Optomec Boosts Solar Cell Efficiency With Fine-Line Printing

The company's material-depositing technology, which is being developed for commercial launch, can boost a solar cell's electricity-generating ability, according to research by Fraunhofer.

Research from Germany's Fraunhofer Institute for Solar Energy Systems has shown that a material-depositing technology by Optomec could boost solar cell efficiency by more than 2 percentage points.

Cyrstalline-silicon solar cells treated with Optomec's Aerosol Jet system can reach 20.3 percent efficiency, the company said this week. That means the cell can convert 20.3 percent of the sunlight that hits it into electricity.

In comparison, cells made with a screen-printing system commonly used today can achieve 16 percent to 18 percent efficiency.

Optomec, a long-time electronics manufacturing equipment maker, is entering the solar market with the Aerosol Jet system. In May, the Albuquerque, N.M. company said it was partnering with Manz Automation in Germany to commercialize the technology.

Optomec will make the key components while Manz will assemble them into a system for the marketplace. Optomec and Manz plan to provide trial systems to customers during the firs half of 2009, said Ken Vartanian, marketing director for Optomec. He declined to name the customers.

The company's technology deposits a mix of glass and silver to form collector lines and bus bars on solar cells. In a working solar cell, collector lines take the electricity generated and send it to the bus bars as part of the process of ferrying the power produced from an energy system.

The number of collector lines on each cell can vary. Typically a cell has roughly 80 collector lines and two or more bus bars, Vartanian said.

"If you think bus bars as the superhigyway and collector lines as the side streets feeding into it," Vartanian said.

He said the technology can create much thinner collector lines than a screen-printing system, so that more space on each solar cell is exposed to the sunlight for generating power.

Lines made with Aerosol jets have a width of 40 microns to 50 microns, Vartanian said. With screen-printing, the width would reach 100 microns to 120 microns, he added.

Optomec will be competing with some established players. Companies that make screen-printing systems include Applied Materials in Santa Clara, Calif., and GT Solar in Merrimack, N.H.

Optomec has been developing material-printing technology for electronics and life sciences markets for years. Spotting an opportunity in the solar market, in 2007 the company launched its Aerosol Jet Solar Lab system, which enables solar cell makers and researchers to take the technology on a test run.

Though Solar Lab, Optomec hopes to convince companies to buy the commercial system it's developing with Manz. The Solar Lab costs about $300,000 in the United States, and it is a little higher elsewhere after taking shipping and other costs into account.

The Solar Lab system is not automated and has 10 nozzles instead of the 40 planned for the commercial system, Vartanian said.

Fraunhofer became a customer three years ago, and a researcher there presented the institute's findings at a European Union-sponsored workshop in the Netherlands in October (see presentation).