21 percent efficiency rate achieved on 156 mm wafer using Roth & Rau`s new high-efficiency technology

HOHENSTEIN-ERNSTTHAL/NEUCHATEL, GERMANY: By achieving an efficiency rate of 21 percent, Roth & Rau AG has reached a new milestone in the development of its high-efficiency technology.

Solar cells based on heterojunction technology (HJT) are characterised in particular by their high output efficiency rates. Moreover, the low temperature coefficient means that they achieve a higher energy yield. At an output efficiency rate of 20 percent, this technology thus already reduces solar electricity generation costs by around 15 percent compared with the latest technology available for traditional crystalline solar cells.

Roth & Rau already presented the world`s first heterojunction solar cells with efficiency rates of 20 percent produced on industrial 156 mm mono-crystalline wafers at the 26th European Photovoltaic Solar Energy Conference and Exhibition (EUPVSEC) held in Hamburg at the beginning of September 2011. These cell results have since been verified by the Fraunhofer Institute for Solar Energy Systems (ISE) and further progress has been made at Roth & Rau`s research line in Neuchâtel in close cooperation with the EPFL/IMT research institute located there. The latest results for 156 mm cells now correspond to a superb rate of 21 percent.

“With our current results, we have taken a further step towards achieving grid parity. It is now clear that very high cell efficiency rates are achievable with heterojunction technology. Now it is a question of transferring these results to mass production systems“, commented Dr. Egbert Vetter, VP for R&D at Roth & Rau AG, with regard to the latest progress.

At its Technology Centre in Hohenstein-Ernstthal, Roth & Rau is pressing ahead with its efforts to transfer the results of the cell technology development work in Neuchâtel to mass production systems. Using the HELiA coating systems, which represent the core components of a production line for solar cells based on heterojunction technology, the company has currently achieved cell efficiencies of 20 percent.

Given the great progress made in recent months, Roth & Rau is confident that the results now achieved will also be available for use in mass production in the near future.