|CC BY-SA 2.0 russf|
In labs, researchers have been able to hit efficiencies as high as 44.7 percent, but the start-up Semprius says they have a technique for stacking solar cells that would lead to that magic 50 percent number, and not just in a lab. Not only that, but because the solar cells are small and cheap to manufacture, the company believes that this technology could also lead to solar power cheaper than natural gas.
MIT Technology Review says, "Semprius has come up with three key innovations: a cheap, fast way to stack cells, a proprietary way to electrically connect cells, and a new kind of glue for holding the cells together. In its designs, Semprius uses tiny individual solar cells, each just a millimeter across. That reduces costs for cooling and also helps improve efficiency."
The company thinks that within three to five years it will be able to build solar cells consisting of two stacked multi-junction devices, which would be a total of five or six semiconductors. That device could actually go beyond 50 percent efficiency.
Even bette, at 80 to 100 megawatts a year of manufacturing capacity, solar cells achieving 50 percent efficiency could reach costs of five cents per kilowatt-hour, which beats the current price of natural gas at 6.4 cents per kilowatt-hour.