centrotherm photovoltaics AGs evolutionary research and development strategy, which also allows its turnkey customers to benefit from solar cell development progress through technology and equipment upgrades, is reaping rewards: three turnkey production lines owned by a Taiwanese customer are currently being retrofitted with a selective emitter technology upgrade package. The photovoltaics specialist is engaged in advanced contract negotiations with renowned clients in Asia.

"Our strategy of upgrading existing production lines with selective emitter technology is proving highly successful. The market is showing great interest in such products," as Dr. Peter Fath, CTO at centrotherm photovoltaics, explained. He went on to add, "Both existing and new customers can produce even more efficiently with our upgrade packages. Last, but not least, electricity customers also benefit." The global sales potential for the upgrades lies in the triple-digit millions of Euros range.

Upgrade packages boost cell efficiency to a peak value of up to 18.5 percent, and cut module costs by three percent

Not only will new customers benefit from the efficiency enhancements as the result of continuous innovation, but also those clients who have already been relying on tried and tested centrotherm technology for years. This led the Swabian company to develop two upgrade packages that raise cell efficiency by up to 0.5 percentage points. This allows peak results of more than 17 percent efficiency on multi-crystalline material, and of up to 18.5 percent on mono-crystalline material – depending on wafer material quality. 

The space-saving basic design for a 60 MW line includes two laser islands, and improves cell efficiency by up to 0.3 percentage points according to information provided by the company. In the case of the premium product, featuring two laser islands, an oxidation furnace and wet process system, cell efficiency is up to 0.5 percentage points higher. The improved light yield offers a double benefit: module costs fall by around 3 percent, while electricity customers also benefit. A 0.5 percentage points higher efficiency results arithmetically in three cents lower production costs per Watt peak (Wp), according to a study produced by LBBW*.

centrotherm photovoltaics will also continue to back this evolutionary development strategy in the future: "The continuous optimization of production processes forms the centerpiece of our R&D roadmap," commented Dr. Fath. "This roadmap envisages an annual efficiency enhancement of 0.5 percent in the mono-crystalline cell area, and of 0.4 percent to 0.5 percent in the multi-crystalline cell area. This is the only way in which we will secure our position as pioneering thought leader and pace setters within the solar sector."

The potential for selective emitter technology

The emitter coating is the uppermost coating of a solar cell exposed to light. Conventional emitters exhibit a high phosphorus concentration. The share of light that the emitter absorbs is largely converted into heat, thereby generating no electricity within the solar cell. The selective emitter technology significantly diminishes this loss insofar as it imposes a high phosphorus concentration on only a partial area within the contact area where it is essential. Consequently, more light is converted into electricity.

* LBBW Sector Alert "Energy & Power Technology" of September 25, 2009