Shutter Technique for Noninvasive Individual Cell Characterization in Sealed CPV Modules

An optical shutter technique for quality control and degradation analysis of concentrating photovoltaic (CPV) modules is presented. Shuttering configurations are described and used to determine individual component degradation or failure in field-exposed commercial modules. Cells are shuttered in specific patterns, intentionally engaging internal bypass diodes, and current-voltage (I-V) curves are measured at the housing terminals of the sealed module. Individual cell characteristics may be qualitatively determined by contrasting module I-V responses to different shutter configurations and quantitatively determined by fitting an extended equivalent circuit model to the shutter data.