Solar cell twice efficient as standard solar cell models

The best silicon solar cells on the market convert 22 percent of the sunlight they receive into electricity, but Boeing-Spectrolab has developed a new cell that nearly doubles that number, and other companies are following suit.

Physics limits traditional solar cells to a maximum efficiency of 26 percent, because silicon only interacts with a certain part of the light spectrum. Achieving an efficiency of 40.7 percent because they contain an extra layer of concentrators — a thin lens that focuses the sunlight onto the cell — and additional materials that react with more of the spectrum. The Department of Energy has been sponsoring ways to overcome the 40 percent barrier.

Although they are more expensive to make, these “multi-junction” cells could lower the cost of solar power to roughly $3 a watt, including installation costs and other expenses, compared to the $8 a watt cost of traditional solar cells, before government rebates. Ultimately, solar power proponents would like to lower the cost to $1 a watt, not including incentives or rebates.

Lawrence Berkely National Laboratories researchers, partly sponsored by the DoE, said earlier this year that 45 percent efficiency could be achieved with cells made from zinc-manganese-tellurium combined with a few oxygen atoms. The technology has been licensed to RoseStreet Labs in Arizona, but only time will tell if it is economically feasible to make the material into solar cells. Additionally, industry giant Sharp Solar has developed a cell that can achieve 36 percent efficiency using a concentrator and elements in the III and V columns of the periodic table instead of silicon.