Nextstep – Subproject: 23% PERC+ and POLO cells for reliable SmartWire modules with solar cell process-based bypass diodes

Dr. Henning Schulte-Huxel
Tel.: +49(0)5151-999 414

Passivated Emitter and Rear Cell (PERC) solar cells are currently being transferred to industrial production at high speed. In the following years, a further strong increase in the market share of PERC cells from currently about 20 % to about 40 % is expected. An exciting further development of the PERC technology is the bifacial PERC+ solar cells, which use an Al finger grid on the rear side instead of the full-area Al contact and can thus absorb stray light with the cell back side. As a result, additional yields of about 10 % can be generated in solar power plants. In the ISFH subproject of the NEXTSTEP project, the promising PERC+ cell technology is to be combined with MeyerBurger SmartWire technology in order to develop PERC+ modules with a very high bifacility of 90 % on the one hand and with a very high monofacial module performance of 325 Wp at a module efficiency of 20.5 % on the other. SmartWire technology minimizes resistance losses of the Al fingers and reduces reflection losses through the connector bands, making it an ideal candidate for bifacial PERC+ module technology. In order to achieve the ambitious module goals, a further development of PERC+ cell technology to efficiencies of more than 23 % is planned in the NEXTSTEP project. In addition, the stability of the SiN anti-reflective coating on the PERC+ front side under UV light will be analyzed and improved for a better spectral utilization of the sunlight. The compatibility of PERC+ cells with SmartWire technology will be evaluated. In order to further reduce module costs, cell processes for the production of bypass diodes in the module are evaluated.

Solar cells with passivating contacts have a very high efficiency potential, but also necessitate additional efforts to integrate them into existing production lines. Passivating contacts based on polysilicon (POLO) have lower quality requirements for layer deposition than “conventional” heterojunctions, so that their production with simplified deposition appears promising. Therefore, this path will also be investigated complementary to PERC. The aim of this project is to achieve an efficiency of at least 23.5 % for solar cells with passivating contacts.


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Duration of the project

01.08.2017 – 31.07.2020


The project is funded by the Federal Ministry for Economic Affairs and Energy under grant no 0324171C. The responsibility for the content of this publication lies with the authors.

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