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80 SMT007 MAGAZINE I AUGUST 2021 I-V curve data of before and aer testing (for both thermal cycle test and damp heat test) are within the specification limit (±5%). e breakage of cell ribbons or wires is a critical failure mode concerning solar modules. e loss of a ribbon/wire does influence the serial resistance of the module and therewith leads to power degradation. To compare the result- ing degradation of a solar module due to rib- bon/wire breakage 1-cell-laminates have been deliberately damaged. Similar work was done by Dethlefsen et al [22] . Our observations also confirm the higher redundancy of the MBB technology compared to the 5BB cell. e fill factor was reduced by 10% when the crack propagation was 2 bb long. Generally, the MBB technique proves to be by far more robust with respect to interconnection breakage, than the 5BB standard interconnection with 5BB cells. is is easily understandable, as the current transport is much better distributed in the MBB technique. Conclusion Factors affecting quality of solder joints in MBB technology are discussed. e soldering challenges arise due to change in technology, process, material, and reliability requirements. It was observed that metallization, solder wire and flux play an important role in determining solder joint strength. Various process parame- ters including wire alignment have additional effect on solder joint peel strength. Higher sol- der volume and flux with excellent wetting characteristics found to yield reliable solder joints. When all process testing parameters are optimized peel strength of over 3N with con- tinuous uniform IMC formation observed. MBB panels in such conditions pass reliability testing as per IEC61215 requirement. SMT007 Acknowledgement: e authors thank Ms. Krithika PM for her non-technical help. References 1. Nian Chen, Abasifreke Ebong, Solar Energy Materials & SolarCells 146(2016)107–113. 2. Walter, J., Tranitz, M., Volk, M., Ebert, C., Eitne, U., 2014. "Multi-wire interconnection of busbar-free solar cells," Energy Procedia 55, 380–388. 3. Schneider, A., Rubin, L., Rubin, G., 2006. "Solar cell efficiency improvement by new metallization techniques—the Day4 electrode concept." In: 4th IEEE World Conference on Photovoltaic Energy Conversion, 1095–1098. 4. T. Söderström et al., Proceedings of the 28th EUPVSEC, Paris (2013), pp. 495-499. 5. Govaerts J, Tom Borgers, Patrizio Manganiello, Maarten Debucquoy, Arvid van der Heide, Hans Goverde, Eszter Voroshazi, Jozef Szlufcik and Jef Poortmans, "Multi-wire interconnecting for multi- busbar interdigitated back-contact cells: opportu- nities and pitfalls in cell-module co-design," 33rd European Photovoltaic Solar Energy Conference and Exhibition. 6. Alejandro de la Fuente Vornbrock Ven- kateswaran Subbaraman, "Photovoltaic module with flexible circuit," US patent 9842945B2 2014. 7. Geipel T., Moeller, M., Walter, J., Kraft, A. and Eit- ner, U. (2017). "Intermetallic compounds in solar cell interconnections: Microstructure and growth kinet- ics," Solar Energy & Solar Cells, 159, pp. 370. 8. Rendler, L. C., Kraft, A., Ebert, C., Wiese, S., and Eitner, U. (2016). "Investigation of Thermomechani- cal Stress in Solar Cells with Multi Busbar Intercon- nection by Finite Element Modeling," Proceedings of the 32nd European Photovoltaic Solar Energy Conference and Exhibition, Munich, Germany (pp. 94-98). 9. Uichi Itoh ManabuYoshidaa HideoTokuhisaa Kohichi Takeuchi Yasuyuki Takemura, "Solder Joint Failure Modes in the Conventional Crystalline Si Module," Energy Procedia, Vol 55, 2014, pp 464- 468. 10. Jae-Seong Jeong, Nochang Park, Changwoon Han, "Field failure mechanism study of solder inter- connection for crystalline silicon photovoltaic mod- ule," Microelectronics Reliability, Volume 52, Issues 9–10, September–October 2012, pp 2326-2330 . 11. DIN EN 50461: Solar cells—Datasheet infor- mation and product data for crystalline silicon solar cells (2007). 12. N.S. Pujari, J. Sundaramurthy, S. Sarkar, E. Poh, C. Bilgrien, "Solder Joint Analysis of Tin-Lead and Bismuth Based Lead-Free PV Ribbons in High Throughput Manufacturing," Proceedings of the 35th EUPVSEC, Brussels (2018), pp. 210-214. 13. Shipley, J. (1975). "Influence of Flux, Substrate and Solder Composition on Solder Wetting," 4th AWS International Soldering Conference held dur-