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In photovoltaic systems, parasitic capacitance is often formed between PV panels and the ground. Because of the switching nature of PV converters, a high-frequency voltage is usually generated over these parasitic capacitances; this, in turn, can result in a common-mode current known as leakage current. This current can badly reach a high value if a resonance circuit is excited through the PV's parasitic capacitance and the converter's inductive components. Transformers are usually used for leakage current mitigation. However, this decreases the efficiency and increases the cost, size, and weight of the PV systems. Number of strategies have been introduced to mitigate the leakage current in transformer-less converters. Among these strategies, using common-ground converters is considered the most effective solution as it offers a solid connection between the negative terminal of PV modules and the neutral of the grid side; thus, complete mitigation of the leakage current is achieved. Number of common-ground inverters have been recently presented. These inverters are different in their size, cost, boosting capability, the possibility of producing DC currents, and their capability to offer multilevel shaping of output voltage. This work introduces a comprehensive review and classification for various common-ground PV inverters. Therefore, a clear picture of the advantages and disadvantages of these inverters is clarified. This provides a useful indication for a trade-off between gaining some of the advantages and losing others in PV systems. In addition, the potentials for optimization based on different performance indicators are identified. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes three‐phase microinverter able to process the power of three PV modules simultaneously and independently; thus, efficient utilization of PV modules through distributed maximum power point tracking (DMPPT) is realized. The proposed microinverter employs switched capacitors (SCs) networks combined with three‐phase voltage source inverter; it is named switched capacitor buck‐boost voltage source inverter and abbreviated as SC‐BBVSI. The connections of SCs networks are determined to fulfill the high boosting gain along with minimized leakage currents. In addition, low capacitances values can be employed for power decoupling purpose. Thus, in addition to DMPPT feature, three features of high boosting gain, high‐reliable product, and minimized leakage current are realized without using the bulky and costly isolation transformer. In this paper, the operation modes of SC‐BBVSI for single and multi‐input scenarios are explained. The modulation strategy to realize these modes along with the control system design is presented as well. The relations required to design the passive elements and identify the device's stresses are derived. The features of the proposed microinverter are confirmed through detailed comparison with other recently reported topologies. Both simulation and experimental results are provided to verify the features of the proposed topology. [ABSTRACT FROM AUTHOR]

This paper presents a detailed study of Photovoltaic (PV) system performance under desert environmental effects in order to maximize the captured energy of PV system. The proposed study mainly focused on the output power loss of the PV system due to dust accumulation to determine the optimum tilt angle. Eight PV panels were installed on the roof of Faculty of Engineering, Upper Egypt-located in desert environment, at 15°, 20°, 30° and 45° tilt angles with the intention to analyze and compare the performance of the cleaned and dusty solar panels. The output power is recorded for cleaned and dusty solar panels with different tilt angles through the test period. Also, the effect of the panel surface temperature is experimentally studied. The measured data shows that the dust accumulation on the surface of the solar panels reduces the output power. The reduction ratio depends on the number of uncleaned days and tilt angle. The reductions in the output power for dusty panels after ten months of dust accumulation are 43%, 38%, 31%, and 25.5% for tilt angles of 15°, 20°, 30° and 45°, respectively. Also, the optimum tilt angle that gives maximum average output power depends on number of uncleaned days for the dusty panels. On the other hand, the optimum tilt angle for cleaned panels is mainly depends on the season variations. An empirical formula for the output power reduction of the solar panel is proposed and validated to illustrate the correlation between the numbers of dust accumulation days and tilt angle. It helps solar panel system designers to accurately predict the amount of solar power reduction and optimum tilt angle for a specified cleaning schedule. [ABSTRACT FROM AUTHOR]

In this article, a new single-stage high boosting ratio converter for grid-connected photovoltaic systems is proposed. The proposed system consists of a high voltage gain switched inductor buck-boost inverter that employs a folded cascade H-bridge circuit and operates at line frequency. The proposed system has a single switch operated with a sine wave modulation control. This applied control achieves maximum power point tracking of the input photovoltaic system in addition to the required injected sinusoidal grid current. The proposed system achieves the highest voltage boosting ratio of transformer-less topologies to the authors' best knowledge—more than ten times. In addition, it lowers switching losses and reduces the ground leakage current. A 150-W prototype with input voltage of 20 V and output voltage of 240 V has been developed with the purpose of obtaining experimental results and validating the proposed topology. Results report a boosting voltage gain of about ten times and system efficiency above 85%. [ABSTRACT FROM AUTHOR]

Microinverters are an essential part of the photovoltaic (PV) industry with significant exponential prevalence in new PV module architectures. However, electrolyte capacitors used to decouple double line frequency make the single-phase microinverters topologies the slightest unit in this promising industry. Three-phase microinverter topologies are the new trend in this industry because they do not have double-line frequency problems and they do not need the use of electrolyte capacitors. Moreover, these topologies can provide additional features such as four-wire operation. This paper presents a detailed discussion of the strong points of three-phase microinverters compared to single-phase counterparts. The developed topologies of three-phase microinverters are presented and evaluated based on a new classification based on the simplest topologies among dozens of existing inverters. Moreover, the paper considers the required standardized features of PV, grid, and the microinverter topology. These features have been classified as mandatory and essential. Examples of the considered features for classifications are Distributed Maximum Power Point Tracking (DMPPT), voltage boosting gain, and four-wire operation. The developed classification is used to identify the merits and demerits of the classified inverter topologies. Finally, a recommendation is given based on the classified features, chosen inverter topologies, and associated features. [ABSTRACT FROM AUTHOR]

• Dual-input split-source inverter (DSSI) is proposed for PV systems. • Compared to using one inverter per PV source, DSSI offers lower cost, and size. • DSSI offers independent and efficient maximum power points tracking. • Low capacitance value can be utilized for power decoupling. • Experimental and simulation results are provided to verify the operation of DSSI. This paper proposes dual-input configuration of split-source inverter (abbreviated as DSSI) to transfer the power of two photovoltaic (PV) modules simultaneously or individually. The proposed DSSI keeps the continuity of the input current and the voltage boosting capability offered by the conventional split-source inverter (SSI). Thus, independent as well as efficient tracking of the maximum power points (MPPs) is realized. In addition, low capacitance is utilized for power decoupling in single-phase circuits. Compared to using one SSI per PV source to feed a common load, the proposed DSSI uses lower number of switches at reduced total volt-ampere stresses. Therefore, decreased cost, size, and control circuitry are realized. Simple unipolar modulation technique is presented. Accordingly, the modes of operation and the Volt-ampere stresses of the switches are explained. A closed loop control system is explained to fulfill operation at MPP along with regulation of DC-link voltage and load current. Comparative study with other dual-input topologies is presented. Experimental results as well as real-time simulation results for dual- and single-input scenarios are presented. Also, the dynamic performance under step change in the radiation is investigated. Finally, the capability of operation under different power factors is verified. [Display omitted] [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) solar systems with series-connected module integrated converters (MICs) are receiving increased attention because of their ability to create high output voltage while performing local maximum power point tracking (MPPT) control for individual solar panels, which is a solution for partial shading effects in PV systems at panel level. To eliminate the partial shading effects in PV system more effectively, sub-MICs are utilized at the cell level or grouped cell level within a PV solar panel. This study presents the results of a series-output-connection MPPT (SOC-MPPT) controller for sub-MIC architecture using a single sensor at the output and a single digital MPPT controller (sub-MIC SOC-MPPT controller and architecture). The sub-MIC SOC-MPPT controller and architecture are investigated based on boost type sub-MICs. Experimental results under steady-state and transient conditions are presented to verify the performance of the controller and the effectiveness of the architecture. [ABSTRACT FROM AUTHOR]