Solar power, from large-scale power plants to residential solar installations, has seen dramatic growth even as many declared the end of the solar era. And while the industry has come across stumbling blocks such as reticence from state governments, according to Environment & Energy Publishing, some new developments in the technology could help push solar electricity even further into the mainstream.
In crystalline silicon solar cells, which account for the vast majority of all solar panels in rooftop solar installations and many larger systems as well, silicon is heated until molten. SolarBuzz explains that most manufacturers must bring the material up to as much as 1,600 degrees Celsius, or more than 2,900 degrees Fahrenheit. For technologies that require purer silicon, manufacturers must sometimes maintain this temperature for days as the crystal is formed, but the energy costs can prove dramatic regardless.
Particularly given the goal of the solar industry of reducing the need for fossil fuels, such energy inefficient process can prove counter-productive.
In an attempt to solve this method, MIT’s Technology Review reports that the NREL adopted an approach that is well-known in the manufacture of microchips and other electronics. Known as an optical cavity furnace, this technology uses intense light to heat up the silicon. Unlike earlier methods, the NREL’s furnace makes use of heavily insulated and highly reflective ceramic materials that are shaped exactingly to best focus the light where it is most needed.
This process dramatically improves the efficiency of these furnaces and allows for incredibly nuanced control of how solar cells are formed. The most immediate benefit, particularly where the cost of solar cells is concerned, is that the process reduces the energy needed by around 50 percent.
“With all solar cells, optics has a big advantage because solar cells are designed to absorb light very efficiently,” NREL principal engineer Bhushan Sopori said in a statement. “You can do a lot of things. You can heat it very fast and tailor its temperature profile so it’s almost perfectly uniform.”
In addition, the manufacturing of solar cells involves certain chemical reactions and other processes that can be improved through the fine control provided by the optical surface. Thus far the researchers, fairly early in their development of this technology, have been able to increase the efficiency of the solar cells about 0.5 percent. This already represents a substantial improvement given that the solar panels being sold commercially generally range from as low as 8 percent to, rarely, as high as 20 percent efficient.
However, the researchers believe that with further refining of the furnace they could actually increase cell efficiencies as much as 4 percentage point, roughly 25 percent increase over the same cells manufactured through traditional processes.
Other improvements could help to bring costs down through materials costs. PV Magazine reports that Japanese chemical company Kaneka and Belgium-based research group imec have created a solar cell that reached 21 percent efficiency, a relatively high mark above current industry standards, making use of copper contacts in place of the traditional printer silver. Aside from being more resilient and reliable in manufacturing purposes, copper is substantially less expensive than silver and less susceptible to price swings created by the investment market.
Reuters reports that the growing demand for silver in the solar sector, which nearly doubled from 2009 to 2010, has forced many companies to find ways to cut back on the precious metal’s use. Accounting for nearly one-tenth of solar manufacturers’ materials costs, a switch to copper could prove a huge benefit to the cost of solar installations.
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