Potential-induced degradation in photovoltaic modules: a critical review

Luo, Wei; Khoo, Yong Sheng; Hacke, Peter; Naumann, Volker; Lausch, Dominik; Harvey, Steven P.; Singh, Jai Prakash; Chai, Jing; Wang, Yan; Aberle, Armin G.; Ramakrishna, Seeram

doi:10.1039/c6ee02271e

Cited by 363 publications

(263 citation statements)

References 73 publications

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“…The reasons leading to PID degradation, as well as potential mitigating strategies, are multiple and interdependent . These are related to the following: The specific climatic conditions of the installation site; The electrical layout (ie, mostly the grounding and polarity) of the PV array/string; The inverter choice ; Module design aspects specific to the mounting solution (ie, the presence/absence of a frame or of back rails); Module design aspects specific to the materials (encapsulants, solar cells, glass, backsheet [BS], etc.)…”

Section: Introductionmentioning

confidence: 99%

One‐type‐fits‐all‐systems: Strategies for preventing potential‐induced degradation in crystalline silicon solar photovoltaic modules

Virtuani

Annigoni

Ballif

2018

Progress in Photovoltaics

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In this work, we investigate the relationship between potential‐induced degradation (PID) and the bill of material used in module manufacturing. We manufacture samples with different combination of materials, using two types of solar cells (conventional vs PID‐free c‐Si cells), two types of ethylene‐vinyl acetate (EVA) films with low/high resistivity, and two types of backsheets with, respectively, low/high breathability properties, and subject the mini‐modules to extended PID testing. Our results clearly indicate that, when using a breathable polymeric backsheet, to have a “PID‐free” module the combination of PID‐free cells and high‐resistive EVA encapsulants is recommendable. The use of a conventional c‐Si cell in combination with a high‐resistive EVA encapsulant is still more effective than the use of PID‐free cells in combination with low‐quality EVA. Further, our results initially show that the breathability properties of the backsheet have apparently no influence on PID degradation. A second set of experiments using sandwich structures with increased resistance properties to water ingress (ie, glass and backsheets with barrier layers as rear covers and an edge sealant), however, indicates that preventing or reducing the diffusion of moisture in the encapsulant layer plays a role in further mitigating the impact of PID. This finding is supported by simulations of moisture ingress in the sandwich structures. Finally, we show that the use of a glass rear cover—compared with a polymeric backsheet—does not contribute in worsening the PID effect. On the contrary, by reducing moisture ingress in the front encapsulant layer, it delays the occurrence of PID.

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Section: Introductionmentioning

confidence: 99%

One‐type‐fits‐all‐systems: Strategies for preventing potential‐induced degradation in crystalline silicon solar photovoltaic modules

Virtuani

Annigoni

Ballif

2018

Progress in Photovoltaics

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“…For example, by applying the method proposed in Trupke et al, Peike et al have successfully deduced the degree and spatial distribution of metal finger corrosion in silicon solar cells based on electroluminescence and photoluminescence images Material characterization techniques have also been used to study the fundamental mechanisms underlying PV degradation processes (eg, sodium migration of potential‐induced degradation (PID) via transmission electron microscopy and energy‐dispersive X‐ray spectroscopy). The Suns‐Voc method monitors the open‐circuit voltage while manually varying illumination intensity of a solar simulator (see Figure ) . Jordan et al have applied this method to extract photocarrier lifetime and series resistance of degraded solar modules .…”

Section: Introductionmentioning

confidence: 99%

Real‐time monitoring and diagnosis of photovoltaic system degradation only using maximum power point—the Suns‐Vmp method

Sun

Chavali

Alam

2018

Progress in Photovoltaics

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The uncertainties associated with technology‐specific and geography‐specific degradation rates make it difficult to calculate the levelized cost of energy, and thus the economic viability of solar energy. In this regard, millions of fielded photovoltaic modules may serve as a global testbed, where we can interpret the routinely collected time series maximum power point (MPP) data to assess the time‐dependent “health” of solar modules. The existing characterization methods, however, cannot effectively mine/decode these datasets to identify various degradation pathways. In this paper, we propose a new methodology called the Suns‐Vmp method, which offers a simple yet powerful approach to monitoring and diagnosing time‐dependent degradation of solar modules by using the MPP data. The algorithm reconstructs “IV” curves by using the natural illumination‐dependent and temperature‐dependent daily MPP characteristics as constraints to fit physics‐based circuit models. These synthetic IV characteristics are then used to determine the time‐dependent evolution of circuit parameters (eg, series resistance), which in turn allows one to deduce the dominant degradation modes (eg, solder bond failure) of solar modules. The proposed method has been applied to a test facility at the National Renewable Energy Laboratory. Our analysis indicates that the solar modules degraded at a rate of ~0.7%/year because of discoloration and weakened solder bonds. These conclusions are validated by independent outdoor IV measurements and on‐site imaging characterization. Integrated with physics‐based degradation models or machine learning algorithms, the method can also serve to predict the lifetime of photovoltaic systems.

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“…In most photovoltaic systems without a grounding system, the modules have a non-zero voltage that provokes this effect. Negative voltages are more frequently reported, especially under high voltage conditions, high ambient humidity and/or high ambient temperatures [26].…”

Section: Potential Induced Degradationmentioning

confidence: 99%

Development of a GIS Tool for High Precision PV Degradation Monitoring and Supervision: Feasibility Analysis in Large and Small PV Plants

et al. 2017

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Abstract:It is well known that working photovoltaic (PV) plants show several maintenance needs due to wiring and module degradation, mismatches, dust, and PV cell defects and faults. There are a wide range of theoretical studies as well as some laboratory tests that show how these circumstances may affect the PV production. Thus, it is mandatory to evaluate the whole PV plant performance and, then, its payback time, profitability, and environmental impact or carbon footprint. However, very few studies include a systematic procedure to quantify and supervise the real degradation effects and fault impacts on the field. In this paper, the authors first conducted a brief review of the most frequent PV faults and the degradation that can be found under real conditions of operation of PV plants. Then, they proposed and developed an innovative Geographic Information System (GIS) application to locate and supervise them. The designed tool was applied to both a large PV plant of 108 kWp and a small PV plant of 9 kWp installed on a home rooftop. For the large PV plant, 24 strings of PV modules were modelized and introduced into the GIS application and every module in the power plant was studied including voltage, current, power, series and parallel resistances, fill factor, normalized PV curve to standard test conditions (STC), thermography and visual analysis. For the small PV installation three strings of PV panels were studied identically. It must be noted that PV modules in this case included power optimizers. The precision of the study enabled the researchers to locate and supervise up to a third part of every PV cell in the system, which can be adequately georeferenced. The developed tool allows both the researchers and the investors to increase control of the PV plant performance, to lead to better planning of maintenance actuations, and to evaluate several PV module replacement strategies in a preventive maintenance program. The PV faults found include hot spots, snail tracks, ethylene vinyl acetate (EVA) discoloration, PV cell fractures, busbar discoloration, bubbles and Si discoloration.

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Potential-induced degradation in photovoltaic modules: a critical review

Abstract: This paper presents a critical review on potential-induced degradation (PID) in photovoltaic modules to illustrate the current research status and potential research paths to address PID-related issues.

Cited by 363 publications

References 73 publications

One‐type‐fits‐all‐systems: Strategies for preventing potential‐induced degradation in crystalline silicon solar photovoltaic modules

One‐type‐fits‐all‐systems: Strategies for preventing potential‐induced degradation in crystalline silicon solar photovoltaic modules

Real‐time monitoring and diagnosis of photovoltaic system degradation only using maximum power point—the Suns‐Vmp method

Development of a GIS Tool for High Precision PV Degradation Monitoring and Supervision: Feasibility Analysis in Large and Small PV Plants

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