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.
via: Device Daily
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