Published on December 9th, 2013 | by Tina Casey8
Natcore Aims To Make Black Silicon Solar Cells Even Cheaper
The solar company Natcore Technologies is set to take a huge bite out of the cost of producing solar cells while reducing the amount of manufacturing-related hazardous effluents. The key is a new low temperature laser process that Natcore plans to introduce, which will eliminate the need for a high temperature diffusion furnace.
Natcore has been working with the National Renewable Energy Laboratory and other partners to perfect its black silicon technology. Just around this time last year it announced that it completed the design of a complete low-cost black silicon solar cell production system at its New York facility, resulting in the potential for a 23.5 percent cut production costs according to an independent study cited by Natcore.
The Road To Super Cheap Black Silicon Solar Cells
The laser system could result in even greater savings.
In conventional solar cell manufacturing, materials are added to the surface of the cell (a process called doping) by melting them on in a furnace, which involves a considerable amount of waste heat. Typically, the furnace reaches temperatures of up to 900 degrees centigrade.
In contrast, laser doping focuses all of its energy on localized points. It takes less than a millisecond, wasting far less energy and minimizing the risk of damaging the solar cell.
According to Natcore officials, the process will also eliminate hazardous materials used in the conventional production process, including silane and phosphorous oxychloride.
Natcore isn’t saying what laser it is using, but it has identified a company that it is working with to custom-make a system for their R&D facility.
Don’t Forget Black Metals!
Black silicon refers to silicon wafers etched with billions of nano-sized holes per square inch. That creates a new level of efficiency, as described by NREL:
The holes and silicon walls are smaller than the light wavelengths hitting them, so the light doesn’t recognize any sudden change in density at the surface and, thus, don’t reflect back into the atmosphere as wasted energy. The researchers controlled the nanoshapes and the chemical composition of the surface to reach record solar cell efficiencies for this ‘black silicon’ material.
The wafer is not actually colored black, but the nanoholes make it appear darker. It’s worth noting, by the way, that Natcore has some competition in this area, for example from Germany’s Fraunhofer-Gesellschaft institute.
Meanwhile, researchers at Lawrence Livermore National Laboratory have been working on a “black metals” process that deploys the plasmonic effect to harvest energy from a greater span of the solar spectrum.
The basic concept is similar to black silicon, but instead of using nanoholes, the structures in black metal are pillar-like nanofilaments.
Projects like these demonstrate that solar tech has yet to find its bottom cost, as efficiencies continue to rise and production costs fall.
As for the “soft costs” of a solar installation including labor and third-party financing, those are also being addressed by new Department of Energy initiatives such as the Most Affordable Rooftop Solar Prize.
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