The photovoltaic (PV) Power generation is the best source of renewable energy due to advantages such as free fuel cost, cleanness, little maintenance, and causing no noise due to absence of moving parts. Egyptian government moves towards encourage consumers to generate electricity from PV array and issues new electricity law that allow consumers to sell the surplus of the generated power of PV to utility. partial shading is one of the obstacles of the propagation of the electricity generation by PV array. partial shading may be occurs due to clouds, trees and neighbor building. This paper propose a new method for optimization of power of a rooftop photovoltaic (PV) array connected to grid under partial shading. This work provides a comparative literature review on methods to mitigate these effects and the drawbacks of this method. This paper represent the components of the interconnection between the rooftop PV array and the grid. The Maximum power point (MPP) achieved by perturb and observe technique which control the duty cycle of the buckboost converter. The proposed technique increased the output power of the PV and output efficiency during the partial shading condition.

Most of the partial shading maximum power point tracking methods have been designed for the static shading pattern of the partial shading conditions, however, the irradiance pattern may change further when in partial shading mode. Therefore, to cover this research gap, a global maximum power point control under varying irradiance (GCVI) algorithm is proposed in this paper. The algorithm does not use any sensors to detect the change in the irradiance, instead, the change in the current values of the modules are continuously monitored to detect the change. The reference voltages across which the peaks on the power curve are scanned are obtained from the reference voltage generation process, the consideration of these reference points avoids the excessive power losses in the system. The verification of the working of the proposed algorithm is carried out by simulating the photovoltaic system model on SIMULINK in MATLAB software. Simulations are carried out in various scenarios to show the effectiveness of the control. The simulation results illustrate that with the change in the global maximum under partial shading, the system successfully retunes to the new maximum point; the maximum point retunes from 10 kW to 9.2 kW and from 13.8 kW to 11.5 kW for two different case scenarios. Further, the comparisons are also carried out with the previously reported methods.

Photovoltaic (PV) systems have been gaining great attention during the last decade. One of the main faults in PV arrays is partial shading, affecting its electrical parameters. Failure to detect this fault may result in optimal generated power reduction and hot spotting leading to damage to cell encapsulant and second breakdown. This paper develops a partial shading detection algorithm that only requires the available measurements of array voltage and current. By quantifying the wave-shape of the super-imposed component of PV array power by the skewness function, it can discriminate a partial shading condition from the short-circuit and high-resistance faults. The developed scheme is implemented in a central intelligent electronic device and does not require a communication link and training data set. The merits of the proposed partial shading detection algorithm are demonstrated through several fault scenarios using a 5×5 grid-connected PV generation system.

Given the increasing popularity of solar energy and producing its accessory equipment in Iran, like DC/DC converters, and since for studying and comparing converter’ s performance or developed algorithms to extract the maximum power from converter, it is necessary to test it under uniform conditions, but due to various interfering factors such as hourly, daily, and spatial variation of solar radiation intensity or unpredictable shading on panels, the tests have to be performed using a simulator. Therefor this paper derives a new set of relations to simulate the panel’ s performance under partial shading conditions and a simulator is constructed accordingly. By holding the temperature constant, the converter’ s performance is studied for both uniform illumination and partial shading conditions. Result of studies carried out for uniform illumination under standard conditions and partial shading in conditions under which one third of cells received 600 w/m2 and the rest received 1000 w/m2, indicated a good agreement between the converter’ s performance and ideal I-V and P-V curves of solar panel.

In this paper, a new two-stage control algorithm to reach the maximum power point in photovoltaic (PV) systems under partially shaded conditions is presented. This algorithm tracks the maximum power point without any need to measure the open circuit voltage, short circuit current and making use of any extra switches. To achieve maximum power performance, the method firstly selects the relevant region of maximum power point based on received radiations from solar panels. After finding the correct power region, the accurate point of maximum power is reached by applying P&O method. Using this algorithm decreases the costs and also finds the MPP with more speed and accuracy at the first cycle. Performance validation of the proposed algorithm, is performed by running simulation on a typical system. The simulation results show the superior performance of the proposed approach in comparison with the conventional methods.

Climate change and ever-increasing water consumption, along with water scarcity, reduces crop production. Thus, such efficient water management, as deficit irrigation as well as shading could be the answer to some of these shortcomings. In deficit irrigation practice with partial Root zone Drying (PRD), half of the root zone is irrigated and the other half is left dry. This experiment was conducted involving five treatments of (1) full irrigation, in which trees received 100 percent water content of soil field capacity (FC), 2) two PRD treatments, namely receiving 50 (PRD50) and 75% (PRD75) of FI, and 3) two PRD treatments, as above treated by shading nets (SHPRD50 and SHPRD75). Tukey's test was employed to compare the treatment’ s means of stomatal conductance (gs), leaf relative water content (rwc), stem water potential (Ψ st), and leaf temperature (Tl). Moreover, Regression analysis was carried out among the above factors and leaf vs air vapor pressure difference. The results show that gs and rwc were higher in FI, PRD75 and SHPRD75 relative to the stressed treatments of PRD50 and SHPRD50. The same trend was registered for Ψ st, the lowest values being achieved by treatments receiving 50% FI. Leaf temperatures in some measurement intervals were significantly higher in stressed treatments of PRD50 and SHPRD50. Water deficiency significantly reduced yield in stressed treatments of PRD50, while in reverse, it increased fruit soluble solids in PRD50 and PRD75. shading on PRD treatments increased fruit size and yield, although this improvement was significant only for fruit diameter in SHPRD75 in comparison with PRD50.

Maximum Power Point Tracking (MPPT) is an important concept for both uniform solar irradiance and partial shading conditions (PSCs). The paper presents an Improved Salp Swarm Algorithm (ISSA) for MPPT under PSCs. The proposed method benefits a fast convergence speed in tracking the Maximum Power Point (MPP), in addition to overcoming the problems of conventional MPPT methods, such as failure to detect the Global MPP (GMPP) under PSCs, getting trapped in the local optima, and oscillations around the MPP. The proposed method is compared with original algorithms such as Perturbation and Observation (P&O) method (which is widely employed in MPPT applications), Differential Evolutionary (DE) algorithm, Particle Swarm Optimization (PSO), and Firefly Algorithm (FA). The obtained results show that the proposed method can detect and track the MPP in a very short time, and its accuracy outperforms the other methods in terms of detecting the GMPP. The proposed ISSA algorithm has a higher speed and the convergence rate than the other traditional algorithms.

The performance of photovoltaic (PV) systems is highly dependent on environmental conditions. Due to probable changes in environmental conditions, the real-time control of PV systems is essential for exploiting their maximum possible power. This paper proposes a new method to track the maximum power point of PV systems using the moth-flame optimization algorithm. In this method, the PV DC-DC converter’ s duty cycle is considered as the optimization parameter, and the delivered power of the PV system is maximized in real time. In the proposed approach, some schemes are also employed for detecting condition changes and ignoring small fluctuations of the duty cycle. The results of performance evaluation confirm that the proposed method is very fast, robust, and accurate in different conditions such as standard irradiance and temperature, irradiance and temperature variations, and partial shading conditions. The obtained steady-state efficiency and response time for the introduced method under the standard conditions of the test PV system are 99. 68% and 0. 021 s, respectively. Indeed, in addition to a relatively good efficiency, the faster response of the introduced tracker is also evident in comparison with other methods.