A Safer Way to Coat Long-Lasting Solar Cells

A venture spun out of two Quebec universities says it has developed a safer way of adding antireflective coatings to crystalline silicon solar cells that also boosts their lifetime energy yield.
In the solar photovoltaic market, even the smallest improvement in efficiency can have a meaningful impact on manufacturers' bottom line, which is why antireflective coatings are so important. These thin coatings, which cause solar cells to appear blue, maximize how much sunlight is absorbed and reduce surface defects that can lower performance.

However, the most popular coating method--the vapor deposition of a silicon nitride film using silane gas--comes with major risks. Silane can ignite when exposed to air; the gas is costly to transport, and silicon cell manufacturers must invest in special storage, ventilation, and other safety measures to prevent accidents.

"The potential for damage is huge," says Ajeet Rohatgi, director of the Photovoltaic Research Center at the Georgia Institute of Technology. Cells coated this way are also affected by a phenomenon called light-induced degradation that occurs once after the first 24 to 48 hours of sunlight exposure. "In a cell with 18 percent efficiency, you will see efficiency drop [almost immediately] to 17.7 or 17.5 percent, and you've lost that for the life of the cell," he says.