Evaluating the Field Reliability of Half-Cut Cell Modules Under Partial Shading and Reverse-Bias Stress Conditions

Abstract

Half-cut cell architectures reduce series-resistance losses and improve partial-shading energy yield through their split-string configuration, but the redistribution of reverse-bias stress under partial shade introduces failure modes not fully captured by conventional reliability protocols. This study presents the results of a 24-month controlled outdoor exposure of paired full-cell and half-cut modules across two climatic regions, with periodic dark IV characterization, electroluminescence imaging, and infrared thermography. We quantify the rate of solder-bond degradation, hotspot formation, and bypass-diode activation under realistic partial-shade duty cycles, and we report a higher prevalence of cell-level micro-shunt formation in half-cut variants under sustained reverse bias. The findings inform module design refinements and recommend supplementary protocols for inclusion in customer qualification frameworks.