Application of Infrared Thermography for Cell-Level Power Estimation of PID-s Impacted Crystalline Silicon PV Module

The potential-induced degradation shunting (PID-s) is a severe degradation mechanism that shows a significant drop in a module power in a very short duration. Hence, timely qualitative and quantitative evaluation of PID-s is required for taking preventive measures. Current–voltage (
I–V)
characterization and electroluminescence (EL) imaging are widely used to assess the PID-s; however, the use of
I–V
is cumbersome in the field, whereas EL cannot quantify severely affected PID-s modules since heavily shunted cells do not have active EL emission. In this article, a quantitative application of inverse infrared (IR
_INV
) imaging with biasing (performed under conditions similar to EL) is proposed for the assessment of mild to severe forms of PID-s. The relationship between cell power loss and heat dissipation with PID-s progression is studied. It was observed that PID-s follows a characteristic temperature pattern in which cell temperature is proportional to the severity of PID-s. Hence, temperature is used as a determinant of PID-s. Based on this analysis, the generalized model is developed to estimate the cell-level power loss caused by PID-s using the cell temperatures obtained from IR
_INV
images. The proposed model is experimentally tested on 20 mono- and polycrystalline silicon photovoltaic modules containing mild to severe states of PID-s. Results have shown that the proposed model enables the estimation of PID-s power loss within a module with a maximum relative error of
$ \pm $
5%.