Diagnostics of PID Early Stage in PV Systems

Abstract

Potential induced degradation (PID) is a serious threat for the photovoltaic (PV) industry. The risk of PID may increase with increasing operating voltage of PV systems. Although PID tests are currently standard tests, the expansion of floating PV power plants and installation in humid climates show that PID-free modules are still sensitive to this type of degradation. Therefore, a method that can detect PID in the initial phase before standard tests reveal it, is necessary to increase the reliability of PV systems and maintain their lifetime. One possible tool for revealing early-stage PID manifestations is impedance spectroscopy and I-V dark curves measurements. Both IS and dark current measurement methods are sensitive to cell shunt resistance (RSH), which is strongly influenced by PID before significant power loss and can act as an early stage PID detection mechanism. The paper describes the differences of the common P-type PV module parameters both during the degradation process and also during the regeneration process when diagnosed by conventional and IS and dark current measurement methods.

Understanding Photovoltaic Module Degradation: An Overview of Critical Factors, Models, and Reliability Enhancement Methods

“…However, models are often constrained to specific parameters, limiting applicability across different environments and technologies [41]. Key factors influencing PV degradation encompass weather variations, materials quality, design parameters, PID susceptibility, and hot spots [26][27][28][29][30][51][52][53][54][55][56]. Strategies like protective coatings, encapsulation enhancements, and cleaning help mitigate degradation and prolong lifespan [51][52][53][54][55][56].…”

“…Key factors influencing PV degradation encompass weather variations, materials quality, design parameters, PID susceptibility, and hot spots [26][27][28][29][30][51][52][53][54][55][56]. Strategies like protective coatings, encapsulation enhancements, and cleaning help mitigate degradation and prolong lifespan [51][52][53][54][55][56]. A holistic understanding of interdependent degradation mechanisms is essential for performance improvements [57][58][59][60].…”

“…Indoor and outdoor testing under STC enables standardized comparison [8,10,29]. -temperature coefficient of voltage; Rs -series resistance; Imeas -measured current; Vmeasmeasured voltage; Vt -module thermal voltage 53]. These parameters enable modeling PV performance under variable real-world operating conditions based on STC reference benchmarks.…”

“…Inability to thoroughly analyze degradation phenomena. [11,53] The linear degradation model describes the gradual deterioration of a material or component over time. It assumes degradation occurs at a steady, constant rate that is linearly proportional to the length of exposure.…”

Behavioral Analysis of Potential Induced Degradation on Photovoltaic Cells, Regeneration and Artificial Creation

“…Another method for solving the PID phenomenon is the biasing of the PV cells with a high voltage, with a polarity opposite to the voltage causing the phenomenon. Specifically, a high voltage can be applied between the cell and the frame [16] or by using corona discharge [10,17]. Commercial products, such as in [18][19][20], apply high voltage to PV panels to deal with PID problems that already exist, but the complexity of their power conversion stage is unknown.…”