Reliability Of PV Systems Research Articles

Innovative solar PV array design: mitigating partial shading for Optimal Performance Index

Photovoltaic arrays are popular for green energy but suffer productivity loss from module faults and partial shading conditions (PSC). These two faults must be distinguished to avoid a permanent shutdown. Hence, this article presents two Novel 4 X 4 array structures with fewer tie-lines to address mismatch power loss under these abnormal conditions. The performances of these novel arrays are compared with Total-Cross-Tied (TCT), Honey-Comb (HC), and Bridge-Link (BL) under three PSC categories, with six cases falling into each category. PSCs are analysed at constant and varying temperatures, along with row and column module faults. Thirteen performance indices, including the Overall Performance Index (OPI), are addressed. The percentage reduction of tie-lines in novel topologies, along with their strengths and limitations, and variation of the performance indices of all the topologies are analysed. The obtained results reveal that the Novel-1 and Novel-2 arrays capture the global maximum power point (GMPP) in 67% and 78% of the analysed situations, respectively, outperforming standard arrangements and decreasing tie-lines. These findings support the efficacy and economic benefits of the novel array configurations, which provide considerable increases in PV system performance and reliability across a variety of environmental circumstances.

Thermal Image and Inverter Data Analysis for Fault Detection and Diagnosis of PV Systems

The world’s energy demand is on the rise, leading to an increased focus on renewable energy options due to global warming and rising emissions from fossil fuels. To effectively monitor and maintain these renewable energy systems connected to electrical grids, efficient methods are needed. Early detection of PV faults is vital for enhancing the efficiency, reliability, and safety of PV systems. Thermal imaging emerges as an efficient and effective technique for inspection. On the other hand, evidence indicates that monitoring inverters within a solar energy farm reduces maintenance expenses and boosts production. Optimizing the efficiency of solar energy farms necessitates comprehensive analytics and data on every inverter, encompassing voltage, current, temperature, and power. In this study, our objective was to perform two distinct fault analyses utilizing image processing techniques with thermal images and machine learning techniques using inverter and other physical data. The results show that hotspot and bypass failures on the panels can be detected successfully using these methods.

Long-term reliability of photovoltaic c-Si modules – A detailed assessment based on the first Italian BIPV project

Assessing the long-term reliability of PV systems is important for understanding their energy and cost efficiency. Typically, estimates and predictions are based on indoor tests and accelerated ageing. However, fluctuating and differently interacting outdoor factors such as solar radiation, dust, and shadowing in real environment can impact the actual performance. This paper examines alterations related to ageing of c-Si PV modules, firstly by classifying the main factors that affect aged c-Si PV modules and then assessing the impact on their performance degradation by analysing a pilot BIPV system at Politecnico di Milano after 20 years of actual operation. Such system, which is highly representative since is the first public BIPV plant funded in Italy, was carefully and continuously monitored during its operating life. In particular, according to the visual/IR inspection carried out after the 20th year of operation, the main observed alteration in the modules were discoloration of the encapsulant, delamination, and chalking of the backsheet. The I-V characterization shown that all sampled modules had an overall degradation rate of less than 20 %, which is within the warranty limit, although in many cases the degradation rate over time shows a non-linear trend. Only one module experienced a severe fault that caused the complete loss of functionality. Obtained results confirm the reliability of c-Si technology, stressing the importance of a careful monitoring especially after the 15th year, when an increase of the degradation rate might occur.

A Modified Bypass Circuit for Improved Reliability of PV Module Validated With Real-Time Data

Solar Power is a promising way of electricity generation but it comes with a drawback of low conversion efficiency which is caused by several factors, the most prominent being partial shading. Partial shading leads to mismatch of PV cells, resulting in formation of hot spot. This leads to power dissipation and physical damage to PV cells. Consequently, panel’s credibility is called into question. A bypass diode reduces the amount of power dissipated by a shaded cell, but it doesn’t entirely prevent hot spot formation. Moreover, bypass diode doesn’t bypass every small shade as it has a shaded area threshold at and above which it begins to bypass the shaded module. Whereas, the rise in temperature may also be triggered even by a small shaded area, like the area of falling leaves, which further creates reliability issues. A few hot spot mitigation strategies have been devised; however, it still has room for improvement. This paper presents a modified bypass circuit arrangement for reliability enhancement of PV systems and it is evaluated for a 3×1 PV string. A comparative analysis with bypass diode is carried out in an experimental study. The efficacy of the proposed methodology is verified based on four performance metrics, namely reverse voltage, power loss under partial shading, the sensitivity of the bypass circuit, and the temperature of the hot spotted module. The proposed technique ensures sensitivity enhancement of the bypass circuit towards shade effect; thus, enhancing the reliability of PV system.

Performance and Reliability Analysis of Double Boost Converter Fed Renewable PV System

The article gives the performance and reliability analysis of renewable PV systems fed with a double boost converter. For analyzing the PV system performance and reliability, a 660 W PV system is considered and a double boost converter with the PSO MPPT method is implemented by adding a secondary path to the conventional boost converter, which shares the input current and reduces the current ripples in the system. For a detailed analysis of the system, different solar irradiations of 1000 W/m2, variable irradiations, and real-time solar irradiation in the area of 13039129.311N 79029109.311E on May 2022 are considered and reliability indices are presented at PV system and power electronic converter components. A MATLAB/Simulink environment is chosen for analysis of the proposed system in different conditions.

Photovoltaic Module Degradation Forecast Models for Onshore and Offshore Floating Systems

The degradation trend of photovoltaic modules depends on the technology, manufacturing techniques and climatic conditions of the site where they are installed. Longer useful life of the PV modules means that they will be able to produce much more energy than was used to build them; thus, extending the useful life of the modules is beneficial for the environment and increases the cost effectiveness of PVs. The problem of land use has prompted the development of agrivoltaic systems to exploit the same land both for the production of energy and for agriculture, and on water surfaces such as lakes and dams (floating PV). The exploitation of floating PV systems in onshore and offshore areas is currently under study. This constitutes an opportunity for which many factors must be taken into account; a fundamental aspect is the environmental impact, on which some recent studies have focused. Another aspect is the impact of the marine environment on PV system reliability and durability, due to the stress on operating conditions. The aim of this preliminary study is to evaluate the influence of the marine environment on the degradation trend of photovoltaic modules, based on existing models whose inputs are meteorological data from offshore locations. The results obtained from the application of a cumulative exposure model unexpectedly showed a lower degradation value in the offshore environment than on the mainland: −0.95% and −3% values of power decay, respectively. The absolute value of power decay in the onshore case is higher than the typical values because the used model has to be revised, as the empirical coefficients of the model have to be calculated according to the installation environment. The empirical coefficients used in the model were obtained in environmental conditions different from those under study. In the offshore case, the degradation estimated by the model does not take into account some environmental factors typical of the marine environment. Model adaptations calibrated with datasets of plants in environmental conditions similar to those analyzed would allow for greater accuracy in the results.

Temporal Resolution of Input Weather Data Strongly Affects an Off-Grid PV System Layout and Reliability

Renewable energy systems design using average year weather data is a standard approach that works well for grid-tied systems, but for stand-alone ones, it leads to dramatic mistakes. We considered the effect of meteorological data temporal resolution (5, 10, 15, 20, 30 min; 1, 2, 3, 4 h) on a stand-alone hybrid system’s layout in terms of equipment cost, power supply reliability and maximum duration of interruption for monitoring equipment in the Alps. We have shown that lifecycle costs could be strongly (order of magnitude) underestimated for off-grid systems, as well as their reliability overestimated. Lower temporal resolution data lead to the underestimation of energy storage charge–discharge cycles (considering depth of discharge too)—real batteries are to be replaced more often, which matches our practical experience as well. Even a 5 to 10 min decrease in weather data temporal resolution leads to the estimated annual expenses being halved. In general, we recommend using 30 min. resolution.

LED Lighting Agrosystem with Parallel Power Supply from Photovoltaic Modules and a Power Grid

The paper considers the operation of an LED lighting system with a parallel power supply from photovoltaic modules and a power grid. Such systems are supposed to be widely applicable in premises with limited natural lighting, particularly agrosystems where artificial light of a certain spectrum is specifically required to ensure efficient plant growth. The paper presents the scheme of the developed LED lighting system, as well as an assembled prototype containing a single 36-watt lamp. The data of the experimental study are provided on the developed LED lighting system using the developed monitoring system. The experimental study demonstrates an efficient power take-off and the reliability of the proposed scheme to competently select the characteristics and circuit solutions for the converter of voltage from the PV module. The proposed LED system allows simplification of the PV system by eliminating circuits with an inverter and storage devices, hence significantly reducing the cost of the photovoltaic systems. Likewise, such a simplicity has a positive effect on PV system reliability, which benefits the cost as well.

Reliability analysis of PV generating systems in the islanded DC microgrid under dynamic and transient operation

Dynamic fluctuations in the PV-source power and different DC-fault scenarios in the off-grid PV-battery-based DC microgrid could lead to a rapid decrease in the reliability of the PV-generating system. To make this viewpoint clearer, this paper proposes a novel reliability-evaluating methodology for PV-generating systems in the islanded DC microgrid under dynamic and transient operation conditions. Firstly, the dynamic-voltage-varying failure rate (DVVFR) and the fault-current-varying failure rate (FCVFR) of a PV-generating system in the off-grid DC microgrid are formulated. The DVVFR mainly depends on dynamic fluctuations in the PV-source power and the load power, whereas the FCVFR mostly represents the failure probability due to pole-to-pole and pole-to-ground faults in the DC microgrid. Then, a possible combination of the used-time-varying failure rate (TVFR), the power-loss and temperature-dependent failure rate, the DVVFR, and the FCVFR is proposed for evaluating the system-level and component-level reliability of PV-generating sources. Finally, Markov-state transition diagrams and Chapman–Kolmogorov equations are derived and applied for the PV-system reliability assessment in the off-grid PV-battery-based DC microgrid. Experimental results are analysed to reveal that the operation of DC-DC power converters dominates the PV-system reliability under the dynamic and transient operation. The DVVFR of the PV system is mostly smaller than its FCVFR, however, the system-level reliability of the PV-generating source is significantly reduced by dynamic-voltage-fluctuating cases due to the more frequent repetition of these dynamic cases. Moreover, the MTTF and MTBF of the PV-generating system could also be dramatically decreased by the dynamic and transient operation of the DC microgrid.

Forword Special Issue: “Best Papers From the 2021 IEEE Photovoltaic Specialists Conference”

The IEEE Photovoltaic Specialists Conference (PVSC) is the leading venue for presentation of the latest results on PV materials and devices. The conference focuses on the following 12 topical areas: 1) fundamentals and new concepts for future technologies; 2) chalcogenide thin film solar cells; 3) high-efficiency multijunction and concentrator technologies; 4) silicon photovoltaic materials and devices; 5) characterization methods; 6) perovskite and organic materials and solar cells; 7) space and specialty technologies; 8) PV modules, manufacturing, systems, and applications; 9) PV module and system reliability; 10) power electronics and grid integration; 11) solar resource for PV and forecasting; 12) PV deployment, policy, and sustainability. This year, for the first time, the program committee was asked to invite authors of particularly important or interesting contributions to submit their work to the IEEE JOURNAL OF PHOTOVOLTAICS in place of publishing in the conference proceedings. A total of 73 articles were invited to contribute manuscripts and 29 were submitted to the journal. A total of 23 of these have been accepted for publication and are included in a Special Issue of the journal. Accepted articles include topics from areas 2), 4), 5), 8), 9), 11), and 12) from the abovementioned list.

Control-Oriented Model of Photovoltaic Systems Based on a Dual Active Bridge Converter

Solar energy is a source of sustainable energy and its optimal use depends on the efficiency and reliability of PV systems. Dual active bridge converters are a solution to interface PV modules with the grid or high voltage requirement applications due to the high voltage-conversion-ratio and high efficiency provided by such a converter. The three main contributions of this work are: an extensive mathematical model of a DAB converter connected to a PV module including protection diodes, which is intended to design non-linear controllers, an explicit linearized version of the model, which is oriented to design traditional control systems; and a detailed and replicable application example of the model focused on maximizing the power extraction from a PV system. The modeling approach starts with the differential equations of the PV system; however, only the fundamental and average components of each signal is used to represent it. The control-oriented model is validated using a detailed circuital simulation. First, through the comparison of frequency and time diagrams of the proposed model and a detailed one; and then, through the simulation of the PV system in a realistic application case. PV voltage regulation and maximum power extraction are confirmed in simulation results.

Modeling of Photovoltaic Modules Under Common Shading Conditions

Common shading conditions will leads to power loss and even result in hotspots, which influence the reliability of PV systems. Therefore, it is necessary to model for PV modules under common shading conditions in the PV station. Modeling of the shaded module relies on the appropriate model for the (partial) shaded cell. We observe that shaded region and unshaded region in a PV cell work quite differently. In the shaded region, the photoinduced current will decrease, and the shunt resistance will increase. In the unshaded region, the temperature rise can be even higher than 100 ℃. Consequently, it is essential to model for the shaded region and unshaded region respectively. In this paper, a physically explicable parallel model is proposed for the shaded cell and modeling of PV modules under common shading conditions are studied. We conduct extensive experiments, shading PV modules by area-measurable shade cloth with regular shape to analyze their I-V characteristics. PV modules are also shaded by uniformly accumulated dust, and leaf / soil / shadow with arbitrary shape and location to simulate the situation in real PV station. Experimental results verify the effectiveness of our method.

Capacity Factor Analysis of U.S. PV System Reliability and Performance

We present an evaluation of the ac capacity factor to estimate the reliability and performance trends of existing plants in the United States. The capacity factor is a metric that is widely used in the electrical power sector to estimate operational consistency. We show that the ac capacity factor provides useful insight to assess the system productivity. We analyze U.S. Energy Information Administration data for more than 2300 plants, showing that both ac capacity factor and inverter-loading ratios have increased in recent years, and that the capacity factor tends to increase for larger systems and increases as would be expected for mounting configurations and locations associated with high insolation. Evaluation of the data for reliable (consistent) performance concludes that inconsistent operation causes much more variation in reported electricity generation than linear degradation.

Fault diagnosis of PV array using adaptive network based fuzzy inference system

A new online intelligent fault diagnosis method is proposed for PV arrays in this paper to improve the reliability and efficiency of PV systems. Firstly, a new seven-dimensional fault feature vector is extracted from the raw data of dynamic operating points of PV arrays including operating voltage, current, irradiance and temperature. Secondly, an optimized adaptive network based fuzzy inference system (ANFIS) is proposed as the fault diagnosis model. Lastly, the feasibility and superiority of the proposed ANFIS based fault diagnosis model are tested by both Simulink based simulation and real fault experiments on a laboratory PV system. Experimental results validate that the proposed ANFIS based method achieves a high performance and is superior to conventional back-propagation neural network (BPNN) based methods. The overall accuracy of the ANFIS based fault diagnosis model on the simulation and experimental dataset is 99.9% and over 97% respectively.

Design for reliability of multifunctional PV inverters used in industrial power factor regulation

Industrial consumers are widely known for their high demand for active and reactive power. Thus, these consumers have a great interest in the local generation using PV plants to reduce the energy bill. However, the traditional PV systems reduce the active power absorbed from the grid and, consequently, the installation power factor. Under such conditions, fees are being charged due to the low facility power factor. This work carries out an overall study on the effects of the installation of a PV plant on the industrial power factor. Moreover, solutions based on traditional capacitor banks or multifunctional PV inverters are benchmarked. The case study of an industrial power plant located in Brazil is discussed. The results indicate that the traditional capacitor bank solution cannot correct the power factor all time due to its limited number of taps. Nevertheless, the multifunctional PV inverter can provide a precise reactive power compensation, which improves the power factor and eliminates the additional fees. However, a PV system reliability reduction of 24.1% is observed compared to the traditional operation, while inverter oversizing preserves the system reliability even by correcting power factor.

Economic Performance of Net-Zero Energy Community under Reward-Penalty Mechanism Considering PV System Reliability

Abstract Economic performance of net-zero energy building/community (ZEB/ZEC) is an important factor that affects potential investors’ decision on installing renewable energy systems (RES). A reward-penalty mechanism (RPM) is proposed for accelerating the development of zero energy communities, which is developed without considering the reliability effect from RES generation. However, an investigation is deserved for the reliability effect of RES on building economic performance. A case study is therefore conducted based on an assumed community consisting of 20 family houses, in which the electricity load was collected by the smart meter for more than one year. The results show that the proposed RPM works efficiently under an ideal condition, while the costs of the community and its buildings are greatly increased when the effect of PV system reliability is considered. Specifically, the total cost of the community under 1.0ZEC design is 5 005 USD/yr in the first year, which increases to 11 341 USD/yr in the 25th year. By contrast, the total cost of the community under 1.2ZEC design is 5 243 USD/yr in the first year and increases to 9 607 USD/yr in the 25th year. It is believed that the results of this study can provide a progressive perspective for scheme makers and building owners in terms of its economic benefit. Development of enhanced RPM by considering system reliability will be investigated in our future work.

An overview of methods used for outdoor performance characterization of photovoltaic module string upto 10 kWp

Solar photovoltaic (SPV) energy is most promising among renewable energy (RE) sources. Outdoor performance characterisation of SPV module string using on-field test equipment with a minimum error by reducing the effect of an uncertain operating condition (OPC) is challenging. Improving PV system reliability, flexibility and reducing operation and maintenance (O&M) cost have become a significant factor in increasing the competitiveness of the PV energy market. An illustrative embodiment of literature described herein is particularly suited to select load for current-voltage curve tracer (IVCT) for varying complexities from SPV cell (few Watts) to SPV module string (up to 10 kWp).

Reliability model assessment of grid-connected solar photovoltaic system based on Monte-Carlo

The rapid growth of photovoltaic PV energy utilization and the immense potential for future use dictate a need to seriously consider the reliability of PV system. In this study, the comprehensive model to assess the reliability of large-scale and grid-connected PV system was proposed, taking account of weather condition as well as critical component failure probability. In addition, the sequential Monte-Carlo simulation was also established, combining with the developed model. And this analytical approach was successfully applied to evaluate the practical PV system in western area of China. The result showed that the reliability increased as the system capacity increased. And the simulated value become more accurate when the basic model was modified by more factors, especially by weather condition. While for the fixed-capacity system, the reliability decreased periodically as the operation time prolonged, which was mainly caused by the PV modules and inverters failure probability.

Study of the Reliability of Static Converter for Photovoltaic Application

The study of the reliability of PV systems, although they are answered in the world, is rare. In Algeria we have recorded any university research laboratory on the subject, despite the government gives great importance to the development of PV systems from us. It is therefore important to know the reliability, availability and sustainability of these systems. This will help to objectively determine the lifetime of a PV system before the costs become more important than the gains from the system.The objective of this work is to calculate the reliability of the MPPT of PV system and simulate the combination of a photovoltaic panel with a DC/DC converter controlled by the technical Disrupts & Regards. Two choppers are available for study parallel (three conduction modes and three powers), and the chopper Cuk (for the same power).

A PV power supply module for a portable Cubesat satellite ground station

This research focuses on the problem of powering a remote and mobile satellite ground station, where utility power is unavailable. It focuses on the use of photovoltaic energy, which is now widely accepted as an alternative source of energy. However, PV suffers from low conversion efficiency, non-linear I-V characteristics, which depend on temperature changes and the earth rotation. The research focuses on accurate determination of the ground station power budget whose total power demand involves an azimuth and rotator function and a current which varies depending on the stages of communication with the satellite. The power budget is used to determine the size, the ratings of solar generators, batteries and the system components. With the aid of a power logger, the PV voltage, the battery voltage, the AC voltage and PV power output is analysed for varying satellite loads. The data is analysed by taking into account the solar irradiation level on the day of measurement and the percentage cloud cover. This method is found to improve the reliability and can be adopted to improve reliability of standalone PV systems. The results are vital in PV power management and design.