Stanford University has designed through Solar Junction company high-efficiency, multi-junction solar cells for concentrating photovoltaic (CPV) solar collectors. The new concept convert sunlight into electricity efficiently using different materials than the usual silicon cell and multiple semiconductors within a single package.
The costs will become down as regard of the efficiency improvements and higher concentration levels as the CPV solar collectors can concentrate light twice the efficiency available in the last few years.
But the Chinese now has reached another solution that is going to be more cheaper and more effective way to make the solar panels by the Suntech Power. The new technology lies in the wafers of the solar panels.
The most efficient silicon solar cells use wafers consisting of a single crystal of silicon. When made by the new process, these high-quality “monocrystalline” wafers cost about the same as lower-quality multicrystalline wafers, or potentially half as much as monocrystalline wafers made by conventional processes. (Wafer cost is only part of the cost of solar power, which is why a process that may cost half as much only reduces the overall cost by 10 to 20 percent.)
The idea underlying the process was patented more than 20 years ago but never commercially developed by the patent owners. The patents expired about three years ago, and several companies—JA Solar, LDK Solar, and Renesola, in addition to Suntech—recently announced that they had succeeded in making the process work.
Stuart Wenham, Suntech’s CTO, described the advance at a solar conference this week in Seattle, and said the company has already started selling solar panels made using the process.
This news may spell trouble for businesses in the United States and elsewhere hoping to commercialize new thin-film solar technologies. In theory, thin-film technology is cheaper per watt than silicon technology.
Making high-quality monocrystalline wafers ordinarily involves heating silicon to over 1,400 ° C (higher than its melting point), and then dipping a seed crystal into the melt. An ingot from which the wafers will be cut is formed by gradually pulling the seed up as the silicon crystallizes around it. This happens over the course of one to two days, during which time the pool of silicon must be kept hot—which takes a lot of energy. Both the energy consumption and the slow rate of production make the process expensive. Making multicrystalline ingots is faster and less energy-intensive—the silicon is melted and then cooled. There is no need to keep the silicon hot, saving energy, but cells made from these materials are much less efficient.