Lasers Improve Solar Efficiency
Source: Daily Tech, Jason Mick (3/9/11)
"Researchers used laser scribing to improve inter-cell power transfer."
Much work has gone into improving the base efficiency of solar cells and find optimal materials for the cells. Purdue University's Center for Laser-Based Manufacturing instead looked at another source of efficiency and power loss—cell interconnects.
Typically solar cells are manufactured similar to microprocessors, using vapor deposition techniques on a semiconductor substrate. Metal interconnects were used to link cells.
But more recently thin film solar cells have been taking off. Thin films can be made flexible and transparent. And they use less material, making them potentially cheaper. However, they require new processes to create. Instead of bulky metal interconnects, they use tiny interconnects called "microchannels" to electrically connect individual cells allowing thin film cell arrays to be created.
Yung Shin, Purdue professor of mechanical engineering, "The efficiency of solar cells depends largely on how accurate your scribing of microchannels is."
Using the cutting edge laser, the team cut away chunks of material using a process called "cold ablation." Where similar efforts had failed in the past was that the cutting process was too slow and heated the material, creating defects and damage.
The ultra-fast laser, though, creates pulses lasting only picoseconds. It chips along creating a damage-free ultra-smooth, sharply defined microchannel.
Currently thin film cells account for 20% of the global market in terms of watts generated. In two years—by 2013—that total is expected to rise to 31%.
Thus you can expect to see this microchanneling technique to be incorporated into production designs sooner rather than later.