Life prediction in c-Si solar cell interconnections under in-situ thermal cycling in Kumasi in Ghana

Abstract

Purpose A numerical study on the reliability of soldered interconnects of c-Si solar photovoltaic cells has been conducted. Design/methodology/approach A three-year data (2012–2014) from outdoor weathering of PV modules was used to generate temperature cycle profiles to serve as thermal loads and boundary conditions for the investigation of the thermo-mechanical response of the soldered interconnects when subjected to real outdoor conditions using finite element analysis (FEA) Software (Ansys. 18.2). Two types of soldered interconnections, namely, Sn60Pb40 and Sn3.8Ag0.7Cu (Pb-free), were modelled in this study. Findings Life prediction results from accumulated creep energy density damage show that the solder interconnects will achieve maximum life under the 2014 thermal cycle loading. In particular, the Sn60Pb40 solder interconnection is expected to achieve 14,153 cycles (25.85 years) whilst the Pb-free solder interconnection is expected to achieve 9,249 cycles (16.89 years). Additionally, under the test region average (TRA) thermal cycle, the Pb-free and Pb-Sn solder interconnections are expected to achieve 7,944 cycles (13.69 years) and 12,814 cycles (23.4 years), respectively. The study shows that Sn60Pb40 solder interconnections are likely to exhibit superior reliability over the Pb-free solder interconnections at the test site. Practical implications This study would be useful to electronics manufacturing industry in the search for a suitable alternative to SnPb solders and also the thermo-mechanical reliability research community and manufacturers in the design of robust PV modules. Originality/value The study has provided TRA data/results which could be used to represent the test region instead of a particular year. The study also indicates that more than six thermal cycles are required before any meaningful conclusions can be drawn. Finally, the life of the two types of solders (SnPb and Pb-free) as interconnecting materials for c-Si PV have been predicted for the test region (Kumasi in sub-Saharan Africa).