Lasers can make solar cells more efficient

May 30th, 2009 - 2:47 pm ICT by ANI  

Washington, May 30 (ANI): Scientists have said that laser technology can contribute to optimizing the manufacturing costs and efficiency of solar cells.

If the latest forecast from the World Energy Council WEC can be believed, global electricity requirements will double in the next 40 years. At the same time, prices for the dwindling resources of petroleum and natural gas are climbing.

“Rising energy prices are making alternative energy sources increasingly cost-effective. Sometime in the coming years, renewable energy sources, such as solar energy, will be competitive, even without subsidization,” explained Dr. Arnold Gillner, head of the microtechnology department at the Fraunhofer Institute for Laser Technology in Aachen, Germany.

“Experts predict that grid parity will be achieved in a few years. This means that the costs and opportunities in the grid will be equal for solar electricity and conventionally generated household electricity,” he said.

Together with his team at the Fraunhofer Institute for Laser Technology ILT in Aachen, this researcher is developing technologies now that will allow faster, better, and cheaper production of solar cells in the future.

“Lasers work quickly, precisely, and without contact. In other words, they are an ideal tool for manufacturing fragile solar cells. In fact, lasers are already being used in production today, but there is still considerable room for process optimization,” said Gillner.

The ILT laser system drills more than 3,000 holes within one second.

Because it is not possible to move the laser source at this speed, the experts have developed optimized manufacturing systems which guide and focuses the light beam at the required points.

“We are currently experimenting with various laser sources and optical systems,” Gillner explained.

“Our goal is to increase the performance to 10,000 holes a second. This is the speed that must be reached in order to drill 10,000 to 20,000 holes into a wafer within the cycle time of the production machines,” he added.

The tiny holes in the wafer - their diameter only 50 micrometers - open up undreamt-of possibilities for the solar cell developers.

“Previously, the electrical contacts were arranged on the top of the cells. The holes make it possible to move the contacts to the back, with the advantage that the electrodes, which currently act as a dark grid to absorb light, disappear. And so the energy yield increases,” sad Gillner.

“The goal is a degree of efficiency of 20 percent in industrially-produced emitter wrap-through (EWT) cells, with a yield of one-third more than classic silicon cells,” he added. (ANI)

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