Output performance analysis and power optimization of different configurations half-cell modules under partial shading

Solar photovoltaic (PV) modules are made up of with 32, 36, 48, 60, 72, and 90 number of series connected solar cells, depending on the size and maximum power output of the module. When one solar cell or group of solar cells in PV module (PVM) are partially or fully shaded, the output power gets reduced due to power mismatches, and which can also cause a hotspot heating problem in a PV modules. This research paper focuses on the development of new PV modules (based on arrangement of solar cells within a PVM) with cell-level configurations (PVM-CLC) such as series connection module (SCM), series–parallel connection module (SPCM), total cross-tied connection module (TCTCM), bridge-linked connection module (BLCM), and honey-comb connection module (HCCM) with number of bypass diodes (BDs) to minimize the partial shading effect on PV modules. For this investigation, 36 solar cells were used to develop the new 40 W PV modules. And MATLAB/Simulink software was used to analyze the performance of developed PVM in terms of global maximum peak power and mismatch losses under different cell-level shading cases/conditions. The maximum power results are obtained under considered cell-level shading cases shows that the TCTCM outperforms other cell-level configuration modules. The main objective of this study is to get more power output under shading conditions by developing new PV modules. The proposed PVM-CLC not only reduces the mismatch power loss but also makes installation easier and less complicated when compared to array configurations.KeywordsSolar PV moduleCell-level configurationsCell-level shading casesBypass diodeGlobal maximum peak powerMismatch loss

A novel electrical approach to protect PV modules under various partial shading situations

A Configuration of bypass diodes affects the performance of photovoltaic (PV) system when it is exposed to partial shading. The power-voltage (P-V) curve of shaded string has multiple power peaks (MPPs) one of them is a global maximum power (GMPP) due to the exploitation of bypass diodes. There are two configurations of bypass diodes: non-overlapped and overlapped. Almost all PV studies are based on the non-overlapped bypass diodes, the effects of the diodes are well understood. On the other hand, a complete analysis for the effects of the overlapped bypass diodes on the performance of the PV module has not been yet systematically disclosed. In this paper, mathematical equations describe the dynamic performance of the PV module with overlapping diodes under partial shading conditions are developed. The electrical characteristics of the PV module with different bypass diodes configurations are comprehensively studied under different partial shading conditions by using MATLAB Simulink.

This study investigates the impact of shading on the performance of photovoltaic (PV) systems, a critical consideration for optimizing solar energy generation. Shading can occur due to various environmental factors, including nearby structures, vegetation, and atmospheric conditions, leading to significant reductions in energy output and overall system efficiency. Through a combination of experimental measurements and simulation modeling, we assessed how different shading scenarios affect the electrical performance of PV arrays. The findings reveal that even partial shading can cause substantial decreases in power generation, with shaded cells experiencing reverse biasing and increased thermal stress, resulting in potential hot spot formation. The analysis also highlights the importance of PV module configuration and orientation in mitigating shading effects. Additionally, the study highlights the functionality of bypass diodes in PV systems. By allowing current to bypass shaded or malfunctioning cells, these diodes help maintain optimal performance levels even when some cells are compromised. The analysis includes comparative assessments of PV systems with and without bypass diodes under identical shading conditions. Results demonstrate that systems equipped with bypass diodes exhibit significantly improved performance, including higher voltage and current outputs, thereby enhancing overall energy yield. This research underscores the necessity for site-specific evaluations during the design phase of PV installations to ensure maximum efficiency. The insights gained from this study contribute to a deeper understanding of shading dynamics in PV systems and provide practical recommendations for improving solar energy utilization. Ultimately, addressing shading challenges is essential for advancing the reliability and effectiveness of solar power as a sustainable energy solution. The findings deduce the importance of integrating bypass diodes in PV systems to mitigate the detrimental effects of shading, ultimately contributing to more effective utilization of solar energy resources.

By examining the effect of ambient temperature on photovoltaic (PV) module performance in Diyala Governorate, Iraq, this research intends to optimise solar energy utilisation in the region, contributing to a more sustainable future by dropping reliance on fossil fuels. The study precisely highlights that ambient temperature has a noteworthy negative influence on PV module performance. Particularly, an increase in the temperature of the PV module leads to energy losses due to a reduction in the generated voltage. In this research, a set of experiments was accomplished to appraise the outdoor performance of a polycrystalline PV module under the actual conditions of Diyala Governorate. The energy losses of the PV module are detailed and thoroughly analysed. The findings of this research indicate that the output power and average efficiency of the PV module in summer were found to be 130.8 W and 13.6%, respectively, in a comparison to 126.5 W and 14.1% in winter. This agrees to a maximum performance ratio of 82.5% in summer at 3:00 pm and 84% in winter at 9:00 am.

The output power of photovoltaic modules is significantly reduced by solar irradiance shading. To address this issue, innovative strategies for mitigating shading effects have been continuously explored. In this study, detailed research on the edge dust accumulation effect of modules has been conducted. It is found that under vertical installation, when the shading ratio reaches 50%, the output power of full-cell modules decreases by 42%, while that of half-cell modules drops by only 27%. Moreover, when the shading ratio reaches 100%, the output power of full-cell modules declines by nearly 99%. In contrast, half-cell modules are still able to maintain nearly 50% of their output power. These results demonstrate that half-cell modules exhibit significantly better resistance to shading compared to full-cell modules. On the other hand, under a horizontal layout, power degradation for both full-cell and half-cell modules is observed to be approximately 16% when the shading ratio is 25%, and around 36% when the coverage reaches 50%. Experimental results further revealed that shading under horizontal orientation leads to a multi-peak power output profile, which poses a risk of the PV inverter being trapped in local maxima. Overall, half-cell modules demonstrated better resistance to dust-induced shading under both layouts. Based on these findings, novel module design schemes are proposed to enhance resistance to dust accumulation effects. The proposed method can effectively reduce power losses caused by edge dust-induced shading and improve the annual power generation of PV modules, thereby offering technical support for effectively enhancing the operational stability of PV power generation systems.

The operation of photovoltaic systems depends on the environmental conditions, which affect the current-voltage characteristics of photovoltaic modules and more complex structures. Under non-uniform environmental conditions - different illumination of cells within one module - the characteristics of the module can be increasingly complex. Safety bypass diodes, which are connected in parallel with the cells and protect them from overheating during partial shading, also contribute to this complexity. In order to evaluate the performance of the photovoltaic system, specifically the inverter and the algorithm for maximum power point tracking, it is necessary to take into account these influences on the characteristics of the photovoltaic structures. In this manuscript, the influence of illumination and temperature on individual photovoltaic cells, the topology of a photovoltaic module including bypass diodes, as well as the characteristics of modules with protective bypass diodes under non-uniform environmental conditions are discussed.

Flexible polymer photovoltaic modules with incorporated organic bypass diodes to address module shading effects

A maximum power point tracking technique based on bypass diode mechanism for PV arrays under partial shading

Partial shading among the photovoltaic modules is the most commonly observed scenario that can permanently damage the modules by creating mismatch among cells, hotspot, and unexpected losses in the system. Basically, modules are provided with bypass diodes for prevention from destructive effect of the hotspot. Bypass diodes configuration plays a crucial role in the operation and performance of the modules during shading. In this paper, the sensitivity of PV modules with no bypass diode, grouped bypass diodes, overlapped bypass diodes, and single bypass diodes during partial shading is investigated. The investigation is carried out in the MATLAB/Simulink environment for a module under various cell-level shadings. The comparison is done using power generation, losses, efficiency, and number of peaks analysis. It is found that the performance and characteristics of the modules are highly susceptible to the bypass diodes configurations and nature of shading.KeywordsPhotovoltaic (PV)Bypass diodesHotspotMismatch lossPartial shadingPower generation

In this work, we demonstrate that partial shading of one solar cell in a state-of-the-art monocrystalline photovoltaic module with three bypass diodes results in hot cells with critical peak temperatures of 164 $^\circ$ C. We examine two solar modules in the IEC 61215-2 MQT 09 hot-spot endurance test, one with 367.3 W $_\text{P}$ featuring 72 full-cells and the other with 388.6 W $_\text{P}$ featuring 144 half-cells. For the solar module with 72 solar cells, we measure a maximum temperature of 164 $^\circ$ C, which results in a degradation of the encapsulation material and increases the risk of solar module failure. The high temperature results from the hot cell effect due to the power dissipation in the reverse-biased solar cell caused by partial shading. Our experiments show that the half-cell solar module is advantageous in terms of solar cell shading compared to the full-cell solar module. Although the half-cell solar module has a higher power output than the full-cell solar module, we measure a cooler peak temperature of 150 $^\circ$ C. However, under certain shading conditions, the half-cell solar module can exhibit similar temperatures as the full-cell solar module. Based on our experimental results, we develop an electrical and a thermal model to predict the temperature of novel high-power solar modules with solar cells from larger silicon wafer formats in case of partial cell shading. Our predictions consider the trends of further increasing solar cell and module efficiencies, larger silicon wafer formats, and larger solar modules. We simulate a maximum peak temperature of 176 $^\circ$ C at the solar module's surface, which significantly increases the risk of solar module failure. Our results show that new high-power solar modules employing solar cells that are made from larger silicon wafer formats need a new protection against overheating. Three bypass diodes per solar module are no longer sufficient.

The power versus voltage curve of a photovoltaic (PV) panel exhibits several maximum power points (MPPs) in a partial shading (PS) condition. Thus, it remains an optimization challenge to ensure that PV systems operate at their global MPP (GMPP). Scanning the output characteristics of the PV panels seems a general solution for this issue. However, applying a short circuit to the terminal of PV panels where there exists an electrolytic capacitor, has a detrimental effect on the lifetime of the system. To this end, in this paper, a GMPP estimator is proposed as a global solution for conventional MPPT algorithms under PS conditions. The proposed technique improves existing simple MPPT algorithms with original approaches as follows: 1) An accurate microscopic analysis of a PV characteristic in PS conditions is considered; 2) an original definition of the dominant cells and modules in a PV panel is proposed that allows to reduce the PS patterns to a finite number and 3) the search area for the MPPT operation is reduced to find the accurate GMPP by proposing two voltage boundaries. The lower boundary corresponds to the GMPP under uniform shading condition that can be determined using a closed form formula, while the upper one refers to the GMPP of a dominant cell in a PV module that can be determined using an artificial intelligence technique. This can also help set the initial duty cycle in a convex area around the GMPP. The functionality of the proposed GMPP estimator is experimentally validated.

This study focuses on the partial shade-mitigating effects related to the insertion of additional ideal bypass diodes in residential-scale photovoltaic (PV) systems. For this purpose, quantification of the resulting energy yield benefits is carried out in a representative residential environment. It is widely recognized that partial shading inflicts disproportional losses to the energy output of PV systems. Increased granularity levels in cell groups are perceived as a potentially promising measure to increase the shade-tolerance of photovoltaic devices. The past years, introduction of module level electronics promise to reduce further shading losses. The developed model includes a shading evaluation of the installation with means of 3D modeling, insertion of additional by pass diodes resulting in smaller cell groups, irradiance calculations, PV cell modelling and finally an empirical power conversion model. Results suggest that in the reference case of 3 by pass diodes the micro inverter system is performing the best under partial shading. By increasing the cell group granularity the string inverter systems seems to benefit due to the wide maximum power point voltage window.

A photovoltaic (PV) module is an equipment that converts solar energy to electrical energy. A mathematical model should be presented to show the behavior of this device. The well-known single-diode and double-diode models are utilized to demonstrate the electrical behavior of the PV module. “Matlab/Simulink” is used to model and simulate the PV models because it is considered a major software for modeling, analyzing, and solving dynamic system real problems. In this work, a new modeling method based on the “Multiplexer and Functions blocks” in the "Matlab/Simulink Library" is presented. The mathematical analysis of single and double diodes is conducted on the basis of their equivalent circuits with simple modification. The corresponding equations are built in Matlab by using the proposed method. The unknown internal parameters of the PV panel circuit are extracted by using the PV array tool in Simulink, which is a simple method to obtain the PV parameters at certain weather conditions. Double-diode model results are compared with the single-diode model under various irradiances and temperatures to verify the performance and accuracy of the proposed method. The proposed method shows good agreement in terms of the I–V and P–V characteristics. A monocrystalline NST-120 W PV module is used to validate the proposed method. This module is connected to a variable load and tested for one summer day. The experimental voltage, current, and power are obtained under various irradiances and temperatures, and the I–V and P–V characteristics are obtained.

A large part of incident solar radiation on photovoltaic (PV) modules is converted into heat, leading to overheating and reduction of PV modules performance. The present work investigates the impact of rectangular aluminium fins (RAFs) and evaporative cooling represented by cotton wicks immersed water (CWWs) on the performance and thermal behaviour of the PV module. Results indicate that the evaporative cooling attained better cooling potential than RAFs, in which the PV module temperature was reduced by 22.3%, and the output power was enhanced by 73% thanks to continuous cooling of the PV module. A slight improvement in the PV module performance was observed with RAFs due to the increased heat transfer area, which reduced temperature by up to 6.7% and increased the output power of the PV module by up to 21.3 %. Exergy analysis shows a gradual increment of the electrical exergy and exergy efficiency using CWWs, which reduces the entropy generation of it more than RAFs. The study concluded that PV modules without cooling in hot climate areas may deteriorate their performance significantly.