Experimental analysis of the effects of potential-induced degradation on photovoltaic module performance parameters

Monitoring of Photovoltaic System Performance Using Outdoor Suns-VOC

Potential Induced Degradation (PID) is one of the most important factors effecting the performances of Photovoltaic (PV) modules and PV systems in recent years. In this paper the PID phenomena of the PV power plant in different typical climate regions were studied and some experimental PID simulations were carried out in order to find out the factors effecting the performance by PID. The results show that the typical PID phenomena are easy to occur in cells close to the border of the PV module. PID phenomena can appear in PV power plants under different climate conditions, but the effecting degrees on module performance are different depending on temperature, humidity and other parameters. We also find the maximum power would recover in some degree after positive-bias voltage duration.

n‐Type crystalline‐silicon (c‐Si) photovoltaic (PV) cell modules attract attention because of their potential for achieving high efficiencies. The market share of n‐type c‐Si PV modules is expected to increase considerably, with wide use in PV systems, including large‐scale PV systems, for which the system bias is set as markedly high. Such a high system bias leads to performance losses known as potential‐induced degradation (PID). By virtue of many researchers’ efforts, the PID behaviors, mechanisms, and preventive measures against PID have been well documented in conventional p‐type c‐Si modules. Researchers recently started to investigate PID in high‐efficiency c‐Si solar cells including n‐type c‐Si PV modules. Yet, the understanding of PID phenomena remains incomplete. Herein, a literature review of PID in high‐efficiency n‐type c‐Si PV modules is provided as a resource elucidating the current status of related research and remaining unresolved issues. This report mainly presents discussion of PID in several kinds of n‐type c‐Si PV modules in terms of materials science. PID phenomena are described as divided into some degradation modes. Details present a review of their respective degradation modes, degradation behaviors, proposed mechanisms, and potential measures against degradation. Remaining open issues and anticipated future studies are also summarized.

In the potential induced degradation (PID) phenomenon, the output power of a photovoltaic (PV) module decreases due to the high potential difference between the PV system and the ground. This voltage forcefully moves the positive charge in the module to the surface of the solar cell. The accumulated charge leads to the performance deterioration of the module, namely, PID of the module. We conducted a study to accurately predict the output reduction of the module operating in various installation conditions coming from the PID phenomenon. We investigated the leakage current flowing through front glass laminated with encapsulation material simultaneously exposed to various performance conditions of the PV system, namely, relative humidity, temperature, and applied voltage, which have an important effect on the PID of the module. The degradation of the module coming from PID was calculated on the basis of the obtained leakage current. To confirm the calculated data, modules with one solar cell were manufactured and the power loss results of the modules' exposure to various PID generation experiments were compared with the expected results. The results showed that we could predict the degradation of the modules by PID within a 2% tolerance under the PV system installation conditions.

Quality, reliability, and durability are the key features of photovoltaic (PV) solar system design, production, and operation. They are considered when manufacturing every cell and designing the entire system. Achieving these key features ensures that the PV solar system performs satisfactorily and offers years of trouble-free operation, even in adverse conditions. In each cell, the quality of the raw material should meet the quality standards. The fulfillment of the quality management system requires every part that goes into the PV solar system to undergo extensive testing in laboratories and environments to ensure it meets expectations. Hence, every MWh of electricity generated by the PV solar system is counted, the losses should be examined, and the PV system’s returns should be maximized. There are many types of losses in the PV solar system; these losses are identified and quantified based on knowledge and experience. They can be classified into two major blocks: optical and electrical losses. The optical losses include, but are not limited to, partial shading losses, far shading losses, near shading losses, incident angle modifier (IAM) losses, soiling losses, potential induced degradation (PID) losses, temperature losses, light-induced degradation (LID) losses, PV yearly degradation losses, array mismatch losses, and module quality losses. In addition, there are cable losses inside the PV solar power system, inverter losses, transformer losses, and transmission line losses. Thus, this work reviews the losses in the PV solar system in general and the 103 MWp grid-tied Al Quweira PV power plant/Aqaba, mainly using PVsyst software. The annual performance ratio (PR) is 79.5%, and the efficiency (η) under standard test conditions (STC) is 16.49%. The normalized production is 4.64 kWh/kWp/day, the array loss is 1.69 kWh/kWp/day, and the system loss is 0.18 kWh/kWp/day. Understanding factors that impact the PV system production losses is the key to obtaining an accurate production estimation. It enhances the annual energy and yield generated from the power plant. This review benefits investors, energy professionals, manufacturers, installers, and project developers by allowing them to maximize energy generation from PV solar systems and increase the number of solar irradiation incidents on PV modules.

Photovoltaic (PV) systems can be affected by different types of defects, faults, and mismatching conditions. A severe problem in PV systems has arisen in the last couple of years, known as potential-induced degradation (PID). During the early installation stage of the PV system, the PID may not be noticed because it appears over time (months or years). As time passes, it becomes more apparent since the output power may drop dramatically. We studied PV modules over the course of three years that were affected by PID. An electroluminescent and thermal imaging technique helped discover the PID. PID appeared in PV modules after being in different fields for 4–8 months, resulting in a 27–39% drop in power. An anti-PID box was fitted during the second year of the PV operation to recover the PID. Accordingly, it has stabilized the power degradation, but it could not restore the performance of the affected PID modules as compared with healthy/non-PID modules.

Potential induced degradation in c-Si glass-glass modules after extended damp heat stress

Potential Induced Degradation (PID) is expected to become more frequent with the increased system voltage of photovoltaic (PV) systems. Thus, a PID detection method is required to detect PID at an early stage in order to increase the reliability of PV systems and the lifetime of PV modules. In this paper, a relation between the shunt resistance and the power loss of a PV cell due to PID is derived for the development of a detection model from cell to module level. The results indicate a logarithmic relationship. In addition, a shunt resistance threshold, at which significant power loss starts to appear, is derived. The threshold is examined for various power loss levels and temperatures. The threshold was found to decrease with temperature with a near linear behaviour.

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.

The photovoltaic (PV) array performance is significantly affected by solar irradiation, temperature and its configuration. Indeed, the array configuration has an impact to modify the series (Rs) and the shunt (Rsh) resistances that appear in its mathematical model. Moreover these resistances are dependent on temperature variation. Hence, the latter can affect I-V and P-V characteristics by modifying the Rs and Rsh resistances. Consequently, the maximum power point (MPP) can be shifted and thus the efficiency and reliability of the entire PV system can be affected. This paper is based on modeling and simulation of the I-V and P-V characteristics of a PV array under non uniform temperature that influences the series and shunt resistances. Simulation results show that, compared to the case when temperature variation do not affect the Rs and Rsh resistances, temperature variation effect is always dominated and the resistances effects are more visible for high temperature value. However the comparison Rs and Rsh effects shows that the Rs variation effect versus temperature variation is more significant. The proposed PV array study can be used in PV system design and it permits to evaluate its performance not only under standard conditions but also under resistances variations. Indeed, it is very important to predict the PV array behavior to an effective use of a PV system under all conditions.

Impact of different backsheets and encapsulant types on potential induced degradation (PID) of silicon PV modules

Research on potential induced degradation (PID) of polymeric backsheet in PV modules after salt-mist exposure

Potential induced degradation (PID) is still a serious threat for the photovoltaic (PV) industry and it is expected to aggravate due to the tendency to increase the operating voltage of PV systems. Therefore, a method which can detect PID at an infant stage is necessary in order to increase the reliability of PV systems and preserve their lifetime. This paper provides a pathway (proof of concept) for the early and reliable detection of PID, by using the forward dc resistance (FDCR) of a PV cell since it is a parameter, which is affected by the cell's shunt resistance ( R sh), which in turn is heavily affected by PID before any significant power loss occurs, and could act as a PID detection mechanism. The paper presents simulation results, which examine at which forward bias conditions the FDCR has to be measured for the purpose of using it as a PID detection means at an early stage ( I 0), and ideality factor ( n ). Furthermore, an experiment was performed to verify the simulation results, demonstrating detection before 2% power loss occurs.

Monocrystalline silicon photovoltaic mitigation of potential-induced degradation using SiO2 thin film and + 1000 V biasing

This article addresses the investigation of alternative methods for evaluating Potential Induced Degradation (PID) in photovoltaic (PV) modules. Although PV modules are widely used in electricity generation, they are susceptible to various failure mechanisms, with PID being a notable one. Traditionally, PID detection is performed through electroluminescence analysis in a laboratory, involving the relocation of panels and additional costs. The identified methods aim to enable field evaluation, reducing both the costs involved and the losses in energy generation. This approach not only simplifies the detection process but also allows for a more prompt intervention to mitigate the detrimental effects of PID on PV systems.