In the pursuit of squeezing more current from a solar cell, Harvard spin-off SiOnyx is using lasers.
The company today announced third-party tests found its Black Silicon laser texturing process increases the efficiency of traditional silicon cells by 0.3 percent. That may sound minor, but it takes solar manufacturers about a year to achieve that sort of gain through process changes, said Chris Vineis, director of solar technology at SiOnyx.
The company plans to license its technology, which essentially scans a pattern on the surface of solar-grade silicon, to solar manufacturers. In traditional solar production, pure silicon is sliced into square wafers, which are treated in multiple steps to make a cell, which are then assembled into a panel. The process can be adopted by both wafer and cell manufacturers, Vineis said.
The laser texturing reduces the reflectivity of the silicon, turning it dark so it can absorb more light and generate more current. The technology allows manufacturers to use wafers that are 20 percent thinner, saving 10 percent to 15 percent on cost. It also yields more consistent efficiency among different solar cells, which can vary based on the crystalline structure on the surface, explained Vineis.
The performance improvement was measured by German research institute ISC Konstanz, which found an average efficiency of 17 percent with the SiOnyx process.
The laser process is designed as a replacement for a chemical step now used by solar manufacturers. SiOnyx is also developing a laser process to boost efficiency by 1 percent, which can work with advanced manufacturing techniques now only used by a few solar providers, Vineis added.
The main part of SiOnyx's business is in image sensors, such as chips for night vision goggles and other applications. In that case, the company plans to make and sell silicon chips itself, rather than license technology, Vineis said.
SiOnyx's laser texturing represents one of multiple techniques technology companies are developing to make an incremental improvement to solar cell efficiency and cost by modifying existing production lines.