The Influence of Cell Busbare Pattern on PV Module Reliability

Dash-line pattern busbar is recently introduced in solar cell industry for silver paste usage reduction. To evaluate and simulate the endurance of soldering condition and stringer process, thermal cycling test is one of the crucial acceleration approaches for PV module. In this work, traditional full line and various types of dash-line busbar cell among competitors for both P-Multi and P-Mono are assembled into PV modules and undergo thermal cycling test. We present the statistic analysis of power degradation after 200-cycle stress and Electro-Luminescence (EL) inspection for each busbar pattern, and extended thermal cycling testing (600 cycles) is also performed to investigate the failure mechanism. Silver paste composition also plays an important characteristic impacting the reliability. Residue thermal stress tends to release and initiate cracks from corners and edges of dash-line patterns, and the potential risk of cell cracking generation and module power degradation are raised with increasing the dash-line number and sharp corners for busbar pattern.