Advance in solar power technology

[glatt]

This news is a week old, but I just saw it. A team at Princeton has developed a new kind of solar cell and dramatically increased its efficiency. This new cell uses nanotechnology to be almost 3 times more efficient than the best cells out there today.

Chou, the Joseph C. Elgin Professor of Engineering, said the research team used nanotechnology to overcome two primary challenges that cause solar cells to lose energy: light reflecting from the cell, and the inability to fully capture light that enters the cell.

With their new metallic sandwich, the researchers were able to address both problems. The sandwich — called a subwavelength plasmonic cavity — has an extraordinary ability to dampen reflection and trap light. The new technique allowed Chou's team to create a solar cell that only reflects about 4 percent of light and absorbs as much as 96 percent. It demonstrates 52 percent higher efficiency in converting light to electrical energy than a conventional solar cell.

That is for direct sunlight. The structure achieves even more efficiency for light that strikes the solar cell at large angles, which occurs on cloudy days or when the cell is not directly facing the sun. By capturing these angled rays, the new structure boosts efficiency by an additional 81 percent, leading to the 175 percent total increase. Chou said the system is ready for commercial use although, as with any new product, there will be a transition period in moving from the lab to mass production.

In a nutshell, there is a tiny mesh on the top surface of the cell, and light waves can get through the holes in the mesh, but can't bounce back out because the holes are too small. So they get trapped inside and generate electricity.

The conventional cell reflects a ton of light, but the new cell traps it. These new cells look pitch black and work well even on cloudy days.

Electron microscope view of the mesh on the surface of the cell.


Nanotechnology sounds expensive to manufacture, but solar cells are already expensive to manufacture, so maybe these new cells can compete on price too. I hope so.

[Spexxvet]

Cool. Hopefully the technology develops quickly

[BigV]

Another advance:

http://www.greentechmedia.com/articl...d-solar-savant

http://www.fastcoexist.com/1678871/a...ost-efficiency

There are two interesting ideas here, one having to do with solar power and one having to do with money.

Money first. Peter Thiel, creator of PayPal and an early FaceBook investor has beaucoup money, of course, and he has a plan to let young people with great ideas unleash their creativity free from the bounds of a class schedule and a work schedule. He offers 20 kids under 20 years old $100,000 to fund their businesses. The catch? They have to drop out of college so they can focus on their business ideas. Very bold!

The second item is the idea/product of one of these Thiel Fellows, Eva Full. She's developed a way to retrofit existing solar panels to track the sun. This isn't a new idea, but her's is a passive system, requiring no motors or extra load on the panel. She uses bi-metal brackets whose differential expansion rates can exert a force thereby changing the angle of the panel, all by the direct influence of the sun's energy.

[jimhelm]

wow. like flowers.

have you noticed how inexpensive and prevalent flat panel tv monitors have become in the last 3 years? THey even have tv at the gas pump!..... I bought a 46" tv for $348. that's retarded. They must just be cranking out flat panels at unbelievable rates. Let's hope they can do that with these solar panels. cover every roof with them.

[Lola Bunny]

RE: solar power technology -- that is great!

[tw]

Reflection is not the major reason for low solar cell efficiencies. Semiconductors only create electricity from photons at specific frequencies. Other frequencies get reflected or lost as heat.

Meanwhile, a new material called dilute nitrates were developed for better fiber optic communication about a decade ago. Recently, Solar Junction implemented this in a solar cell that claims a phenomenal 44% efficiency. By using multiple PN junctions tuned to significant frequencies of light. A lab version has three junctions. Speculation says efficiencies of 50% may be possible with four or six junctions.

Required in any recommendation are numbers. No numbers is the first fact to see through a myth. How efficient was that Princeton cell? I did not see any numbers. Maybe numbers exist. But I read looking for what is most important - numbers. Those numbers should even be in every executive summary.

A recommendation without numbers should have had everyone asking damning questions. Not asking that question in 2003 meant a majority also believed Saddam had WMDs. A contempt for the American soldier. If a miracle device does not include numbers, then it may be as bogus as Listerine or Pond's Age Defying Creams.

Solar Junction addressed a primary reason for low efficiency solar cells. Not reflection. Solar Junction also quantified those claims with specific numbers. Photocells, unfortunately, were not tuned to the many frequencies found in sunlight. Which explains so many solar cells with as low as 2% efficiency.

[ZenGum]

The original article includes a link to the peer-reviewed article, at http://www.opticsinfobase.org/oe/abs...=oe-21-101-A60

It has the numbers, but they are a bit disappointing.

Experimentally, the PlaCSH-SCs have achieved (1) light coupling-efficiency/absorptance as high as 96% (average 90%), broad-band, and Omni acceptance (light coupling nearly independent of both light incident angle and polarization); (2) an external quantum efficiency of 69% for only 27% single-pass active layer absorptance; leading to (3) a 4.4% power conversion efficiency (PCE) at standard-solar-irradiation, which is 52% higher than the reference ITO-SC (identical structure and fabrication to PlaCSH-SC except MESH replaced by ITO), and also is among the highest PCE for the material system that was achievable previously only by using thick active materials and/or optimized polymer compositions and treatments. In harvesting scattered light, the Omni acceptance can increase PCE by additional 81% over ITO-SC, leading to a total 175% increase (i.e. 8% PCE).

Working backwards from the final result, it seems the regular cells turned maybe 3% of the sunlight into electricity. All those claims of huge percentage increases are starting from a very low base. They've tweaked this up to 8 %.

That 44% efficiency you mentioned - is that the percentage of solar energy that ends up as electricty (i.e. PCE)? or the percentage of photons which, having reached the absorbtion area, get picked up by the system? There could be a big difference. We must make sure we're comparing apples and apples, not apples and apple juice.

[tw]

Originally Posted by ZenGum

That 44% efficiency you mentioned - is that the percentage of solar energy that ends up as electricty (i.e. PCE)? or the percentage of photons which, having reached the absorbtion area, get picked up by the system?

They discuss total efficiency of light to electricity. But do not detail where that incoming photon energy is measured (before entry, inside the semiconductor material, etc). The subtitle in IEEE Spectrum says

Silicon Valley start-up Solar Junction has raised the bar for solar efficiency to 44 percent, and even higher values are in the cards. The company has a road map for reaching 50% efficiency and beyond.

ZenGum is asking the right questions.

Does that mean we can expect solar cells to be that efficient in the next decade? Maybe not. The article remains vague about what might compromise the technology. Too much positive spin usually means an author did not ask damning questions. Maybe a business school graduate or communication major.

Maybe one in ten innovations defined by numbers actually make it. Products recommended without numbers have a near zero success rate.

I waited to reply here. To see how many would reach a conclusion or excitement when numbers for the Princeton cell were obviously missing or misleading.

The "News at Princeton" article referred to 81% and 175% improvement. Why do we always demand numbers? Those numbers never mentioned "improvement over what" (as ZenGum notes). Since they did not say improvement over what, then the author may have been a business school graduate or something just as naive.

Those who demanded numbers in 2003 saw that Saddam could not have WMDs. Numbers (mostly lack of them) exposed George Jr's administration as liars. Read posts back then to appreciate how few in 2003 were demanding numbers. How many knew only from subjective claims. Numbers identified a WMD myth before Mission Accomplished even started.

We may see products based in Solar Junction's innovation. But with numbers provided (by ZenGum) from those other citations, the Princeton solar cell is virtually zero improvement.

Another innovation in 2000 was a Foveon chip. That promised to fix a compromise in CCD or CMOS based cameras. One chip detected all three colors. Current technology only had black and white sensors each covered in a color filter for each primary color. Three sensors per pixel. And complex computer algorithms to adjust for variations in each sensor.

Foveon chip was even demonstrated and was to be marketed in a Sigma Designs camera. Innovation that actually works and is defined superior by numbers has maybe a one in ten chance of succeeding. The Foveon chip (that performs similar to that Solar Junction chip) did not succeed.

Most advanced solar cells, such as those on the Martian Rovers Spirit and Oppurtunity must be over 10% efficient. Best we could do. Curiousity, instead, uses a nuclear battery. Best solar cells possible when Curiousity was recently launched are still too inefficient.

Moving on to innovation. Quantum dots are expected to achieve a 60% efficiency. Numbers that suggest a promising success rate - maybe better than one in ten chance of succeeding. Innovation is that difficult. And now made harder since the Republican party is openingly subverting science and innovation (such as Quantum physics). But any promise that does not include numbers is best called a scam.

A point made obvious by the "News at Princeton" article. And how to identify so many news reports from Fox News as propaganda for the naive. The naive are told how to think without "reasons why" and numbers. A point that applies to more than just science. And so the question.

Did each reader see obvious problems with the Princeton cell? It was a perfect example of spin. To an educated layman, it was not promising. Essential and missing numbers were a first indication.

But then so many are so easily scammed as to believe in Listerine and Pond's "Age Defying Creams". Even numbers (or lack of them) make a scam obvious to a layman. Above examples recited here to demonstrate.

[ShannonBush]

Originally Posted by glatt

, but I just saw it. A team at Princeton has developed a new kind of solar cell and dramatically increased its efficiency. This new cell uses nanotechnology to be almost 3 times more efficient than the best cells out there today.



In a nutshell, there is a tiny mesh on the top surface of the cell, and light waves can get through the holes in the mesh, but can't bounce back out because the holes are too small. So they get trapped inside and generate electricity.
Attachment 42173
The conventional cell reflects a ton of light, but the new cell traps it. These new cells look pitch black and work well even on cloudy days.

Electron microscope view of the mesh on the surface of the cell.
Attachment 42174

Nanotechnology sounds expensive to manufacture, but solar cells are already expensive to manufacture, so maybe these new cells can compete on price too. I hope so.

Solar technology has come long way in recent time but still there is lot to do to improve efficiency.. I have got solar panels and i am not able to get the desired electricity output

[glatt]

What's your solar panel setup? Roof based? How much current do they provide during full exposure? Where are you located?

[BigV]

oh, and by the way, welcome to the cellar ShannonBush!