Laser for More Capacity

New manufacturing techniques increase efficiency and reduce costs.

Silicon wafers are still predominantly mechanically processed into cells. As a result, precise and rapid processing of thin wafers is not possible. Now, lasers should bring more precision and speed into solar production. Researchers and engineers are working intently on new processes.

The photovoltaics (PV) market is in upheaval. In comparison to a year ago, solar modules are no longer being snatched out of manufacturers’ hands. The competition is huge. In the meantime, customers have started asking about efficiency and lifespan – and then how many kilowatt hours their solar system supplies per Euro or Dollar of investment.

In just a few years, solar power should, even in Germany, achieve the price level of conventionally produced energy. This is only possible if solar technology becomes more efficient and, especially, cheaper. Competition is forcing companies to produce more efficiently. And light is helping them to do this. Because lasers work quickly, extremely precisely, without contact and wear-free. This makes them an ideal tool for cell and module manufacturers.

Lasers are versatile: They produce tiny holes and the most delicate trenches, they clean surfaces, they fuse the thinnest of layers and they weld or solder materials. Virtually all PV companies are trialling such options on pilot lines. However, in production to date, lasers are only being used to label the solar cells and isolate the edges. Uwe Stute from Trumpf Laser explains that “micro-processing lasers with pulse durations of several tens of nanoseconds electrically create a trench along the edge, along the front and rear sides of the cell.” However, this will change in the future. “The times, when crystalline solar cells, which still dominate the market with in excess of a 90 percent share, are mechanically drilled or cut should soon be over,” says Stute. He says two trends are door openers for lasers: Firstly, the wafers are becoming thinner and thinner in order to save expensive silicon. Secondly, manufacturers are striving for production rates of one cell per second. Without the use of lasers, this is virtually impossible.