Tag Archives: Solar Cells

Stanford’s Thinner Than The Wavelength of Sound Solar Cells

One thing we know about solar cells is that thinner it is less expensive it gets; thin film solar is cheaper than the standard silicon cells. Stanford University’s team of Researchers has come up with Solar cells thinner than the wavelengths of light which are also more efficient! They say Ultra-thin solar cells can absorb sunlight more efficiently than the thicker, more expensive-to-make silicon cells used today, because light behaves differently at scales around a nanometer (a billionth of a meter).

The team consists of Shanhui Fan, associate professor of Electrical engineering and postdoctoral researcher Zongfu Yu who is the lead on the PNAS paper. Aaswath Raman, a graduate student in applied physics, also worked on the research and is a coauthor of the paper.

Everyone worked with the assumption that light travels in a straight line i.e. if a ray of light hits a mirror it bounces back as another ray. When Yu began investigating the behavior of light inside a material of deep subwavelength-scale – substantially smaller than the wavelength of the light – that it became evident to him that light could be confined for a longer time, increasing energy absorption beyond the conventional limit at the macroscale. On further research Yu figured out that he could increase absorption rate by 12% by sandwiching the organic thin film between two layers of material – called “cladding” layers – that acted as confining layers once the light passed through the upper one into the thin film. Atop the upper cladding layer, he placed a patterned rough-surfaced layer designed to send the incoming light off in different directions as it entered the thin film.

The project was supported by funding from the King Abdullah University of Science and Technology, which supports the Center for Advanced Molecular Photovoltaics at Stanford, and by the U.S. Department of Energy.

Source – The Stanford News

Solar Impulse: The “Utopian” Flight of Fancy Realized!

According to the American Poet and Novelist James Dickey “Flight is the only truly new sensation than men have achieved in modern history” and I tend to agree.

Flight in itself helped humankind shorten the distances across the oceans and gave wings to mans imagination, it also helped man reach the moon and beyond. Like Bill Gates said The Wright Brothers created the single greatest cultural force since the invention of writing.  The airplane became the first World Wide Web, bringing people, languages, ideas, and values together”. It has been 100 plus years since the first flight by the Wright brothers and the planes have gone from biplane gliders to supersonic jets and beyond. Until now the faster plane did not mean it was focusing on fuel efficiency, mostly longer flights meant larger engines and higher fuel capacity. In today’s move towards a greener energy solution and a lower carbon footprint it looked as though the flights were one of the things which we would be still running on oil however pricey it got.

I called it a flight of fancy not to trivialize it, but to say how unbelievably awestruck I am! The 20th century has had its share of amazing discoveries from the first flight to the moon landing, conquering the Everest and the Poles, circum navigating the earth faster than the previously estimated etc… It was also the century when humankind adversely effected the environment most and created the need for alternative energy sources a priority for the survival and sustenance of our planet.

On the 7th of June 2010 something spectacular happened, which helped take the journey in the skies to the next level- A flight powered purely by the Sun- Solar Impulse!!

The Brains behind the Solar Impulse Piccard and Borschberg Pictures from Solar Impulse

The team led by two pilots- innovators & visionaries: Bertrand Piccard, psychiatrist and aeronaut, who made the first non-stop round-the-world balloon flight, is the initiator and chairman AND André Borschberg, an engineer and graduate in management science, a fighter pilot and a professional airplane and helicopter pilot, as the CEO started their journey towards creating The Solar Impulse in 2003 and announced it in the May of 2007. The former’s avant-garde vision and the latter’s entrepreneurial and managerial experience are an ideal combination. The idea at the heart of the Solar Impulse project is to get closer to perpetual flight in a machine powered only by solar energy. This challenge necessitated the use of technology unique to this type of aircraft, such as that linked with the gathering of energy via photovoltaic cells and storing it in batteries for use in powering the engines at night.

On the morning of 07/07/2010 at 6.51 AM in Switzerland André Borscherg CEO and co-founder of the Solar impulse project took to the skies in the Solar Impulse HB-SIA from the Payerne Airbase. The flight was powered by 12,000 solar panels built into its enormous 63.4meter wing, which charged its 400kg of batteries during the long ascent. The flight successfully completed its aim of 24 hours in the flight using nothing but solar power and landed back in the Payerne Airbase after 26 hours and 9 minutes having successfully completed its mission. The organizers said the flight was the longest and highest by a piloted solar-powered craft, reaching an altitude of just over 28,000 feet above sea level at an average speed of 23 knots, or about 26 miles per hour.

After the flight landed successfully André Borschberg said from the cockpit of the Solar Impulse “During the whole of the flight, I just sat there and watched the battery charge level rise and rise! Sitting in a plane producing more energy than it consumes is a fantastic feeling”.

Bertrand Piccard added “This is a highly symbolic moment: flying by night using solely solar power is a stunning manifestation of the potential that clean technologies offer today to reduce the dependency of our society on fossil fuels!”.

The Associated Press quoted Dr. Piccard as saying “When you took off, it was another era. You land in a new era where people understand that with renewable energy you can do impossible things.”

The project’s designers had set out to prove that — theoretically at least — the plane, with its airliner-size, 208-foot wingspan, could stay aloft indefinitely, recharging batteries during the day and using the stored power overnight. “We are on the verge of the perpetual flight,” Dr. Piccard said.

“The airplane is the means of transport using the most energy and it alone represents more than 3 % of the total gas emissions contributing to the greenhouse effect on the planet! As an aerial photographer I know something about this. If all airplanes were to become solar, this would be tremendous. And Piccard is a dreamer: I know of nothing more extraordinary than helping people realise their dreams.”-Yann-Arthus Bertrand

There might or might not come a time when a 300 passenger plane flies on solar power alone. In the mean while even as a single person flight it gives us hope that a greener option is possible. And like the Solar impulse website says “if we do not invest in the scientific means to develop new energy sources, we shall find ourselves in a major crisis, which will prevent us from handing over the planet to the next generation.”


You can read more about the Solar Impulse on its website HERE

Pictures source Solar Impulse.com

Find the Article on Solar Impulse flight in the NY times here