Diagnostics of PID Early Stage in PV Systems

Tomáš Finsterle,Ladislava Černá,Pavel Hrzina,Vítězslav Benda,David Rokusek

doi:10.3390/en14082155

Tomáš Finsterle, Ladislava Černá + Show 3 more

Open Access

https://doi.org/10.3390/en14082155

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Journal: Energies	Publication Date: Apr 13, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: Czech Technical University in Prague

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.

Highlights

The potential induced degradation (PID) is one serious problem of present PV plants.The impact of the PID on the power plant can be very significant, because PV modules can lose up to 70% of their original performance in real conditions due to PID
This paper focuses on the comparison of the sensitivity of PID detection using several diagnostic methods during the process of parameter degradation and subsequent regeneration using the opposite polarization of the applied voltage
PID andonly subsequent regenerhysteresis and did not return to the original value. This degradation of the ation, it was found that the shunt resistance RSH is most sensitive to the incipient PID

Summary

Introduction

The impact of the PID on the power plant can be very significant, because PV modules can lose up to 70% of their original performance in real conditions due to PID. The basic prerequisite for the progression of PID is a high potential difference between the module and the ground. The existence of high voltage stress on modules was first raised in 1978 by Hoffman and Ross of the Jet Propulsion Laboratory in a study on real-life testing [2]. The performance of PV modules decreases rapidly during laboratory testing, due to the use of accelerated conditions such as higher voltage or humidity. If PV modules work in the field and are subject to PID, their performance may deteriorate slowly and over a long period (more than a year) and the degradation process may remain undetected for a long time. Conventional methods for detecting field energy losses have combined measurement uncertainties greater than 5%, which complicates PID detection [3]

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Conclusion