Nondestructive characterization of solar PV cells defects by means of electroluminescence, infrared thermography, I–V curves and visual tests: Experimental study and comparison

Infrared Thermography for the Detection and Characterization of Photovoltaic Defects: Comparison between Illumination and Dark Conditions

“…The defects present in module 3 do not seem to cause the operation of the bypass diodes. However, in module 1, module 2 and module 3 there is a reduction in the Voc values with respect to module 4, which could indicate the presence of short-circuited cells according to reference [11], as will be further analyzed in the discussion. The user can set the desired inspection setpoint in the computer, usually the current necessary to carry out the inspection, and afterwards, proceeds to send a command to the inverter.…”

“…In this case, the module is forward biased with a power supply, to achieve a current similar to the Isc of the module. Other working points, as 10% of Isc, are commonly selected to better distinguish certain types of failures [11,19].…”

Use of an Indoor Solar Flash Test Device to Evaluate Production Loss Associated to Specific Defects on Photovoltaic Modules

“…Gallardo-Saavedra et al [11] performed an experimental study on the different techniques used for nondestructive characterization of solar PV cells defects: EL, IR thermography, I-V curves and visual tests. In their work, a 60cell polycrystalline module was manufactured ad hoc, with different defective and non-defective cells.…”

Detection, classification and characterization of defects in photovoltaic modules through the use of thermography, electroluminescence, I-V curves and visual analysis

“…In this case, it is used as a contact less method for diagnosing some thermal and electrical defects in PV modules, as one module warmer than others, one bypass diode string warmer than others in the same module, single cells warmer than others without following any pattern or in the lower parts or closer to the frame, a part of a cell warmer, a pointed heating or a bypass diode string part remarkably hotter than others when equally shaded [33]. [96], although IRT will not provide details of the defect patterns in this case, as not all identified defects lead to an increase in temperature. Therefore, sometimes the high resolution of the EL images enables resolving some defects more precisely than in IRT images.…”

“…Therefore, dark-IRT can be performed simultaneously to EL test, while injecting current to the modules. It has been observed from visual inspection of EL and IR images in the fourth quadrant that most of the defects detected in dark IRT images under forward bias condition can also be identified in the EL images while not all the defects detected in the EL images can be detected with dark-IRT, as some broken cells or soldering defects over one or more buses [96]. Therefore, it can be advisable using different techniques to characterize the actual state of the module and to explain its I-V curve.…”