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A novel Zig-Zag scheme for power enhancement of partially shaded solar arrays

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Abstract

This paper proposes a novel Zig-Zag scheme of arrangement for the total cross tied interconnection of photovoltaic modules for reducing partial shading losses and thus enhancing power generation. The performance improvement over classical total-cross-tied connection has been validated by extensive simulation results. The novel scheme of arrangement is also compared with the optimal total cross tied configuration and results show that the new scheme of arrangement showed very similar operational characteristics. The rearrangement of modules is performed without varying the electrical connection of the modules in the array. Simulation results shows that the new scheme of rearrangement lessens the number of multiple local maxima in power–voltage (P–V) characteristics which further simplifies the Global Maximum Power Point (GMPP) tracking algorithm. The performance of the system is investigated for five different shading patterns.

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... Thus, the length of the cabling is more than the T-C-T and Sudoku arrangements [40]. Futoshiki Sudoku, optimal Sudoku, unsymmetrical puzzle, zig-zag, dominant square logic, and improved magic square techniques have been proposed to improve the performance of T-C-T topology [41][42][43][44][45][46][47]. The shade dispersion static reconfigured techniques do not require any sensors, reconfiguration algorithm, and switching matrix. ...
... The symmetrical sections of S-P topologies are cross-tied (pink colored line). In Figure 3f, the PV modules (31,32,33,34,35,36) and (41,42,43,44,45,46) are connected at the same node. Hence, both the symmetrical sections of S-P topologies are in series connection. ...
... Thus, the same current flows through the S-P and T-C-T topologies. The S-P topology is modeled with the modules (11,21,31), (12,22,32), (13,23,33), (14,24,34), (15,25,35), and (16,26,36), and the T-C-T topology is modeled with the modules (41,42,43,44,45,46), (51,52,53,54,55,56), and (61, 62, 63, 64, 65, 66). S-P-T-C-T topology performance is superior over S-P, B-L, H-C, and S-P-C-T topologies under most NUOCs. ...
Article
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The photovoltaic (PV) system center inverter architecture comprises various conventional array topologies such as simple-series (S-S), parallel (P), series-parallel (S-P), total-cross-tied (T-C-T), bridge-linked (B-L), and honey-comb (H-C). The conventional PV array topologies under non-uniform operating conditions (NUOCs) produce a higher amount of mismatching power loss and represent multiple maximum-power-points (M-P-Ps) in the output characteristics. The performance of T-C-T topology is found superior among the conventional topologies under NUOCs. However, T-C-T topology’s main limitations are higher redundancy, more number of electrical connections, higher cabling loss, poor performance during row-wise shading patterns, and more number of switches and sensors for the re-configuration of PV modules. This paper proposes the various optimal hybrid PV array topologies to overcome the limitations of conventional T-C-T array topology. The proposed hybrid topologies are such as series-parallel-cross-tied (S-P-C-T), bridge-link-cross-tied (B-L-C-T), honey-comb-cross-tied (H-C-C-T), series-parallel-total-cross-tied (S-P-T-C-T), bridge-link-total-cross-tied (B-L-T-C-T), honey-comb-total-cross-tied (H-C-T-C-T), and bridge-link-honey-comb (B-L-H-C). The proposed hybrid topologies performance is evaluated and compared with the conventional topologies under various NUOCs. The parameters used for the comparative study are open-circuit voltage, short-circuit current, global-maximum-power-point (GMPP), local-maximum-power-point (LMPP), number of LMPPs, and fill factor (FF). Furthermore, the mismatched power loss and the conversion efficiency of conventional and hybrid array topologies are also determined. Based on the results, it is found that the hybrid array topologies maximize the power output by mitigating the effect of NUOCs and reducing the number of LMPPs.
... Here the PV equivalent model is based on the single diode model [35]. PV cell is considered to be a variable current source parallel to photodiodecurrent (Iph) and can be expressed as, Where, se R and sh R are PV cell series and shunt resistance respectively, short circuit (S. ...
... PV cell is considered to be a variable current source parallel to photodiodecurrent (Iph) and can be expressed as, Where, se R and sh R are PV cell series and shunt resistance respectively, short circuit (S. C.) current and solar irradiance are expressed as SC I and Sx, i K -Cell temperature coefficient [35]. PV surface temperature is determined with help of actual temperature (Tx) and standard test condition temperature (TST) as, ( ) ...
... Similar PV cells and bypass diodes are inter linked in the PV module to avoid damage from hot spot phenomenon under PSCs. An electrical equivalent model of PV module is depicted in Fig. 3 [35]. The module current expression with bypass diode is shown in Eq. (3) ...
Article
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In this paper, the significance of cross-tied link between the solar photovoltaic (PV) modules in an array during partial shading conditions (PSCs) is introduced. In order to conduct a detailed analysis, twenty numbers of 20W PV modules (4×5) are arranged in a series-parallel (SP) configuration. The change in the pre-arranged SP configured PV array is implemented using a cross-link matrix switch between parallels based on shadow patterns. The switch matrix based modified PV array configuration is called Adaptive-cross-tied (A-CT) configuration. An embedded system based adaptive switch matrix (ASM) controller is developed to control the cross-linking connections between the PV modules under the PSCs to improve global maximum power. In addition, a performance analysis is carried out and compared all PV modules arranged in conventional SP and A-CT configurations. Moreover, realistic shadow test cases are under consideration to characterize current-voltage (I-V) and power-voltage (P-V) characteristics. The output power of the PV array decreases as well as the P-V curves show multiple power maxima points., such as the local maximum power point (LMPP) and the global maximum power point (GMPP). LMPP and GMPP locations, mismatch loss (ML), enhanced fill factor (FF), decreased power loss (PL) and performance ratio (PR) are indicators of performance during experimental and MATLAB/Simulink studies.
... All these afore-mentioned partial PSCs are eventually augmenting the magnitude of MML, limiting the actual power capacity (output) and causing multiplelocal peaks in the characteristic curves of any PVA. Therefore, optimal interconnection(s) of PV modules under PSCs is essentially discussed in the literature in the form of optimization techniques (say Genetic Algorithm) [17], where global optimum is achieved 7 out of 10 trials; Mathematical formulation of algorithm [19] is carried out to develop new rules of shifting PV modules in a subarray of any generic PVA system without violating the rules of Su-Do-Ku pattern; Magic Square (MS) configuration [22] presents a new method of arranging modules, such that non-diagonal elements are filled later than that of diagonal elements in a TCT-configured PVA; a flow chart of an algorithm is obtained [23] according to the odd & even position of the row elements of module; new rules of optimal interconnections [24] are proposed and the parallel connected shaded module is found to be the most non-preferred orientation amongst all; a general formulation is proposed such that the applied pattern can be expanded to any generic array [19,23,25,32] owing to reflect the universal attribute for the assumed constraint. ...
... On the manufacturer front, the data-sheet (provided) less often contains the information about certain parameters [Utilization factor (UF), Fill factor (FF), Performance Ratio (PR), MML etc], essentially required for qualitative analysis of PVA, and therefore need to be evaluated. Most of the reviewed papers have identified these parameters initially at standard test conditions (STC) as well as to the real time ambient conditions under variable PSCs [18,19,20,24,25,27,29,31,32]. The fundamental characteristics curve (V-P curve) of [15,22,24,28,31,32] PVA obtained for static, dynamic and random PSCs extracts the location of global maximum power point (GMPP) for the respective proposed configurations such that probability of misleading MPPT might reduce, although (in case of multiple peaks) location of global peak (GP) is identified via considering the module currents as per the order in which panels are by-passed. ...
... Other approaches, under MSH conditions, require the estimation of parameters (solar elevation angle, azimuthal angle, tilt angle, PV-azimuth angle, etc) to obtain %age annual Performance Enhancement (PE) [29]. One of the most important parameters (Power loss (PL)) is investigated by significant number of research papers [16,19,20,24,25,28,32] according to the concerned element employed for PL ( say by-pass diode, parasitic resistive loss, loss due to relative power levels, resistance of the wires used in interconnection of PV modules, etc.). ...
Article
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Dwelling upon the exploitation of solar energy is an excellent choice, but at the same time, its subsisting limitations cannot be overlooked. Partial shading is one of the major concerns that exhibit multiple peaks, due to mismatch losses (MML), in the electrical characteristics of solar photo-voltaic (PV). The presented paper, therefore, is an attempt to systematically investigate the performance of existing static and dynamic configurations (whether simulation or experimental based) of photovoltaic array. The observations and analysis is carried out in terms of optimal interconnection by puzzle based re-configurations with respect to traditional techniques facing drawbacks due to ineffective shade dispersion. Alternative puzzle based approaches are identified and taxonomized according to their attribute towards ease of use, applicability, durability and reliance. An endeavor is made to recognize the current trends of accelerated growth in the field of solar photovoltaic and the seeds of rejuvenated possibilities are sown to hope for fertile ground of future research.
... Moreover, conventional SP, BL, HC, TCT and reconfigured optimal TCT, NTCT PV array configurations were investigated under PSCs. Among all, suggested NTCT was characterised as having better performance [30][31][32][33][34]. In [35], the authors solved the issue of high length wire requirement for PV module interconnections during the reconfiguration methodology. ...
... The TCT PV array configuration arrangement is accomplished from SP arrangement by interconnecting cross-connections across individual row-column of the PV array [34]. The voltage generated by the PV array can be exhibited as the sum of all the voltages of 'n' number of rows. ...
... The PV modules are further subjected to enlarge shade distribution under shading conditions. The recommended scheme of replacement of PV modules can be accepted in arrays of dimension very easily [34]. The first column element in classical TCT arrangement are kept in the similar column for the proposed NTCT configuration as shown in Figure 2. ...
Article
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Large size Photovoltaic (PV) systems face large number of issues based on the malfunction and unfavourable climatic conditions such as partial shading conditions (PSCs). These PSCs are the major causes of PV systems’ performance degradation. In this paper, symmetric matrix (SM) game puzzle is used to reconfigure the electrical connections of PV array system. Present shade dispersion (SD) methodology is based on the ‘Physical reallocation of PV module-fixed electrical connections’ (PRPVM-FEC) principle. Modification in the electrical connections of conventional total-cross-tied (TCT) PV array configuration introduces new ‘Symmetric Matrix-Total cross-tied’ (SM-TCT) configuration. An extensive comparative study of conventional TCT and Novel-Total cross tied (NTCT) configurations with proposed SM-TCT configuration prove the effectiveness to achieve higher performance. The MATLAB/Simulink results are obtained on the basis of non-linear nature of current-voltage (I-V) and power-voltage (P-V) characteristics. SM-TCT, Shape-do-Ku, NTCT and TCT configurations are examined under three realistic PSCs in terms of power and voltage at global maximum power point (GMPP), improved fill factor (FF), reduced power losses (PL), performance ratio (PR) and power enhancement (PE).
... Several researchers [15][16][17] showed that some power drop might also occur when using TCT configuration under certain shading conditions. Other promising techniques for mitigating partial shading issues are using reconfiguration strategies [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34]. The reconfiguration methods are categorised into; dynamic and static. ...
... Hence, in this technique, a simple array such as TCT can still be modified or "reconfigured" by conceptually moving any module to a different physical location in the array without changing any electrical connections. The physical reconfiguration strategy does not require additional switching devices compared to the above dynamic reconfigurations techniques, reducing the system complexity, cost and size [25,31]. ...
... This technique, however, suffers from similar issues as those of Sudoku, where both arrangements are unable to extract most of the available power under a column-wise shading pattern. More recently, many other reconfiguration algorithms have been reported in the literature [18,21,24,25,[31][32][33]. ...
Article
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Partial Shading Conditions (PSCs) significantly impact the output power performance of a Photovoltaic (PV) solar array. Such an issue can be addressed by partly or wholly cross-tying the modules in the array rows and reconfiguring the positions of these modules within it. This paper proposes a novel Magic Square-Enhanced Configuration (MS-EC) algorithm to overcome the partial shading issues. Hence, the proposed algorithm disperses the shading effects more evenly over the entire array surface, reducing the conductions losses due to the bypass diode operation. When using the MS-EC scheme, PV modules are physically re-wired and moved into other locations in the array structure without altering their electrical connections. The key advantage of the MS-EC reconfiguration over the existing techniques is that it requires fewer iterations, easing the Maximum Power Point Tracking of the array. The performance of the proposed algorithm is assessed using several indicators, such as maximum power generation, number of iterations required, complexity and mismatched power losses. MATLAB-SIMULINK software environment is used to simulate the MS-EC scheme. Hence, the former method compares favourably with the existing techniques and a traditional Tied-Cross-Ties (TCT) configuration, giving average power improvements of 16 – 43% under most of the realistic weather conditions.
... A zig-zag arrangement was presented by Vijayalekshmy et al. [100,101] and Satpathy et al. [102] for a unique configuration to disperse distinct shading effects. Vijayalekshmy et al. [100] suggested that repositioning of the PVMs in case of LS configuration is focused on the columns. ...
... A zig-zag arrangement was presented by Vijayalekshmy et al. [100,101] and Satpathy et al. [102] for a unique configuration to disperse distinct shading effects. Vijayalekshmy et al. [100] suggested that repositioning of the PVMs in case of LS configuration is focused on the columns. They put forward a novel zig-zag PVA arrangement for repositioning the PVMs in both ways, i.e., column-wise and row-wise. ...
... Vijayalekshmy et al. [100] Zig-zag • Arrays of any dimension type can benefit from this. • PVA performance is evaluated using eight distinct sorts of parameters. ...
Article
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The output power generated by a photovoltaic cell decreases remarkably because of irregular irradiance pattern. Thus, the overall system performance is degraded. The decrease in the power output is not dependent on the shaded area but is rather dependent on the array configuration and the shading pattern. To eliminate partial shadings, many strategies have been documented in the state‐of‐the‐art literatures. These strategies may not improve the maximum output power to the required level but definitely to a certain extent. Thus, to minimize these losses, a promising reconfiguration approach is needed, i.e. reconfiguring the photovoltaic modules inside the photovoltaic array to improve the maximum power output. These techniques are broadly divided into two categories viz., static and dynamic reconfiguration methods. The advanced photovoltaic array reconfiguration solutions to improve global power output under mismatch and partial shading scenarios is presented in this paper. According to the results of the review paper studied in this research, dynamic approaches are costlier as compared to static reconfiguration strategies, but they are more effective to reduce the partial shading impact in comparison to the static techniques. This article is protected by copyright. All rights reserved.
... The various PV array reconfiguration designs that follow static methods are Sudoku (Rani et al. 2013), optimal Sudoku (Potnuru et al. 2015;Horoufiany and Ghandehari 2018), improved Sudoku (Sai Krishna and Moger 2019b), Zig-Zag method (Vijayalekshmy et al. 2016), Latin square method (Pachauri et al. 2018), magic square (Yadav et al. 2017), placement of shadows with distance d (Malathy and Ramaprabha 2018), skyscraper puzzle (Nihanth et al. 2019), and shadow puzzle (Yadav et al. 2016). ...
... It was concluded that the improved SuDoKu performed better than the SuDoKu and the optimal SuDoKu. Vijayalekshmy et al. (2016) employed decreasing partial shading losses and increasing power generation, being done by a static PV module reconfiguration technique called the Zig-Zag method. A magic square arrangement for the TCT PV array has been presented by Yadav et al. (2017) to extract maximum output power under PSC. ...
Article
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This paper introduces a novel reconfiguration technique, called Knight's tour to extract maximum power from photovoltaic (PV) arrays in partial shading conditions. The Knight's tour reconfigures the PV arrays based on the Knight's movements on the chessboard. The proposed procedure achieves the maximum power values by spreading partial shadows in all rows. Knight's tour can be applied to a variety of PV arrays in different dimensions and sizes. Accordingly, the Knight's tour procedure is applied to 4 cases in square and rectangular shapes with different dimensions and various shading conditions in each case. To make a direct comparison and present the effectiveness of the suggested procedure, the Total-Cross-Tied connection model and conventional methods such as SuDoKu, optimal SuDoKu, improved SuDoKu, and Skyscraper Puzzle are also implemented to the introduced cases. The results of the maximum power point tracking in each case are evaluated by indicators such as Global Maximum Power Point (GMPP), Fill Factor, Mismatch Loss, and efficiency. Finally, evaluations emphasize the ability and effectiveness of the Knight's tour solution compared to other methods by achieving the GMPP values such as 74.7I_m V_m, 66.6I_m V_m, 46.8I_m V_m, and 109.8I_m V_m for cases 1 to 4, respectively. The Knight's tour method can be utilized as an efficient tool for the PV arrays in real-world systems that suffer from partial shading.
... Reconfiguration for PV array topologies emerged as an alternative solution for power enhancement [15]. It categorizes as a physical and dynamic reconfiguration [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. In dynamic reconfiguration, the module position remains unchanged while the electrical connections alter. ...
... The authors in [25] proposed a Zig-Zag puzzle scheme (NTCT). It works so that one column elements in the array retain constant, where the first row elements are arranged diagonally. ...
Article
Partial shading is the prevailing problem in Photovoltaic arrays. It results in severe consequences like multiple peaks in electrical characteristics, hot spots on Photovoltaic panels, disruptions in tracking maximum power and reduced output power. During most of the shading conditions, the shade concentrates in a particular area of the Photovoltaic (PV) array. This shading reduces PV array efficiency. Several physical reconfiguration schemes based on puzzle patterns are proposed to minimize this problem. The majority of these methods deduced to fixed PV array size for which the algorithm has proposed. Further, few of them are applicable only to lower size PV array. This paper presents a novel magic square puzzle for scattering the shade in the PV array to overcome the above constraints. In this method, the module physical position remains the same. However, the electrical wiring alters according to the puzzle pattern to change the row current in the Total-Cross-Tied topology PV array. The efficiency of the proposed system is examined under different shading conditions using characteristic curves. The relative analysis was carried between the conventional Total-Cross-Tied topology and the proposed Novel Magic Square-based Total-Cross-Tied topology. The MATLAB/SIMULATION results demonstrate that placing the modules according to the proposed reconfiguration method minimizes the peaks and enhances the output power (11.53%), with the global peak always on the right side of the PV curve under partial shading conditions.
... The topologies derived from SuDoKu game theory have limitations that it can be implemented where the PV array has an even number of rows [19]. In a real-world scenario, the shadow on the PV panels is rarely in the straight lines or a linear pattern, the cloud movement and its modeling are presented by S. Vijayalekshmy et al. for a TCT and rearranged TCT topology [20]. However, the predominant factor for cloud movement and cloud shade due to wind was not taken into consideration. ...
... The initial values of wolves are done using (19) and (20) function and, moreover, a pack of them is formed. ...
Article
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The extraction of maximum power is a big challenge in solar photovoltaic-based power plants due to varying atmospheric and meteorological parameters. The concept of array reconfigu-ration is applied for the maximum power extraction in solar PV plants. Using this approach, the occurrence of multiple peaks in P-V and I-V characteristics during partial shade can be smoothened and reduced significantly. Partial shading due to the movement of the cloud is considered in the research. The cloud movement mainly because of velocity and wind direction is used for creating various shading conditions. The main focus is to reduce the power losses during partial shading using a nature-inspired optimization approach to reconfigure the array for different types of shading conditions. A grey wolf optimizer-based bridge-linked total cross-tied (GWO-BLTCT) configuration is proposed in this paper. The performance of the proposed topology is compared with standard and hybrid topologies, namely, series-parallel, total cross-tied, BLTCT, and SuDoKu-BLTCT, based on performance indicators such as fill factor, performance ratio, power enhancement, and power loss. The proposed GWO-BLTCT outperforms the remaining topologies due to the least power loss and high fill factor. It also has the highest average power enhancement and performance ratio with 23.75% and 70.02% respectively.
... In another study [134], devised an effective strategy to configure a non-symmetrical 5 × 4 array and subjects the system to a wide variety of shading patterns. It emerges as one of the superior methods in terms of reduced power losses and high fill factor under partial shading conditions. ...
Article
To simultaneously cover multiple wireless services and protocols, the antenna in communication devices should operate over a wide and ultra-wide frequency band. The use of wide/ultra-wideband antennas not only lessens the number of antennas necessary to cover multiple frequency bands but also decreases the system complexity, size, and costs. To operate over the ultra-wide frequency band, in this paper a CPW-fed small antenna is reported for portable communication devices. The anticipated antenna comprises a bow-tie-shaped patch and two ground planes. One inverted L-shaped and one extended U-shaped ground plane are asymmetrically placed with the main radiator which helps the antenna prototype to realize a functional band of 3.05 – 11.25 GHz (VSWR ≤ 2). In the functional band, the studied antenna accomplished a maximum peak gain of 4.98 dBi and maximum efficiency of 94.4%. Moreover, it exhibits symmetric omnidirectional radiation patterns and good time-domain behavior. The lucrative characteristics such as simple design, very small size (24.5 × 20 mm²), ultra-wide operating band, good gain and efficiency, stable radiation characteristics, and good time-domain characteristics make it a potential candidate to be used in portable communication devices.
... In static reconfiguration, the physical position of the modules is changed to reduce the mismatch among modules whereas, in dynamic reconfiguration, the connections of the modules are changed concerning the shading pattern by using switches [23]. Some of the static reconfiguration strategies include: shade dispersion scheme (SDS) [24], fixed electrical reconfiguration (FER) [25], dominance square (DS) [26], zigzag [27], shade dispersion physical array relocation [28], shade dispersion positioning [29], Sudoku [30], improved Sudoku [31], modified Sudoku [32], competence square [33], magic square [34], etc. These strategies utilize rearrangement concepts or algorithms to change the position of the module to disperse the shading however, changing the module's position requires huge manpower mainly in the case of large power plants that comprise a large number of big size modules. ...
... A novel zig-zag scheme for power enhancement under PVACs is described in Ref. [24]. A new technique to interconnect the modules so that the effects of the partial shading can be distributed is put forth in Ref. [25]. ...
Article
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This manuscript focuses on the rearrangement of the structure of the photovoltaic (PV) array under different shading conditions. It aims to analyze the mismatch power losses (MPLs) due to irregular illumination over PV array (PVA). The impact of partial irradiance not only affects the electrical power but also causes multiple peaks in the P-V and I-V curves. The formulation of the best PVA configuration (PVAC) to achieve maximum output even under partial shading conditions is the deciding factor for the topologies considered. To aid the maximum power extraction, a new SuDoKu PVAC is designed like hyper SuDoKu (HS). This new structure is compared with the already existing PVACs such as bridge link, honey comb, series parallel, total cross-tied, and SuDoKu in the effect of considerable cases of shadowing. MATLAB/SIMULINK is used for the designing and computer based modeling of all these PVACs is considered in this work. The evaluation of these arrangements has been done by keeping several performance factors as the deciding pivot points. These factors include MPL, efficiency, global maximum power point (GMPP), and fill factor (FF). The results obtained through this document suggest that the HS arrangement proposed here gives the best outcome for each shading condition. The proposed HS structural arrangement of PVA deals with significantly superior GMPP, FF and efficiency while maintaining minimum MPL in comparison to the other arrangements.
... Also, they can't noticeably increase the output power. The zig-zag [38] and the Dominance square (DS) [14] methods require very high-cost connections and wiring complexity. The DS technique follows an arbitrary reset process that isn't suitable for real-time situations. ...
Article
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Non-uniform solar irradiance on the photovoltaic arrays decreases the output power due to the partial shading conditions. In this paper, the distribution of shade in the photovoltaic array rows is done by reconfiguring the shaded modules related to the photovoltaic array. The method proposed in this paper is a static approach based on prime numbers. Due to the pattern of prime numbers, it reconfigures the shaded modules in each row. The effectiveness of the proposed procedure is done by testing five different shading patterns in 9 × 9 and one 23 × 23 Total-Cross-Tied PV arrays. The ability and superiority of the proposed method are tested by comparing the results of the suggested method of prime numbers with the results of the Total-Cross-Tied, Sudoku, optimal Sudoku, improved Sudoku, and Dominance square methods. Comparison and evaluation of the results are done by different statistical performance indicators. The evaluations showed that the prime numbers procedure with the values of 9.15%, 7.72%, 8.21%, 8.83%, 8.95%, and 8.77% for cases 1 to 6, respectively, had the highest power factor compared to other methods employed. In addition, the suggested method has the lowest mismatch power losses compared to other procedures by achieving the values of 3.84%, 4.87%, 4.53%, 4.10%, 3.97%, and 4.19% in cases 1-6, respectively. The results of the comparisons strongly emphasize the high ability of the proposed method compared to other methods studied. It should be noted that scalability, high-performance speed, and low cost are important advantages of the prime number method so that this method can be implemented on real-world PV arrays.
... The author concluded that the proposed pattern has improved the GMPP under most PSCs. The author of [28] proposed a Zigzag technique, to rearrange the location of the modules within the PV array based on the proposed technique to reduce PL and improve FF. The mathematical analysis of the HC configuration is analyzed in [29]. ...
Preprint
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The Photovoltaic (PV) module subjected to partial shading exhibits multiple peaks in the power-voltage characteristics leading to mismatch losses. This loss is a function of module interconnection, shading area and shading pattern. The hybrid configuration has found to be superior to improve the performance of the PV array during partial shading conditions. This work aims to minimize the mismatch loss by using an optimized jigsaw puzzle based reconfiguration technique. The physical position of the modules is rearranged based on the jigsaw puzzle pattern without altering the electrical connections. The performance of the proposed jigsaw puzzle pattern is configured on different interconnection schemes like total-cross-tied, series-parallel total-cross-tied, bridge-link total-cross-tied and honey comb total-cross-tied. For the different shading patterns, the performance of the proposed reconfiguration technique is compared with the existing puzzle based reconfiguration technique schemes such as ken-ken, skyscraper, odd-even and latin square in terms of global maximum power point, power loss, mismatch loss, fill factor, execution ratio and performance enhancement ratio. To validate the results, the performance of the proposed reconfiguration technique is tested in MATLAB/Simulink environment and experiment setup for a 4x4 PV array. The proposed jigsaw puzzle based reconfiguration technique mitigates the occurrence of multiple local power point on the power-voltage characteristics. Hence, the simulation results show the proposed jigsaw based reconfiguration technique improves the output power by 14.01% compared to the existing reconfiguration technique under partial shaded conditions. The effectiveness of the jigsaw puzzle arrangement is also validated experimentally and the results are presented in this paper.
... The Su Du Ko puzzle (Rani, Ilango, and Nagamani 2013) based rearrangement is developed to reduce the mismatch losses in PV arrays by distributing shading effects and this particular method is further modified to reduce the line losses during installation (Rao et al. 2015). A zig-zag arrangement (Vijayalekshmy, Bindu, and Iyer 2016) of PV modules in a PV array is analysed for different shading patterns including corner shading. The performance of zigzag method is analysed by considering performance ratios and fill factor. ...
Article
Renewable energy sources are receiving wide popularity due to the shortage of fossil fuels and environmental problems caused by conventional energy sources. Solar photovoltaic energy is a widely used sustainable energy source. The power developed by a solar cell is greatly influenced by the insolation level. Partial shading occurs when one or more photovoltaic (PV) cells receive lesser radiation as compared to other cells, which in turn affects the overall electrical performance of PV cells including reduced generated power. This paper proposes a newly developed configuration known as Reformed-Total cross-tied (R-TCT) to improve the power generation during partially shaded conditions in small-scale PV systems, especially for urban and rural area applications. The basic idea of this paper is to redistribute the shaded modules of a row to other rows such that the number of shaded solar PV modules of each row are nearly same. The proposed method is validated by simulation and also by hardware implementation. The simulations and experiments are done on eight different shading cases and found that the proposed method gives either superior or same performance as that of existing TCT, LS (Latin Square)-TCT, and D-TCT configurations.
... The proposal for an optimal SuDoKu (OS) pattern is given in Ref. [19] to optimally minimize the required length of connecting wire within the array. The zig-zag scheme was introduced in Ref. [20] to enhance the PVA power under PSC. ...
Article
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Individual performance of photovoltaic (PV) modules is contravened by mismatch losses which results in blockage in most of the solar power generated by the PV array (PVA). Partial shading conditions (PSCs) are the main causes of these losses. Several techniques have been discussed to reduce the issues caused by PSCs. Reconfiguration techniques have been proven to be one of the most successful methods that help towards this cause. In this method, the location of PV module (PVM) in the PVA is reconfigured so that the shading effects get distributed throughout the entire array and, hence, maximizing the power output. Two novel reconfiguration patterns such as canonical SuDoKu (CS) and multi diagonal SuDoKu (MDS) for total cross tied (TCT) configuration have been put forth in this manuscript. This approach aims to rearrange the PVMs in the TCT array as per the fed in patterns without causing a change in the internal electrical connections. Further parts of the manuscript focus on the comparison of the proposed pattern's performance with other pre-existing PVA arrangements such as, TCT, SuDoKu, optimal SuDoKu (OS) and modified SuDoku (MS) by taking into account the effects of global maximum power (GMP) point, mismatch power loss, fill factor and performance ratio. The results obtained from the detailed analysis presented in this paper gives proper evidence that, in many cases, the GMP is amplified in the CS and, in all cases, GMP is amplified in the proposed MDS PVA under different shading conditions.
... In another study [134], devised an effective strategy to configure a non-symmetrical 5 × 4 array and subjects the system to a wide variety of shading patterns. It emerges as one of the superior methods in terms of reduced power losses and high fill factor under partial shading conditions. ...
Article
This paper reviews and evaluates the hardware solutions to mitigate the effect of partial shading for grid-connected photovoltaic (PV) system. It encompasses both the module-level as well as the array-level approaches. The former enhances the energy yield by maximizing the power extraction capability of each individual module. Here, three methods, namely the micro inverter, the power optimizer and the energy recovery circuit are covered. On the other hand, the array-level mitigation—which includes the dynamic and static array reconfigurations optimize the arrangement of the modules to minimize the effect of partial shading on the energy yield. Besides updating the important aspects of the technologies, this paper delves into the economic viability of the solutions, as well as the challenges and future trend. In addition, it benchmarks the performance of the module-level solutions with the system with string inverter using Simulink. It is discovered that if the plant is highly shaded, the net energy gain of the micro-inverter and power optimizer is significant. On the other hand, if the shading is non-existent, employing these devices can be counterproductive (in terms of yield).
... One common drawback persists in these techniques; they cannot be extended to array size other than the proposed configurations. To resolve this issue zig-zag method [23], adjacent shift [24] and dominance square technique [25] involves both row and column-based displacement of modules. However, it increases the complexity of interconnections. ...
Article
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Solar Photovoltaic array may often be subjected to partial shading, which may lead to uneven row current and creates local maximum power point on the power-voltage characteristics. One of the effective approaches to dilute the concentration of partial shading is the array reconfiguration technique. This study proposes a ken-ken puzzle-based reconfiguration technique for 4x4 total-cross-tied configuration to rearrange the position of modules within the array and to improve the maximum power under partial shading conditions. Further, the performance of the ken-ken puzzle arrangement is compared with the total-cross-tied configuration and existing reconfiguration techniques namely odd-even, Latin Square, and Sudoku reported in the literature. The performance of all these configurations is evaluated in terms of fill factor, mismatch loss, power loss, execution ratio, and performance enhancement ratio. The proposed ken-ken puzzle-based reconfiguration technique mitigates the occurrence of local maximum power point and eliminates the need for a complex algorithm to track the global maximum power point. The simulation result shows that the KK puzzle-based reconfiguration technique has obtained an improved PE of 10.85 % compared to TCT configuration, followed by LS, Sudoku, and OE. Also, the experimental result shows the effectiveness of the ken-ken in diluting the effects of partial shading when the rows of the photovoltaic array are shaded. The ken-ken puzzle-based reconfiguration technique reduces the complexity, maintenance and increases reliability, scalability of the PV array.
... Compared to dynamic PV array configuration, static PV array configuration is more suitable to apply to large-scale PV systems as it does not require any meters, switching matrix, and only displays the switching process one time. There are a number of static PV array reconfiguration methods, such as magic-square puzzle pattern [12], dominant-square [13], logic-based number puzzle [14], zigzag scheme [15]. Among them, Sudoku (SDK) pattern is the best configuration to alleviate the partial shading effects [16]. ...
... To overcome these shortcomings, an optimal Sudoku based PV arrangements are proposed in Potnuru et al. (2015) which reduces the mismatch losses in PV array and witness a simple MPPT control design. A novel Zig-Zag design for the TCT interconnection of PV modules is proposed in Vijayalekshmy et al. (2016) to mitigate the shading losses and to enhance power generation. In Bonthagorla and Mikkili (2020), a 7Χ7 PV array configuration is investigated considering seven shading patterns and it is observed that triple tied (TT) PV array configuration gives better performance with reduced cable cost in comparison to TCT configuration. ...
Article
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Partial shading (PS) is a major challenge faced by photovoltaic (PV) arrays invoking mismatch loss (ML). In this paper, the effect of PS on PV array performance is analyzed through experimental results and MATLAB simulation. The effect of PS on PV characteristics is investigated in two conditions. In condition one, modules are not coupled with bypass diodes, and in condition two modules are equipped with bypass diodes. New mathematical equations have been derived to calculate ML for condition one, and for condition two; locations of power peaks are identified in the power-voltage (P-V) curve. For both the conditions, theoretical results are verified through experimental results. From the obtained results it is observed that the error in loss calculation for condition one is less than 2% and for condition two, power peaks are being identified analytically with less than 3% error. To reduce the effect of PS on PV array, different configurations of the PV array were considered in the earlier literature. Among all, Total Cross Tied (TCT) PV array configuration is popularly used for its improved performance. To curtail the cost of TCT, two-hybrid array configurations such as TCT with bridge link (TCT+BL) and TCT with honey-comb (TCT+HC) are proposed here. Performances of different array configurations are analyzed considering various parameters such as global maximum power point (GMPP), currents and voltages at GMPP, the number of local peaks, shading losses, and mismatch losses. It is observed that proposed array configurations outshine in performance by reducing the amount of ML and the number of local peaks in the P-V graph, mainly for the stochastic shading patterns.
... Compared to dynamic PV array configuration, static PV array configuration is more suitable to apply to a large-scale PV system as it does not require any meters, switching matrix, and only make a switching one time. There are a number of static PV array reconfiguration methods, such as magic-square puzzle pattern [13], dominant-square [14], logic-based number puzzle [15], zigzag scheme [16]. Among them, Sudoku pattern is the best configuration to distribute subarray shading effects [17]. ...
... These techniques do not require additional switching devices, thereby reducing the complexity of the controller. The reported static reconfiguration techniques are Futoshiki puzzle [30], nonsymmetrical reconfiguration [31], zig-zag [32], magic square [33,34], dominant square [35], competence square [35][36][37][38][39], SuDoKu puzzle [40][41][42], odd-even reconfiguration [43], shade dispersion physical array relocation [44], and skyscraper puzzle [45]. However, the static mitigation methods are complicated when manually applied to considerable dimensions of PV arrays. ...
Article
Full-text available
The partial shading on PV arrays causes power decrease, hot spots, and damage to its components. In addition, the performance of the PV array is reduced for the internal mismatch. This work proposes a novel dynamic, on line, low costs, and automatic method to mitigate these effects. The method considers the mismatch due to partial shading and cell variability. In this method, the entire PV array is fully dynamic, and auxiliary PV modules are not required. The PV modules are electrically rearranged while the same interconnection scheme is maintained. The method is based on the temperature, the global voltage, and the global current of the entire PV array. These global measurements reduce the number of sensors, signal processing, computing time, electrical connections, and implementation cost. The electrical rearrangement of the PV modules is controlled by a neuro-fuzzy algorithm, a connection control, and a switch matrix. The proposed approach was implemented in hardware and validated experimentally in a real PV array. The results show that the method has 97% effectiveness in distinguishing the cause of power decrease, a 100% effectiveness in locating the shaded PV module, and a 10% increase in the PV array output power.
... By relocating the PV panels in their original columns, but in different row positions, with modules in the first row reconnected as the diagonal element, the novel ZigZag (ZZ) scheme in reference [143], can straighten the array P-V characteristics, thus decreasing the number of local maxima. Each column's elements (which represent a PV module) are kept within the same column: no horizontal shifting is made between alternate columns. ...
Article
This paper aims at exploring different PhotoVoltaic (PV) array Reconfiguration (PVR) methods, used to reduce the negative impacts of Partial Shading Conditions (PSCs), that could affect the performance of a PV system (i.e. hotspots, electrical mismatch, etc.). The classification of different PVR techniques is formed under three main categories: physical, electrical, and physical-electrical combination. Physical PVR alters the actual locations of the panels within the array. Referred to as static reconfiguration methods, this set includes puzzle based, number based, symmetry based, distance maximizing based, and nature inspired methods. On the other hand, electrical PVR reorders the electrical interconnections between PV panels, and is composed of algorithm based, artificial intelligence based, hybrid, and basic/improved electrical configurations. A combined PVR method hybridizes the two precedent categories. Each method from the three main sets, is critically compared to the relevant others, according to a mathematical model, which includes many performance indices: Fill Factor (FF), Mismatch Power Loss (PML), Percentage Power Loss (%PLoss), Performance Ratio (PR), Execution Ratio (ER), Efficiency (η), Percentage of Power Enhancement (%PE) and DC output power (PDC). The thorough investigation of different PVR techniques, resulted that a Total Cross Tied (TCT) configured PV panels, physically relocated by means of Static Shade Dispersion Physical Array Relocation (SD-PAR) algorithm, while interfered with a switching matrix controlled by Modified Harris Hawks Optimizer (MHHO) algorithm, could be an optimum and effective solution to passively mitigate PSCs’ effects.
... The evaluations emphasized the high performance of the Magic-Square method compared to other conventional SuDOKu-based methods. In [51], decreasing partial shading losses and increasing power generation have been done by a static PV module reconfiguration technique called the Zig-Zag method. The reconfiguration of PV array modules has been done by presenting a new static-based method called prime numbers in [52]. ...
Article
Full-text available
Non-uniform irradiance due to partial shading conditions (PSCs) reduces the power delivered by the photovoltaic (PV) cell. The output power reduction in the PV arrays directly depends on the shading pattern and type of array configuration which is selected. So far, many dynamic and static reconfiguration methods have been used for maximum power point tracking under PSCs in the PV arrays. However, most conventional methods suffer from some major problems such as the need for additional equipment and sensors, complex wiring, the use of expensive sensors, production of complex switching matrices, high costs, and inability to reconfigure PV arrays with very small, large, and non-square sizes. Accordingly, this paper, after reviewing the dynamic and static PV array reconfiguration methods, presents a novel static-based technique called 8-Queen's for reconfiguring the PV modules corresponding to the Total-Cross-Tied (TCT) inter-connection PV array. The 8-Queen's technique has a great ability to apply on high dimensions and rectangular shapes PV arrays and is based on the movement of 8 queens on the chessboard so that none of the queens can attack the others. The effectiveness of the suggested method is expressed by implementing it on 7 cases of the TCT PV array in different sizes and various PSCs. In a comparative scenario, the performance and effectiveness of the proposed 8-Queen's technique are evaluated compared to other conventional methods. Indicators of global maximum power point (GMPP), fill factor, power efficiency, and mismatch losses evaluate the results of the employed methods. The evaluation of results represents the effectiveness of the 8-Queen's technique compared to other used methods. In addition, the performance evaluation of the proposed technique in real-world PV arrays is performed by modeling a sample PV array taking into account measurement errors. The results in this step also show that the proposed technique can also provide acceptable performance for solving problems related to maximum power point tracking under PSCs in PV systems.
... This technique is based on altering the physical location of PV modules without changing in electrical connection. The authors in [26] suggested the Zig-Zag reconfiguration for a 4 × 3 TCT-connected of PV array. The outcomes of this technique generates higher power than the TCT configuration. ...
Article
Photovoltaic (PV) plants can be exposed to partial shading, which reduces the energy production and causes multi-peaks to form in the Power-Voltage (P-V) curve. As a result, the row currents of the PV modules will not be constant. Several techniques have been proposed to overcome partial shading, such as the static and dynamic reconfiguration techniques, with both aiming to reduce the difference in the row currents to improve energy production. Minimization of the row current via static techniques requires laborious work and extra wiring. On the other hand, dynamic techniques require an extensive monitoring system to support different tasks. Therefore, to improve the power generated from the PV array, this paper suggests a new reconfiguration technique for PV panels using Genetic algorithm (GA) and two main reconfigurable steps based on a switching matrix. In this technique, only the electrical connections of the PV panels are changed while its physical location remains unchanged. To verify the effectiveness of the proposed reconfiguration technique, the system was simulated and tested using MATLAB/SIMULINK software, with four shading patterns. The results were compared with other reconfiguration techniques, namely TCT configuration, competence square (CS), SuDoKu, two-phase array reconfiguration, Genetic algorithm (GA), Particle Swarm Optimization (PSO), and Modified Harris Hawks Optimization (MHHO). The performance of each shading case was also analyzed. Also, a comparative study on performance analysis in real-time application was carried out for each shading pattern. The results prove the superiority of the proposed technique over other techniques for overcoming partial shading.
... The difference between the sum of the individual maximum power of the modules and the global maximum power point under partial shading conditions is the mismatch loss (Vijayalekshmy et al., 2016;Bingöl & Ö zkaya, 2018). Mismatch loss is computed by Eq. (6). ...
Article
Mismatch losses due to partial shading condition (PSC) is not permitted to extract maximum power from the solar PV array. Numerous techniques were proposed to reduce the partial shading effect. But the major problem is in finding out the occurrence and its distribution of the partial shading in the solar PV array. Conventional methods disconnect the load temporally from the PV array and measure the short circuit current (Isc) and use the information to detect the partial shading. Frequent disconnection of the solar PV array from the load makes the conventional method unpractical in a large solar power plant and even a stand-alone PV system. A novel on-time partial detection technique is proposed in this paper and useing difference in row voltage (Vd) instead of the short circuit current (Isc) to estimate the partial shading. Greater the Vd infers the severity of occurrence of the partial shading in the solar PV array. By using a static reconfiguration and then a modified couple matching (MCM) technique the voltage difference (Vd) gets reduced. This will ensure the mitigation of the PSC. As in this proposed technique, the load never be disconnected from the solar PV array, to detect the partial shading, it can be used practically even for a stand-alone PV system. Eight extensive partial shading patterns are simulated using MATLAB Simulink to validate the proposed work and the size of 3 × 4 120 W polycrystalline PV panel array is used for the experimental validation.
Article
Partial shade occurrences still prevail as a major obstacle for maximum power generation from photovoltaic (PV) power plants, particularly in urban areas. Therefore, augmenting the power output during such conditions has become a prerequisite in PV installations to guarantee reliable power conversion efficiency. In this context, PV array reconfiguration utilizing physical relocation techniques is a cost effective as well as promising solution. Though many such techniques have been developed in recent times, the applicability of those solutions to real-time power plants is questionable, predominantly due to: 1) incompatibility to unsymmetrical PV arrays, 2) impractical displacement of PV modules to distant columns, 3) necessity of large number of physical relocations, 4) need for lengthy interconnection ties and 5) non-availability of universal relocation rules. In this context, this paper proposes a new reconfiguration technique that can be applied globally irrespective of the size, type, and rating of PV arrays. In principle, the technique evolves from a mathematical concept to arrange PV modules diagonally along the opposite corners of the smallest rectangle that can be developed using squares. Graphically, the proposed technique emulates the vertical downward movement of knights in a chess board. More importantly, the relocation procedure is carefully designed such that each PV module in the array is relocated with in its respective column itself, thereby reducing the overall number of relocations required significantly. Distinctive from existing strategies, the proposed method can be applied to both unsymmetrical and symmetrical PV arrays without any arbitrary assumptions. For validation, extensive simulations considering numerous shade patterns as well as hardware experimentations have been carried out, and the results are compared with prominent techniques available in literature. The results attained show an average instantaneous power difference of 0.3 kW and 0.8 kW respectively for an 8.1kW system, compared with its counterparts and conventional interconnection schemes.
Conference Paper
Renewable energy sources are gaining broad popularity due to fossil fuel shortages and environmental issues caused by conventional sources of energy. Solar Photovoltaic energy is a widely used source of renewable energy. The power which a solar cell produces is greatly affected by the degree of insolation. Partial shading occurs when one or more photovoltaic (PV) cells receive less radiation than other cells, which in turn affects PV cells’ overall efficiency through decreased power generation. This paper proposes a Durer’s square based interconnection scheme for mitigating the losses and improving the generated power during partial shading conditions. Six different shading cases are simulated and it is found that the proposed approach provides a higher output as that of existing TCT, SP-TCT and Odd-Even configurations.
Article
Occurrence of partial shading and its high impact on the performance of photovoltaic (PV) system have received considerable attention during the last few years. It has forced the researchers to explore more novel PV array configurations to sustain under partial shading conditions (PSCs). To diminish the effects of PSCs, this paper presents an overview of the state-of-the-art developments of various PV array configuration models for PV systems. Different modeling approaches are analyzed while emphasizing their benefits and inadequacies. Different models available in the recent state-of-the-art literatures are studied and categorized according to vital configurations and features. Mainly, various PV array configurations such as advanced, futuristic configurations are also compared with the existing configurations. In this paper, recent research developments (that deserve further examination) are acknowledged and deliberated for the future researchers working in this domain.
Article
This paper reviews the existing models, connection schemes and maximum power point tracking (MPPT) methods of PV arrays. The partial shading causes significant power losses. It is very difficult to maintain uniform irradiance over the entire PV array, especially for rooftop or building-integrated PV systems. The aspects such as connection scheme of PV array, shading pattern and maximum power point tracking (MPPT) techniques, etc., decide the power generated by the PV array. The conventional MPPT methods are only capable of reaching maximum power point (MPP) in identical insolation situations. Hence, conventional MPP tracking becomes inept due to the existence of several peaks in the P-V characteristics. There are different global maximum power point (GMPP) tracking techniques available in the literature that operate in partial shading scenarios. The reconfiguration of the PV array reduces the number of multiple peaks. This reduction in several peaks makes conventional MPP tracking techniques competent even under partial shading conditions with low implementation complexity and higher tracking speed. This paper can assist scientists in choosing a precise objective-based PV module model, connection schemes and MPP tracking methods out of numerous schemes available in the literature.
Article
Varying solar radiation on photovoltaic (PV) panels reduces the PV system's output and increases the mismatch losses. Several techniques have been proposed to solve the mismatch problem, for example, the reconfiguration technique of PV panels. Most of the reconfiguration techniques have been proposed for small systems because of the difficulty in applying to large systems as a large number of switches are required for such applications. In this paper, a new technique based on total‐cross‐tied (TCT) in two reconfigurable stages is proposed. In the first stage, the shading over the PV plant is dispersed by switching between arrays. In the second stage, the shade dispersion from the first stage is increased by optimizing between the columns. The number of switches and sensors were reduced by using genetic algorithm, thus reducing the system cost. To demonstrate the proposed new reconfiguration technique, four shaded cases were simulated and tested using MATLAB/SIMULINK. A comprehensive analysis of power–voltage (P–V) curves and row currents calculation was performed, for TCT configuration and the proposed new reconfiguration technique. Also, a comparative study on performance analysis, energy‐saving, and income generation was carried out for each shading case. The comparative study of the four cases shows that the reconfiguration techniques proposed in two stages generate more power under partial shading conditions than TCT. Further research is needed to ensure the practicality of the switches needed to realize this technique. A new dynamic reconfiguration technique is proposed based on TCT in two reconfigurable stages, to disperse the shading over large scale of PV panels. The proposed reconfiguration results in reduced the number of switches and increased the generated power from the PV plant under shading conditions.
Article
Under partial shading conditions, the solar photovoltaic (PV) array receives an irregular pattern of solar light intensity which results in the creation of multiple peaks in the power vs voltage (P-V) and current vs voltage (I-V) plot and ultimately leads to hot spots creation and reduced power generation. Therefore, in this paper, redistribution of the shadow effect is assessed using a newly proposed reconfiguration method for the PV array called Contour Balancing Rearrangement (CBR) method. The proposed CBR method is based on the “Smash n’ Throw” approach which is applied to reconfigure the total-cross-tied (TCT) topology of the PV array that redistributes the shading pattern in such a way that the average irradiance of each row is almost the same. Further, a novel pragmatic dynamic cloud model is formulated to realize the partial shading condition as in realistic form at a particular location of the earth’s surface. For a more realistic analysis, the movement and acceleration of moving clouds are taken into account along with the coordinates of the place of interest for more accurate values of solar irradiation. Furthermore, different comparative studies are also carried out among the proposed and existing methods of various PV array reconfiguration methods to show the efficacy.
Article
This paper investigates the electrical behavior of total cross tied (TCT), SuDoKu (SDK) and killer-SDK (KSDK) configurations under several shading conditions. Three different types of bypass diode (BD) arrangements for these PV arrays (PVAs) have been reported and the considered different BD arrangements are without BD (WBD), non-overlapped BD (NBD) and overlapped BD (OBD). Due to the occurrence of shading situations, the investigation of excess current for various BD based PVA configurations has been carried out. In the present work, maximum prospecting values of excess current for PV modules and arrays are also reported. Moreover, comparative analysis between WBD, NBD and OBD based PVA configurations has been presented using P-V and I-V characteristics. Also, investigation has been extended in terms of reduction of excess current, power dissipation, power improvement, energy savings and earnings. The presented results may be used as a suggestion for appropriate BD interconnection for the chosen PVA configurations. Overall, it is reported in this article that the NBD based KSDK PVA configuration is superior to WBD, OBD and NBD based TCT and SDK PVA configurations.
Article
Maximum Power Point Tracking (MPPT) is an essential task when the solar photovoltaic (PV) system faces abrupt changes in light power or Partial Shading Condition (PSC). This paper proposes two distinctive optimization techniques, namely Particle Swarm Optimization (PSO) and Cuckoo Search (CS) for MPPT under PSC. Both techniques are tested under three different PSC patterns in MATLAB Simulink. Tracking efficiency of 99.86% and response time of 1.71ms were noted for PSO-based MPPT. Similarly, tracking efficiency of 99.84% and response time of 0.68ms were noted for CS-based MPPT. The proposed algorithms are experimentally validated concerning tracking speed, efficiency, complexity, and oscillations around Global MPP (GMPP). PSO method achieves 118.51% and 114.28% improvement in efficiency compared to P&O and IC, respectively. Similarly, the CS method achieves 118.53% and 114.29% improvement in efficiency compared to P&O and IC, respectively.
Article
Harvesting the optimal output from partially shaded PV arrays is a crucial issue. To address this, various reconfiguration techniques are reported in the literature. However, most of these techniques inherit numerous drawbacks such as compatibility issues, ineffective shade dispersal, numerous power peaks, inconsistent performance, increased mismatch, etc. Therefore, a novel reconfiguration approach based on Arnold’s Cat Map which is widely employed in image encryption is proposed in this work to overcome all the aforementioned issues. The proposed approach is tested for various symmetrical 9 × 9, 7 × 7, 6 × 6, 5 × 5, 4 × 4, and unsymmetrical 3 × 5, 4 × 3, 5 × 9, and 6 × 20 PV arrays under 100 shading cases. The performance of the proposed technique is compared with the 41 existing reconfiguration techniques for various array sizes. The proposed technique is experimentally validated in both indoor laboratory and outdoor environments for 4 × 4 and 3 × 5 PV arrays under distinct shading conditions. Further, to confirm the effectiveness and consistency of the proposed technique over the existing ones statistically, a Non-parametric Wilcoxon Signed-Rank test with a significant difference of 0.05 is considered for evaluation. The proposed technique yields the maximum enhancement in output by 30.81%, 36.36%, 38.15%, 33.77%, 16.62%, 21.8%, 18.42%, and 16.79% for 9 × 9, 7 × 7, 6 × 6, 5 × 5, 4 × 4, 4 × 3, 5 × 9, and 6 × 20 PV arrays respectively. From the comprehensive analysis, it is remarked that the lowest mismatch is obtained by the proposed encryption based-technique under all shading conditions.
Article
Non-homogenous irradiation levels across the solar PV array reduces the overall power yield of solar PV plant. Therefore, it is essential to decrease mismatch power loss incurred under non-homogenous conditions. For this purpose, ‘Lo Sho Square’ shade dispersion technique based re-configuration of solar PV modules is investigated in the present research work. Proposed ‘Lo Sho Square’ shade dispersion technique effectively scatters the non-homogenous irradiation across the reconfigured solar PV array, rather than concentrated on one location. Performance of the proposed re-configuration technique is studied by subjecting the 9 × 9 sized solar PV array under five different categories of non-uniform irradiation conditions. Efficacy of the proposed re-configuration is justified to be superior by comparing the simulation results obtained from proposed ‘Lo Sho Square’ technique with those obtained for Total-Cross-Tied interconnection and four recently reported ‘Normal SU-DO-KU’, ‘Optimized SU-DO-KU’, ‘Improved SU-DO-KU’ and ‘Modified SU-DO-KU’ shade dispersion techniques. The simulation results indicate that the proposed re-configuration scheme with values of 20%, 12.5%, 12.5%, 16.13% and 12.5% under five categories of typical non-homogenous conditions, has the lowest mismatch power loss relatively compared to that of literature reported four shade dispersion techniques. In addition, the proposed ‘Lo Sho Square’ technique based re-configuration with the efficiency values of 14.18%, 15.12%, 15.12%, 14.65% and 15.12% under five categories of typical non-homogenous conditions, has highest efficiency relatively compared to literature reported four shade dispersion techniques. Based on the comparative analysis of results obtained upon five typical non-homogeneous conditions, it is concluded that proposed ‘Lo Sho Square’ shade dispersion technique provides a relatively superior output performance compared to that of ‘Normal SU-DO-KU’, ‘Optimized SU-DO-KU’, ‘Improved SU-DO-KU’ and ‘Modified SU-DO-KU’ techniques.
Article
The susceptibility of solar photovoltaic (PV) modules towards partial shading is one of the major demerits encountered by PV arrays installed in the field. The partial shading among the modules leads to a serious reduction in the array power generation as it introduces several losses due to mismatch among modules. These power losses are mainly countered by implementing various electrical interconnecting configurations such as bridge-linked (BL), honeycomb (HC), and total-cross-tied (TCT) rather than using the conventional series-parallel (SP) connection. However, the configurations fail to generate maximum power during all partial shading scenarios. Hence, in this paper, a new module electrical reconfiguration technique is proposed to disperse the effect of partial shading power generation improvement and reduce the losses in the PV arrays. The technique is a one-time fixed electrical reconnection strategy for modules based on the algorithm proposed and requires no sensors and switches. The efficacy of the proposed electrical reconfiguration is investigated for two array sizes in MATLAB/Simulink and a real-time experimental environment whereas, the algorithm is programmed in the Python language. Also, a comparison is done with the conventional electrical configurations under various shading scenarios using the characteristics curves analysis, power generation, losses, efficiencies and performance ratio. The proposed reconfiguration enhances the power output of 26.92% than SP, 24.07% than BL, 25.17% than HC, and 22.96% than TCT during shading.
Chapter
Industries are concerned about mainly two issues after PV installation at site: PV degradation and partial shading. Because of mainly these two reasons the installed system is not able to give that much output power which it should give ideally as per the location's environment. But out of these two problems, partial shading is a frequent issue that further results in degradation of a PV system if proper measures are not taken. This chapter gives an overview of partial shading which includes its introduction and describes how irradiance is affecting the output parameters and performance of PV arrays. It also shares the causes and effect of partial shading in brief along with its classification. Many techniques have been discussed for the mitigation of this issue. This chapter mainly focuses on array reconfiguration methods which are elaborately described through their classification, methodology, and best‐suited configuration in each of their categories. As per the momentum situation, as a result of the long wire length prerequisite for PV cluster reconfiguration, the metaheuristic calculations are considered and generally acknowledged by specialists. Overall, the following chapter will be helpful for academics, industries, and researchers in the domain of partial shading for the PV arrays.
Article
Cases of partial shading cause unwanted effects on the output produced by the solar photovoltaic (PV). This is due to the fact that some modules in the array are covered by shade while others in the same array are not so. As a direct result of this phenomenon, multiple peaks arise in the P–V characteristics of the PV array (PVA) along with sudden and severe row current changes. Both of these impede the performance of PVAs. This paper involves four new approaches i.e. half-bridge link (HBL), half total cross tied (TCT) (HTCT), short arrangement alternative return, and addition progression structure (APS) pattern. In the APS PVA, the reconfiguration of classical TCT modules is done as per the APS puzzle pattern. The APS technique relocates the modules in the array without changing the electrical connections. The maximum output power, mismatch power loss, and fill factor of bridge link, series–parallel, TCT, honeycomb, HTCT, and HBL are compared with APS to analyse the performance of the reconfiguration technique proposed in this paper. The results establish the efficacy of the proposed APS method as it outperforms the conventional approaches deemed to be the most effective. The proposed APS topology provides a maximum reduction of 38.36% in mismatch power loss, and 1.62 more fill factor as compared to benchmark TCT configuration.
Article
Since the partial shading conditions easily bring a significant energy loss for a photovoltaic system, various array reconfiguration techniques have been proposed to improve the power generation efficiency. The existing studies of photovoltaic array reconfiguration mainly attempted to maximize the power output, which easily leads to a low total profit since they did not take the multi-period power fluctuation into account. In general, a large power fluctuation will result in a high regulation cost in a frequency regulation market, which can be smoothed by a hydrogen energy storage system. Consequently, this paper constructs a new multi-period photovoltaic array reconfiguration with a hydrogen energy storage system under partial shading conditions. It aims to maximize the total profit of photovoltaic system instead of only the power output by simultaneously consider the electricity selling profit in an electricity market, the hydrogen selling profit in a hydrogen market, and the regulation cost in a frequency regulation market. To address this problem, a novel efficient multi-agent negotiation algorithm with an auctioneer and multiple bidders is designed with the multi-round negotiation and the random re-initialization. The comprehensive case studies with a 10 × 10 total-cross-tied photovoltaic array shows that the proposed algorithm can acquire the higher total profit compared to five centralized meta-heuristic algorithms, in which the total profit can be increased from negative to positive against that without optimization under a discrete varying partial shading condition. Based on the simulation results, it can be concluded that the multi-period photovoltaic array reconfiguration can dramatically increase the total profit under a multi-market environment, while the proposed algorithm can achieve an efficient and distributed optimization under different partial shading conditions.
Article
Partial shading causes unwanted impact on the output produced by the photovoltaic arrays. This occurs because some modules in the array are covered by shade while others are not in the same array. As a result of this phenomenon, multiple peaks arise in the P–V characteristics of the photovoltaic array along with sudden and severe row current changes. Both factors impede the array performance. This manuscript presents a novel static reconfiguration technique (i.e., arithmetic sequence pattern configuration) and verifies it using an experimental work bench to reduce the shading effect on the array. This novel approach reconfigures the conventional total cross tied array in the arithmetic sequence pattern that helps to reduce the shading effect on a specific point and distributes it evenly across all the rows and increases the overall energy output. This manuscript examines and compares different techniques such as SuDoKu, futoshiki SuDoKu, improved SuDoKu, skyscraper SuDoKu and modified SuDoKu interconnections based on various factors like fill factor, mismatch power loss, efficiency, and global maximum power points. Finally, the present work concludes that the suggested arithmetic sequence pattern topology effectively reduces the shading effect and wiring losses. It provides better power output in reference to the other topologies. The proposed topology provides a maximum reduction of 37.98% in wire length as compared to skyscraper SuDoKu and minimum mismatch power loss of 594.8 W lesser as compared to the other configurations.
Article
An intractable but common problem in photovoltaic systems is that the power generated by photovoltaic will reduce seriously due to partial shading. In order to solve this problem, the photovoltaic array reconfiguration methods are developed to mitigate the impact of partial shading and increase output power. This work aims to undertake a comprehensive review on state-of-the-art photovoltaic array reconfiguration methods through a thoroughly investigation of 125 recently published papers. Compared with prior reviews, this work makes a more exhaustive classification, in which sixty-four methods are thoroughly categorized into nine groups. In addition, nine evaluation criteria are summarized for researchers to choose according to their specific requirements. Furthermore, a comprehensive comparison is provided based on ten specific indicators, such as monitor variables, complexity, response speed, rate of shadow dispersion, merits-demerits and application range, etc. Among these methods, the dynamic methods represented by meta-heuristic algorithms show more desirable performance than the static methods due to their faster response speed and prominent adaptability (e.g. the water cycle algorithm has the best performance with a power enhancement of 28%–37%, the TomTom algorithm has inferior performance with power enhancement of only 5%–25%). Finally, this review proposes six constructive suggestions and perspectives to offer technical inspirations for future research in the related fields.
Chapter
The impact of mismatch losses can be minimized by optimizing the interconnection configuration of a photovoltaic (PV) array. This paper proposes an interconnection using splitting technique to mitigate mismatch losses in an effective manner. This design consists of twenty-four PV modules in the arrangement of 4 × 6. The array is then split into three sub-groups (eight cells in each group) that has even number of rows and an optimum number of parallel branching. Series-parallel (SP), total-cross-tied (TCT) and the proposed interconnection are studied through modelling and simulations in MATLAB Simulink. The proposed interconnection generated 3594 W when not subjected to any shading. Next, cloud cover shading scenarios with different irradiation values are presented. In the first case study, the proposed interconnection delivered the highest output power, Pmp at 1700 W. This maximum output power is 44.1% and 38.9% higher than SP and TCT configurations. In the second case study, the proposed interconnection generated the highest output power at 2663 W which is 35.6% and 28.9% higher than both SP and TCT configurations. The results show that the proposed interconnection is the most favourable out of the three as it mitigated mismatch losses better than its counterparts.
Chapter
When there is non-uniform solar irradiation on a solar photovoltaic (PV) system, the output power will decrease due to mismatch effects because shaded cells produce lower current and voltage compared to non-shaded cells. Therefore, an adaptive method is designed to overcome this limitation which makes it suitable to be used as mobile system. Solar modules of the prototype are connected in total-cross-tied and sub solar cells in the solar modules are controlled by relay module which is programmed with an Arduino Uno. When a solar cell is shaded, the output voltage will decrease to set threshold value and sub cells will be activated to recover the voltage loss. Hence, the maximum output power of solar module is increased. MATLAB Simulink is used to simulate the designed solar module under various irradiance levels and partial shading conditions. The prototype measurement values and simulation result values are close with each other.
Article
Array reconfiguration techniques applied for partially shaded photovoltaic array yield maximum power output via row current minimization and shade dispersion. Both static and dynamic reconfiguration techniques are utilized for power maximization. Noticeable advantages like one time rearrangement, effective shade dispersion, and easy steps made physical or static more popular. With profound necessity to simplify the mathematical procedure and reduced complexity, in this work, a highly competent Column shift Right‐Left panel arrangement based array reconfiguration technique is proposed. It follows simple relocation steps to disperse even complex shade occurrences. To justify the versatility of the method, three different shade cases together with economy analysis and qualitative comparative study with five different existing methods including Total Cross Tied, Su Do Ku, Column method, Dominance Square, Improved Su Do Ku and Sky Scrapper methods are analysed. As a result of its implementation, power generation has aroused to a maximum of 13.47%, 4.35%, 14.01%, 9.97%, 3.45%, and 2.43%, for Top Left Corner shade case compared to conventional techniques. Further, economy analysis indicates that a maximum revenue is generated with proposed work. To strengthen the performance analysis, an experimental study on 3 × 3 PV array based on six performance metrics is carried out. For all the test cases conducted, an effective shade dispersion with the proposed method is achieved with the highest power output. The shade applied 3 × 3 Total cross Tied (TCT) and its respective shade dispersed arrangement following proposed method is illustrated. Further, the power delivered by both sets has been shown I the graph. It is clear that, the column based dispersed arrangement delivered a highest power of 112.13 W compared to TCT (65.58 W).
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Partial shading is a serious obstacle to effective utilization of photovoltaic (PV) systems since it result in significant output power reduction. PV array reconfiguration strategy is one of the most efficient used solutions to overcome negative effect caused by the partial shading in PV systems. This paper presents a comprehensive review of the major existing PV array reconfigurations approaches which are used to overcome the problem of partial shading. The different approaches are evaluated and compared according to their techniques, advantages and drawbacks. This work represents an interesting reference for researchers working in the field and a simple guide that serves as help for beginners on PV array reconfiguration.
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Nowadays, the proliferation of fossil fuels for power generation leads to their extinction besides damaging the environment to a larger extent. In order to strive for a better environment, the inclusion of renewable energy-based generation is the best substitute. Solar, wind, hydro, and biomass are the available renewable energy sources in nature. Among the list, solar-based PV power generation is the most promising one and yields the maximum power output. In spite of all postulates from PV, the dependency on the sun makes this power generation a bit complicated. The output power generated from the PV panel varies in accordance with the solar insolation, temperature, degree of inclination, and partial shading condition. For extracting the maximum power from the PV array, various configuration techniques are implemented such as series, parallel, series-parallel, TCT, and HC. But these configuration techniques are less effective during partial shading conditions (PSCs). In order to reduce the PSC effect, static reconfiguration of modules within the PV array is implemented. This paper reviews all novel reconfiguration-based techniques which are available in the literature till date. We have systematically classified various reconfiguration methodologies. This study provides the advancement in this area since some parameter comparison is made at the end of every classification, which might be a prominent base rule for picking the most gainful sort of reconfiguration method for further research. This review would be helpful for researchers in this field to select the most feasible reconfiguration method for their application, as this study reviews a considerable number of PV reconfiguration methods on one platform.
Article
Obtaining maximum power output even under adverse contributing factors is the main aim of all reconfiguration techniques that have been reported in literature. Although various attempt has been made to harness maximum energy via physical or electrical PV panel reconfiguration techniques. All these reconfiguration techniques increase the value of output power either by physical or electrical relocation of panel within a column or by placing it at a suitable position in the entire PV array. The placement of PV panel or reconnection of the PV panel at a new location is inspired by some optimization algorithm or by some pattern. This paper proposes a new reconfiguration scheme for maximum power output along with effective shade dispersion, lower voltage drops and lesser cost of cables. Paper also attempted to analyse the pragmatic aspect of PV modules connected under different reconfiguration schemes namely Series Parallel (SP), Total Cross Tied (TCT), Odd-Even (OE), Odd-Even-Prime (OEP), LU SHO, Sudoku etc. and evaluates the consequences of its applicability at field. Although the various reconfiguration scheme has reported to increase the output current and thereby the output power but the increase in capital cost of cables, voltage drop and power losses outweighs the increase in output current and power. Also, if the distance between the rooftop PV array and the location of the String Combiner Unit (SCU) is large, then loses will even be more. A comparative analysis of different reconfiguration techniques under various parameters is performed.
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The selection of proper encapsulation material plays a vital role in design and development of PV modules for achieving good performance. Characteristics of a selected PV module material show great impact on electric yield, long term durability, processing of modules and cost. A high thermal conductivity material removes the generated heat fast and it helps in reducing operating temperatures of PV modules there by improvement in electric yield. Proper material selection, partial shadings, solar irradiance, temperature, aging effect, etc. has high impact on the quality of PV systems. Certain cells or modules in a PV array are shadowed by passing clouds, trees, poles, buildings, bird droppings, and other objects in partial shading conditions (PSCs), also known as mismatch situations. Under PSCs, Total-Cross-Tied (TCT) PV array configuration generates more Global maximum Power (GMP) compared to other configurations like series-parallel, Honey-Comb and Bridge-Link. Total-Cross-Tied PV array configuration can be formed by connecting cross ties in between the strings to improve the global maximum power from PV array. In this paper, the performance analysis of mono crystalline, poly crystalline and thin film material based 6×6 T-C-T PV array topology under various partial shading conditions has been investigated. To check the efficacy of the material considered for the PV array, the performance measures like mismatch losses, fill factor, Global Maximum Power Point and conversion efficiency have been used.
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In this paper, a reformulation of the widely used one-diode model of the photovoltaic (PV) cell is introduced, employing the Lambert W function. This leads to an efficient PV string model, where the terminal voltage is expressed as an explicit function of the current, resulting in significantly reduced calculation times and improved robustness of simulation. The model is experimentally validated and then used for studying the operation of PV strings under partial shading conditions. Various shading patterns are investigated to outline the effect on the string I-V and P-V characteristics. Simplified formulae are then derived to calculate the maximum power points of a PV string operating under any number of irradiance levels, without resorting to detailed modeling and simulation. Both the explicit model and the simplified expressions are intended for application in shading loss and energy yield calculations.
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Partial shading of a photovoltaic array is the condition under which different modules in the array experience different irradiance levels due to shading. This difference causes mismatch between the modules, leading to undesirable effects such as reduction in generated power and hot spots. The severity of these effects can be considerably reduced by photovoltaic array reconfiguration. This paper proposes a novel mathematical formulation for the optimal reconfiguration of photovoltaic arrays to minimize partial shading losses. The paper formulates the reconfiguration problem as a mixed integer quadratic programming problem and finds the optimal solution using a branch and bound algorithm. The proposed formulation can be used for an equal or nonequal number of modules per row. Moreover, it can be used for fully reconfigurable or partially reconfigurable arrays. The improvement resulting from the reconfiguration with respect to the existing photovoltaic interconnections is demonstrated by extensive simulation results.
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Configuration of a photovoltaic (PV) power generator has influence on the operation of the generator, especially if it is prone to partial shading. In this paper, the mismatch losses and the power losses due to failure in tracking of the global maximum power point of a long string of 18 series-connected PV modules and three short strings of six series-connected PV modules connected in parallel are investigated under different partial shading conditions by using a MATLAB Simulink simulation model. The generators with parallel-connected short strings are studied in case when they have the same operating voltage and when they operate as separate strings. The results show that long series connection of modules and parallel connections of strings via a single inverter to the electrical grid should be minimized to avoid losses in case of partial shading conditions. Under partial shading conditions, short strings operating separately have the lowest power losses.
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1  Abstract— This paper proposes a deterministic PSO (DPSO) to improve the maximum power point (MPP) tracking capability for PV system under partial shading condition. The main idea is to remove the random number in the accelerations factor of the conventional PSO velocity equation. Additionally, the maximum change in velocity is restricted to a particular value, which is determined based on the critical study of P–V characteristics during partial shading. Advantages of the method include: (1) consistent solution is achieved despite a small number of particles (2) only one parameter i.e. the inertia weight, need to be tuned and (3) the MPPT structure is much simpler compared to the conventional PSO. To evaluate the idea, the algorithm is implemented on a buck-boost converter and compared to the conventional hill climbing (HC) MPPT method. Simulation results indicate that the proposed method outperforms the HC method in terms of global peak (GP) tracking speed and accuracy under various partial shading conditions. Furthermore, it is tested using the measured data of a tropical cloudy day, which includes rapid movement of the passing clouds and partial shading. Despite the wide fluctuations in array power, the average efficiency for the ten hours test profile reaches 99.5%. Index Terms— Direct control, global peak (GP), maximum power point tracking (MPPT), partially shaded, particle swarm optimization (PSO), photovoltaic (PV) systems.
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This paper applies a dynamical electrical array reconfiguration (EAR) strategy on the photovoltaic (PV) generator of a grid-connected PV system based on a plant-oriented configuration, in order to improve its energy production when the operating conditions of the solar panels are different. The EAR strategy is carried out by inserting a controllable switching matrix between the PV generator and the central inverter, which allows the electrical reconnection of the available PV modules. As a result, the PV system exhibits a self-capacity for real-time adaptation to the PV generator external operating conditions and improves the energy extraction of the system. Experimental results are provided to validate the proposed approach.
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In this paper, two factors typical of large photovoltaic (PV) arrays are investigated: one is the current-voltage (I-V) mismatch consequent to the production tolerance; the other is the impact of reverse currents in different operating conditions. Concerning the manufacturing I-V mismatch, the parameters of the equivalent circuit of the solar cell are computed for several PV modules from flash reports provided by the manufacturers. The corresponding I-V characteristic of every module is used to evaluate the behavior of different strings and the interaction among the strings connected for composing PV arrays. Two real crystalline silicon PV systems of 8 times 250 kW and 20 kW are studied, respectively. The simulation results reveal that the impact of the I-V mismatch is negligible with the usual tolerance, and the insertion of the blocking diodes against reverse currents can be avoided with crystalline silicon technology. On the other hand, the experimental results on I-V characteristics of the aforementioned arrays put into evidence the existence of a remarkable power deviation (3%-4%) with respect to the rated power, linkable to the lack of measurement uncertainty in the manufacturer flash reports.
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Solar photovoltaic (PV) arrays in portable applications are often subject to partial shading and rapid fluctuations of shading. In the usual series-connected wiring scheme, the residual energy generated by partially shaded cells either cannot be collected (if diode bypassed) or, worse, impedes collection of power from the remaining fully illuminated cells (if not bypassed). Rapid fluctuation of the shading pattern makes maximum power point (MPP) tracking difficult; generally, there will exist multiple local MPPs, and their values will change as rapidly as does the illumination. In this paper, a portable solar PV system that effectively eliminates both of the aforementioned problems is described and proven. This system is capable of simultaneously maximizing the power generated by every PV cell in the PV panel. The proposed configuration consists of an array of parallel-connected PV cells, a low-input-voltage step-up power converter, and a simple wide bandwidth MPP tracker. Parallel-configured PV systems are compared to traditional series-configured PV systems through both hardware experiments and computer simulations in this paper. Study results demonstrate that, under complex irradiance conditions, the power generated by the new configuration is approximately twice that of the traditional configuration. The solar PV system can be widely used in many consumer applications, such as PV vests for cell phones and music players.
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A procedure of simulation and modelling solar cells and PV modules, working partially shadowed in Pspice environment, is presented. Simulation results have been contrasted with real measured data from a commercial PV module of 209 Wp from Siliken. Some cases of study are presented as application examples of this simulation methodology, showing its potential on the design of bypass diodes configuration to include in a PV module and also on the study of PV generators working in partial shading conditions.
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To probe the sensitivity for localized heating of commercial amorphous silicon and crystalline modules, several intrusive and nonintrusive experiments were performed. In the intrusive experiments, each cell in several commercial amorphous silicon modules was evaluated separately and in groups for localized heating effects. Damage in amorphous silicon modules occurred under reverse-bias conditions in the dark above a 5-20 mAcm<sup>-2</sup> cell current density at the interconnection between cells. Shading can cause a larger temperature rise than current mismatch. For the monolithic amorphous silicon modules investigated, the current mismatch between each cell was substantial, but the temperature rise was negligible because of the rather low shunt resistance
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The many different techniques for maximum power point tracking of photovoltaic (PV) arrays are discussed. The techniques are taken from the literature dating back to the earliest methods. It is shown that at least 19 distinct methods have been introduced in the literature, with many variations on implementation. This paper should serve as a convenient reference for future work in PV power generation.
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Guidelines for the proper selection of solar array and battery sizes for use in photovoltaic-powered dispersed systems located far from public power networks are presented. The choice of key design parameters of separately excited DC motors used for farm irrigation is addressed. The selection procedure is based on accurate system modeling and annual simulation using actual meteorological and typical load data. The procedure determines the useful, dumped, and commercial energy components forced by system-load interaction. Two systems are investigated. System one is an AC residential load of a given annual demand profile on hourly basis, while system two represents an irrigation set-up featuring a DC motor and a battery back-up. The results show that a properly sized battery interface would enhance the performance of the irrigation system by more than 12% compared to the directly coupled case
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Without appropriate protection, partial shading of solar cell modules can have two undesirable effects. In the best case, partial shading can disproportionately reduce module output. In other cases, such shading can cause local overheating of the module, leading to module destruction. A simple technique which eliminates both problems is described. A bypass diode is integrated into the cell structure during cell processing with only one extra processing step required in representative processing sequences. The small associated cost is likely to be more than offset by increased module reliability, greater output in the field due to improved shadow tolerance, and simpler module assembly compared to discrete bypass diode approaches. The authors describe the underlying concepts, their experience producing such cells in pilot production quantities and the performance of solar cell modules and arrays incorporating these cells.
Conference Paper
This paper proposes a novel global maximum power point tracking (MPPT) strategy for solar photovoltaic (PV) modules under partial shading conditions using a dynamic particle swarm optimisation (PSO) algorithm. Solar PV modules have non-linear V-P characteristics with local maximum power points (MPPs) under partial shading conditions. In order to continuously harvest maximum power from solar PV modules, it always has to be operated at its global MPP which is determined using the proposed dynamic PSO algorithm. The obtained simulation results are compared with MPPs achieved using the standard PSO, and Perturbation and Observation (P&O) algorithms to confirm the effectiveness of the proposed algorithm under partial shading conditions.
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The development of photovoltaic (PV) energy throughout the world this last decade has brought to light the presence of module mis-match losses in most PV applications. Such power losses, mainly occasioned by partial shading of arrays and differences in PV modules, can be reduced by changing module interconnections of a solar array. This paper presents a novel method to forecast existing PV array production in diverse environmental conditions. In this approach, field measurement data is used to identify module parameters once and for all. The proposed method simulates PV arrays with adaptable module interconnection schemes in order to reduce mismatch losses. The model has been validated by experimental results taken on a 2.2 kW p plant, with three different interconnection schemes, which show reliable power production forecast precision in both partially shaded and normal operating conditions. Field measurements show interest in using alternative plant configurations in PV systems for decreasing module mismatch losses.
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This paper presents simulation and hardware implementation of incremental conductance (IncCond) maximum power point tracking (MPPT) used in solar array power systems with direct control method. The main difference of the proposed system to existing MPPT systems includes elimination of the proportional-integral control loop and investigation of the effect of simplifying the control circuit. Contributions are made in several aspects of the whole system, including converter design, system simulation, controller programming, and experimental setup. The resultant system is capable of tracking MPPs accurately and rapidly without steady-state oscillation, and also, its dynamic performance is satisfactory. The IncCond algorithm is used to track MPPs because it performs precise control under rapidly changing atmospheric conditions. MATLAB and Simulink were employed for simulation studies, and Code Composer Studio v3.1 was used to program a TMS320F2812 digital signal processor. The proposed system was developed and tested successfully on a photovoltaic solar panel in the laboratory. Experimental results indicate the feasibility and improved functionality of the system.
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A new method for estimating the irradiance on a partially shaded photovoltaic generator system is proposed. The basic principle of this method consists of two parts: firstly, an approximation of the obstacles’ outline or the local horizon by a set of linear functions. Here, a survey of the surroundings is based on the reading of the topographic coordinates of the only significant points of all the objects surrounding the photovoltaic generator. Secondly, the irradiance on the photovoltaic plane is estimated using an accurate model such as the Perez et al. model and assuming that the shading affects both the direct radiation and a part of the diffuse component (circumsolar component).The aim of this paper is to present the principles of the proposed method and the algorithm used for calculating the irradiance on shaded planes. In addition, the results of the comparison between the simulated and measured values of this method are presented.
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The operational lifetime of large solar PV arrays is investigated using the probability theory for the assessment of reliability. Arrays based on the following three solar cell interconnection schemes have been considered: (i) simple series-parallel (SP) array, (ii) the total-crossed-tied (TCT) array which is obtained from the SP array by connecting ties across each row of junctions and (iii) the bridge-linked (BL) array in which all cells are interconnected in bridge rectifier fashion. To evaluate the reliability of the bridge-linked configuration, the cut-set technique is used. Computational results based on arrays consisting of (720×20) solar cells indicate that the operational life of an array is almost doubled by the introduction of cross ties (TCT or BL schemes) in the array. The operational lifetime can be further increased by ∼30% by modularized networks based on TCT and BL configurations. These results are based on a theoretical analysis, however, and not on measured efficiency and life expectancy of solar cells.
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A Pascal program, PVNet, has been developed at the Commission of the European Communities Joint Research Centre, Ispra, to model the electrical behaviour of solar cell interconnection circuits. The program calculates three-quadrant solar cell current-voltage (I–V) curves using a lumped parameter equivalent circuit model, combines them to obtain the resultant I–V curve of any interconnection circuit, and calculates the operating point of each circuit element, set by user-defined operating conditions. The numerical values of the equivalent circuit parameters are generated by the program, and are varied so that the electrical parameters (short-circuit current, open-circuit voltage, fill factor) of calculated I–V curves show the same variations as those of measured crystalline silicon solar cell I–V curves. Equivalent circuit parameters can be changed by the user, making it possible to simulate the effects of electrical mismatches on the performance of an interconnection circuit. To illustrate the operation of the program, the electrical mechanisms leading to hot-spot heating in photovoltaic arrays are analysed. Three types of interconnection circuit are considered: a simple series string, a series-parallel block and a series connection of series-parallel blocks. The operation of parallel bypass diodes (used to limit hot-spot heating in series strings) and of series blocking diodes (used to prevent current imbalance in series-parallel circuits) are explained.
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The performance of a photovoltaic (PV) array is affected by temperature, solar insolation, shading, and array configuration. Often, the PV arrays get shadowed, completely or partially, by the passing clouds, neighboring buildings and towers, trees, and utility and telephone poles. The situation is of particular interest in case of large PV installations such as those used in distributed power generation schemes. Under partially shaded conditions, the PV characteristics get more complex with multiple peaks. Yet, it is very important to understand and predict them in order to extract the maximum possible power. This paper presents a MATLAB-based modeling and simulation scheme suitable for studying the I-V and P-V characteristics of a PV array under a nonuniform insolation due to partial shading. It can also be used for developing and evaluating new maximum power point tracking techniques, especially for partially shaded conditions. The proposed models conveniently interface with the models of power electronic converters, which is a very useful feature. It can also be used as a tool to study the effects of shading patterns on PV panels having different configurations. It is observed that, for a given number of PV modules, the array configuration (how many modules in series and how many in parallel) significantly affects the maximum available power under partially shaded conditions. This is another aspect to which the developed tool can be applied. The model has been experimentally validated and the usefulness of this research is highlighted with the help of several illustrations. The MATLAB code of the developed model is freely available for download.
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A technique is presented to improve the performance of a photovoltaic (PV) powered permanent magnet DC motor coupled to a screw-type volumetric water pump. The method uses a solid-state electric array reconfiguration controller (EARC), which senses the radiation as low, medium, or high. The controller chooses one favorable set of I - V characteristics for starting and another favorable set of I - V characteristics for steady-state operation. This is done by switching the solar panels, depending upon the starting current requirements and the irradiance level, from a parallel to series-parallel to series connection. This produces a sufficient starting current, especially at low and medium radiation levels, which considerably improves the pump's performance, particularly in the early morning, in the late evening, and on cloudy days, providing valuable extra pumping hours for the user
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Over the past three years, the New Mexico Solar Energy Institute (NMSEI) has tested and collected data on eight intermediate-size flat-plate photovoltaic systems. These data are now included in a valuable database for determining component reliability and system degradation trends. The specific test techniques used by NMSEI and the reliability of photovoltaic modules revealed by this testing are described and discussed. These methods are: I-V curve plotting, operating voltage and current measurements, and shading tests. These use of I-V curve data are important in determining array peak power rating and quickly locating large system faults. Operating voltage and current measurements are used in determining the location of module level faults. Bypass diode current measurements in conjunction with intentional module shading are used for isolating module faults in intermediate-size systems and systems with inaccessible module wiring. Of the 64000 modules tested, 362 modules (0.6%) were not contributing power
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This paper proposes an adaptive reconfiguration scheme to reduce the effect of shadows on solar panels. A switching matrix connects a solar adaptive bank to a fixed part of a solar photovoltaic (PV) array, according to a model-based control algorithm that increases the power output of the solar PV array. Control algorithms are implemented in real time. An experimental reconfiguration PV system with a resistive load is presented and is shown to verify the proposed reconfigurations.
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Current-voltage and power-voltage characteristics of large photovoltaic (PV) arrays under partially shaded conditions are characterized by multiple steps and peaks. This makes the tracking of the actual maximum power point (MPP) [global peak (GP)] a difficult task. In addition, most of the existing schemes are unable to extract maximum power from the PV array under these conditions. This paper proposes a novel algorithm to track the global power peak under partially shaded conditions. The formulation of the algorithm is based on several critical observations made out of an extensive study of the PV characteristics and the behavior of the global and local peaks under partially shaded conditions. The proposed algorithm works in conjunction with a DC-DC converter to track the GP. In order to accelerate the tracking speed, a feedforward control scheme for operating the DC-DC converter is also proposed, which uses the reference voltage information from the tracking algorithm to shift the operation toward the MPP. The tracking time with this controller is about one-tenth as compared to a conventional controller. All the observations and conclusions, including simulation and experimental results, are presented.