Blaubeuren, Germany – The strategic laser processing cooperation between Rofin-Baasel Lasertech GmbH & Co. KG and centrotherm photovoltaics AG is proving worthwhile in the selective emitter technology area. Dongfang Magi Solar, a Chinese customer of centrotherm photovoltaics, is achieving an average efficiency of more than 18.5%, and charges of up to 18.7%, through the deployment of the recently installed upgrade package entailing a laser-based selective emitter. These cell efficiencies are significantly above the levels of around 18% that are standard in the market.
"Deployment of the ROFIN laser, which requires only minor additional investment costs, significantly improves solar cells' efficiency," said Dr. Peter Fath, CTO of centrotherm photovoltaics AG, on the strategic cooperation that has existed since September 2009. "This reduces manufacturing costs per watt peak, and allows our customers to extend their cost leadership."
For this year, the company anticipates that selective emitter technology will hold a sales potential in the double-digit area in millions of euros. The company has proven higher efficiencies in mass production through upgrades at further cell manufacturers. The selective emitter is currently being retrofitted at several Asian customers. In addition, turnkey projects for production lines for mono- and multi-crystalline silicon (Si) solar cells with selective emitter technology have been successfully concluded. Several millions of highly efficient selective emitter solar cells have already been manufactured in ongoing three-shift production.
The technology to produce selective emitter structures that has been developed with Rofin Laser boosts solar cell efficiency by up to 0.4 percentage points. Conventional emitters exhibit a high degree of phosphorus concentration, which results in a significant portion of the incoming light being converted into heat instead of electricity. Selective emitter technology significantly reduces this heat loss by using the laser to position the highly phosphorus concentration in only the requisite areas. The solar cell converts more light into electricity as a consequence.
A further application area for the ROFIN laser is in centrotherm photovoltaics' centaurus rear side technology. The new rear side technology replaces the aluminum rear side through a passivation coating with local contacts that covers the entire area. This improves sensitivity to long-wave light, and more electricity is generated. Cell voltage is also improved. Efficiencies of significantly above 19% are achieved as a result.
"Lasers represent universal materials processing tools, and are excellently suited to photovoltaics applications," said Stephan Geiger, managing director of Rofin Baasel Lasertech GmbH & Co. KG. "With our lasers, we ensure that even higher performing solar cells are produced with selective emitter technology."