JAN 27

If you've bought a solar panel, you want every photon that lands on it to work towards generating electricity. The more photons you absorb, the more electricity you generate. But, at present, a typical silicon solar cell only absorbs about two-thirds of the sunlight that strikes it, while the remaining third is reflected.

Shawn-Yu Lin, a professor of physics at Rensselaer Polytechnic Institute, has developed an anti-reflective coating (actually seven layers of coating) that raise the absorption of a solar panel to almost 100 percent. A typical silicon solar cell with this anti-reflective coating will absorb 96.21 percent of the sunlight that strikes it, and less than 4% of the light is reflected.

Typical antireflective coatings are engineered to transmit light of one particular wavelength. Lin’s new coating stacks seven of these layers, one on top of the other, in such a way that each layer enhances the antireflective properties of the layer below it. These additional layers also help to “bend” the flow of sunlight to an angle that augments the coating’s antireflective properties. This means that each layer not only transmits sunlight, it also helps to capture any light that may have otherwise been reflected off of the layers below it.

Not only does this coating significantly improve the overall efficiency of the panel, but it also offsets the need for panel orientation and tracking hardware. Reflection tends to increase as the angle of the sun moves farther from perpendicular to the panel, which is one of the reasons many solar panels are mounted on tracking equipment. But this coating is effective regardless of the angle of the light striking it.

This means that a stationary solar panel treated with the coating would absorb 96.21 percent of sunlight no matter the position of the sun in the sky. So along with significantly better absorption of sunlight, Lin’s discovery could also enable a new generation of stationary, more cost-efficient solar arrays.

This means that many smaller fixed installations of solar panels would be more efficient, and without as much need for additional (and costly) tracking hardware. (Tracking hardware still keeps a wider area of light falling on the solar panel, so its usefulness is not completely undone by this development.)

The remaining questions are how expensive it will be to commercialize this process, and how expensive the panels themselves will be, compared to ordinary, uncoated panels. Simpler, fixed solar collectors will be less expensive to buy and easier to maintain than installations that need tracking hardware. Homeowners, especially, whose roofs may not be ideally oriented for solar collection, should be interested in panels with this coating, since it will provide the greatest benefit in more marginal installation locations.

link: Rensselaer Polytechnic Institute News

via: Device Daily

Comments (11)

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Interesting Advancement
written by Royce Fullerton, January 27, 2009

This sounds like a great step in anti-reflection coating technology. But as with most advancements in solar cell technology, it has to be cheap enough in production to justify wide spread use. Its all about economic payback. I look forward to seeing where this goes. Keep bringing these great articles ecogeek!

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written by Clinch, January 27, 2009

So if it's increasing the absorption from two thirds to three thirds, does that mean an increase in efficiency of 50%, or are most of the previously-reflected rays of wavelengths that can't be harnessed? (e.g. a lot of solar panels can't convert UV into electricity, so if it's mainly UV that's not being reflected, then that's not going to help, and could even cause problems [if the UV energy is just converted to heat, and causes overheating]).

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written by Godzilla_redux, January 28, 2009

What an asshole.

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written by meo, January 28, 2009

@ Godzilla_redux
Please explain your comment. Who/what is an asshole?

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incident angle still important
written by camarco, January 28, 2009

To catch most of the direct sunlight it ist still important to follow the sun. A bad incident angle does not only cause the reflection problems mentioned above, but does also decrease the area perpendicular to the sunrays.
(the bigger the incident angle, the more sunrays "miss" the panel)
Also as mentioned above, non-converted wavelengths will increase panel temperature and decrease conversion efficiency (causing overheating and energy losses throu emissive radiation and convection).
But if these problems can be solved, this is a great step forward to the "perfect" PV Panel :-)

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written by wÓÒ†, January 28, 2009

@ Godzilla_redux
Please explain your comment. Who/what is an asshole?

For our non-native English speakers, an asshole is where the poo comes out.

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re; camarco
written by Yoshi, January 28, 2009

It would be nice to solve the heat problem by using the heat load to heat water for the home, or in a larger installation, to heat oil for a solar thermal system.

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Durability is key
written by Michael, January 30, 2009

Most solar panels for outdoor installations have a protective layer of glass on top of them, which contributes significantly to the reflectivity, and reduces efficiency when not pointed at the sun.

If this surface does not need a glass layer then a major question is how durable the surface is and whether accumulated dust and debris might compromise its efficiency, or whether hail might damage it.

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Facility Maintenance Manager
written by Rene Feliciano, February 03, 2009

The real question here besides the obvious is; can this coating be be applied to an array that is currently installed. That would be awesome. I love these articles.

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Did you have commercialize this panel coating?
written by Francis Lapierre, January 04, 2012

Hi everyone,

I want more information about this coating. Did you have commercialize this panel coating?

What is the name of the company? And what are the costs?

Thanks,

Francis Lapierre

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written by bcbvi, February 13, 2012

All silicon cells already have anti-reflection coatings with 1 or 2 layers which reduce the average reflectivity to roughly 10 or 3% respectively. The 30% mentioned in this article is for a bare piece of silicon which would look shiny like metal. Not a fair comparison. The technology this article is about is 7 layers of materials made from nanorods which would make the cell absorb well at all angles and wavelengths. Is it cheap enough to be viable? I don't know.

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