Publications Details
Effects of Frame Constraints on Internal Module Damage during Mechanical Load Testing
Detailed finite element models of a 60-cell crystalline silicon photovoltaic module undergoing a ±1.0 and ±2.4 kPa pressure load were simulated to compare differences created by a constrained frame boundary condition versus replicating manufacturer recommended rack mounting. Module deflection, interconnect strain, and first principal stresses on cell volumes were used as comparison metrics to assess how internal module damage was affected. Average results across all loads scenarios showed that constraining the frame of the module to its initial unloaded plane reduced peak deflections by approximately 13%, interconnect strains by 11%, and first principal stress by 11% when compared to a module with correctly modeled racking. Analysis of results based on damage metrics indicated that the constrained boundary condition reduced interconnect stress at most locations and increased fatigue life by an average of 34%, and likewise reduced the average probability of cell fracture by 82%, though individual results were highly variable. Nonetheless, location-specific trends were generally consistent across constraint methodologies, indicating that the constraint simplification can be applied successfully if corrected for with increased load, additional test cycles, or an informed interpretation of results. The goal of this work was to exercise a methodology for quantifying differences created by a simplified test constraint setup, since expedient experimental simplifications are often used or considered to reduce the complexity of exploratory mechanical tests not related to standards qualification.