Researchers at Rensselaer Polytechnic Institute have discovered and demonstrated a new method for overcoming two major hurdles facing solar energy. By developing a new antireflective coating that boosts the amount of sunlight captured by solar panels and allows those panels to absorb the entire solar spectrum from nearly any angle, the research team has moved academia and industry closer to realizing high-efficiency, cost-effective solar power.
“To get maximum efficiency when converting solar power into electricity, you want a solar panel that can absorb nearly every single photon of light, regardless of the sun’s position in the sky,” said Shawn-Yu Lin, professor of physics at Rensselaer and a member of the university’s Future Chips Constellation, who led the research project. “Our new antireflective coating makes this possible.”
Note that these numbers do not indicate the percentage of the light that gets converted into electricity. But solar cells that absorb more photons will probably increase their electric power output roughly proportionate to the amount of additional light absorbed. I say roughly because the light that would otherwise get reflected away might be at frequencies that do not convert well to electrons.
An untreated silicon solar cell only absorbs 67.4 percent of sunlight shone upon it — meaning that nearly one-third of that sunlight is reflected away and thus unharvestable. From an economic and efficiency perspective, this unharvested light is wasted potential and a major barrier hampering the proliferation and widespread adoption of solar power. After a silicon surface was treated with Lin’s new nanoengineered reflective coating, however, the material absorbed 96.21 percent of sunlight shone upon it — meaning that only 3.79 percent of the sunlight was reflected and unharvested. This huge gain in absorption was consistent across the entire spectrum of sunlight, from UV to visible light and infrared, and moves solar power a significant step forward toward economic viability.
Increased absorption combined with solar concentrators could greatly reduce the amount of PV material needed per amount of electricity produced. This will work in favor of more expensive high conversion efficiency PV materials. So the cheaper thin film PV will effectively face more competition from the more expensive and more efficient silicon-based PV.
|Share |||Randall Parker, 2008 November 03 11:15 PM Energy Solar|