Automated screening for severe shunting defects in encapsulated series-connected modules [solar cells]

A new technique has been developed for the automated screening of series-connected solar cell modules for severe shunting defects, using large-scale laser scanning. The technique is used to quickly locate and quantify shunting defects in encapsulated modules. All cells with a shunt resistance less than the operator-specified threshold are identified, and their shunt resistance is estimated. A signal map of each faulty cell-often sufficient to locate the shunts-is generated. Access to the two module terminals is the only electrical probing required. The technique is fast, nondestructive, equally successful for single-junction and multijunction cells, and requires operator intervention only when mounting the module in the measurement system. The measurement is available for the photovoltaics community through the National Renewable Energy Laboratory