the product to be ready for commercial use for at least five years.
"I don't have the patience to wait much longer," he said. "I'd like to say in five years we'll have something on a small scale, and then in 10 years it will be popular."
Photovoltaics
Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect.
Photovoltaic power generation employs solar panels composed of a number of solar cells containing a photovoltaic material.
Materials presently used for photovoltaics include monocrystalline silicon, polycrystalline silicon, amorphous silicon,cadmium telluride, and copper indium gallium selenide/sulfide.
Due to the growing demand for renewable energy sources, the manufacturing of solar cells and photovoltaic arrays has advanced considerably in recent years.
Solar photovoltaics is growing rapidly, albeit from a small base, to a total global capacity of 69 GW at the end of 2011.
The total power output of the world’s PV capacity run over a calendar year is equal to some 80 billion kWh of electricity.
This is sufficient to cover the annual power supply needs of over 20 million households in the world.
Solar photovoltaics is now, after hydro and wind power, the third most important renewable energy source in terms of globally installed capacity.
More than 100 countries use solar PV. Installations may be ground-mounted (and sometimes integrated with farming and grazing) or built into the roof or walls of a building (either building-integrated photovoltaicsor simply rooftop).
Driven by advances in technology and increases in manufacturing scale and sophistication, the cost of photovoltaics has declined steadily since the first solar cells were manufactured and the levelised cost of electricity (LCOE) from PV is competitive with conventional electricity sources in an expanding list of geographic regions.
Net metering and financial incentives, such as preferential feed-in tariffs for solar-generated electricity, have supported solar PV installations in many countries.
With current technology, photovoltaics recoup the energy needed to manufacture them in 1 to 4 years.
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