A silicon solar panel up close
It is such a basic idea, it is surprising that someone didn’t point this out earlier. The gorgeous, deep-blue PV panels that gleam in the sunlight can be a lot more efficient if they were a less reflective. Of course! Just think that when the light bouncing off solar panels is absorbed instead, dull solar panels can generate more electricity.
Silicon is the primary ingredient of most solar panels manufactured. However, bare silicon cells only absorb two-thirds of sunlight energy. When glass is added to the top for protection, reflection increases and efficiency goes down. As explained in NewScientist:
“To address that, anti-reflective coatings are added to the silicon of commercial solar cells, but they still allow much light to be reflected. Most cells use a coating that is designed to force reflecting photons to get tangled up with new photons striking the cell.”
Earlier this month, scientists unveiled a new solar cell with record-breaking efficiency. Have you guessed it yet? Yep – it was a dull solar panel. Credit goes to Martin Green, at the University of South Wales, Australia, who led the research team to the new world record.
The technical operation is explained:
“An anti-reflective surface cuts reflection to 3% across most of both the visible and infrared spectrums, helping them to convert 25% of light energy into electricity.”
Even if you are not a scientist, it is easy to understand that 25% efficiency is superb when it comes to solar panels. Talk about turning something dull into a bright idea!
Dull solar panels are created in part by using an anti-reflective coat comprised of silica and titanium dioxide. Seven layers of this coat work together to “smooth out” the entry of light into the solar cell, minimizing reflectance. Each layer contains more titanium dioxide than the previous one, in effect drawing the photons in, instead of allowing them to bounce out.
The 7-layer coating was developed by a team led by Shawn-Yu Lin at the Rensselaer Polytechnic Institute in Troy, New York.
Are you as impressed as I am? Well, you may be wondering about the cost of dull solar panels, compared to ordinary PV panels. The seven-layer coating only adds 4% to the total cost of the panels, but it cuts the reflection across the light spectrum to an impressive 4%. The trade-off is gained in the greater efficiency and much lower reflectivity.
What about the protective glass cover for the panels? Scientists are also tackling that issue, inspired in part by the eyes of a moth. Moths’ eyes have evolved to not waste any available light, so why not create glass taking cues from nature? The following description of non-reflective glass explains the advanced design:
“The design consists of densely-packed, 500-nanometre-tall spikes, tapering from a point at the top to wide at the bottom.”
The effect is much like the 7-layer dull solar panel coating. And the results are equally impressive: reflection is cut down to only 5% across the light spectrums.
Kudos go to the stellar researchers, Peng Jiang and Chih-Hung Sun at the University of Florida, and Bin Jiang at Portland State University for their advanced research on non-reflective solar panel glass coatings. These brilliant minds plan to establish a start-up company to manufacture and sell more efficient solar panels.
From everything I have read, dull solar panels seem to be the next big thing in solar energy! Could it be that within the next 5-10 years, the shiny PV panels we now see on buildings will be a thing of the past? What do you think about the bright ideas of these brilliant scientists? Personally, it sure makes me wish I paid closer attention to my high school chemistry teacher.
July 9th, 2009 at 12:13 am
Me! me! me! me! me! me! me! Just ignore the earth. Everybody who has PV panels can be oh so smug and self-righteous with their savings while ignoring the upcoming Global warming accelerator. The Earth's loss of albedo. Seems to me that to increase the Earth's albedo while photoing your voltaics is the more desired direction for research. Come on folks let's get out of the tunnel vision and maybe invent some white or transparent solar cells with a reflective background. Put your thinking-caps on boys and girls we've got to take a broader view.
November 20th, 2009 at 9:40 am
Hi, good people of the future. Solar panels are very good, when you live far from the grid and also cost effective in this case. But! Have you ever REALLY thought about the green issue regarding this product? First; is it recyclable and how? 2nd; imagin half a tonne of battery in every household. 3rd; are the everage people ready to do basic maintenance on the system? – hence the cost and honesty of professional servicing. What will happen to all those glass laminates in the long run? Or, we should simply sweep the issue under the carpet and leave it for our grand children to try and clean up our mess? I have over fifteen year of experience in the manufacturing process and i have panels. Carbon is 100% recyclable.