Roth & Rau achieve 21% efficiency on 156mm wafer

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  Si-HJT cell structure. Image: Roth & Rau.

Roth & Rau's has recently improved the cell efficiency on their heterojunction solar cells (HJT) to 21% efficiency on 156mm wafers. Presented at the European Photovoltaic Solar Energy Conference and Exhibition in Hamburg at the beginning of September this year, Roth & Rau achieved the first silicon heterojunction cell on 6 inch wafers at an efficiency rating of 20%. This result was later independently confirmed at Fraunhofer Institute for Solar Energy Systems (ISE).

At an output efficiency rate of 20%, this technology was already capable of reducing solar electricity generation costs by around 15% compared with the latest technology available for traditional crystalline solar cells. Further progress was then made at Roth & Rau’s Solar cells research line in Neuchâtel, in close cooperation with the EPFL/IMT research institute, to bring it up to 21%. The HJT is characterized in particular by its high output efficiency rates. Moreover, the low temperature coefficient means that they achieve a higher energy yield.

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%.

“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.