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The main objective of this work is to evaluate the energy efficiency improvement obtained in grid-connected photovoltaic systems based on a dynamic reconfiguration strategy. The MIX and team reconfigurable photovoltaic system topologies have been considered since both minimize the operation of the inverters in low-load conditions. A numerical method is used to analyze the energy flows within the photovoltaic system, with a specific focus on the plant-oriented configuration. In this work, MIX systems are only presented briefly, while team reconfigurable photovoltaic systems are analyzed in more detail. This is because team systems can be implemented using conventional commercial inverters, electromechanical switches to redirect power flows, and a simple digital controller (as based on the Arduino platforms). The energy supplied to the grid by two grid-connected photovoltaic systems will be evaluated: one based on a classic non-reconfigurable strategy and another based on the team strategy. The measurement of the energy generated by these two systems, tested under various irradiance levels (emulating different climatic conditions), shows that reconfigurable systems always exhibit greater energy efficiency. However, this energy improvement can only be considered substantial in certain situations. [ABSTRACT FROM AUTHOR]

Grid-connected photovoltaic systems have been widely utilized as means of renewable energy-based electricity supply worldwide. Nevertheless, one of the major issues in their implementation is optimal system design, also associated to system sizing. An undersized or oversized system components could compromise the technical benefits of the systems. Therefore, this paper discusses a Grey Wolf Optimization (GWO) for optimizing a grid-connected photovoltaic system design. The optimization problem was devised based on single objective optimization with models of photovoltaic module and inverter set as the decision variables and specific yield transcribed as fitness value that needs to be maximized. Before optimization, an iterative-based sizing algorithm was formulated to determine the optimal module and inverter that give the highest specific yield using a non-computational intelligence approach. Later, GWO was employed to determine the maximum specific yield by choosing the optimal model of PV module and inverter. The results showed that GWO was able to produce same specific yield obtained by iterative-based sizing algorithm. Additionally, GWO was observed to be about 11.3 times faster when compared with the iterative approach. When comparing with particle swarm optimization and genetic algorithm, GWO was discovered to produce higher specific yield with relatively similar computation time.

A grid-connected photovoltaic (GCPV) system plays an important role in the development of green technology. However, generated photovoltaic (PV) power that is injected into the grid causes instability in the grid system. Previous studies have shown that power quality for a three-phase system is thoroughly being discussed, but not for a single-phase system. Single-phase system also contribute to instability in low-voltage grid networks during high power penetration as majority of the single-phase GCPV nowadays are installed on rooftops. Thus, in this study, the power quality of a single-phase single-stage GCPV system is investigated based on the total harmonic distortion (THD), power factor (PF), and the generated active (P) and reactive (Q) power during different solar irradiance and varying loads conditions. A model of the GCPV system was developed in MATLAB/Simulink, so that certain variables can be varied to observe their effect towards the power quality. The results show that the current and voltage of generated PV power are synchronized and having low current THD which is less than 1% for all cases. PF values are also in the acceptable range in compliance to IEC 61727 standard which is 0.9971, and the generated PQ is in accordance to the connected load. [ABSTRACT FROM AUTHOR]

The main objective of this work is to evaluate the energy efficiency improvement obtained in grid-connected photovoltaic systems based on a dynamic reconfiguration strategy. The MIX and team reconfigurable photovoltaic system topologies have been considered since both minimize the operation of the inverters in low-load conditions. A numerical method is used to analyze the energy flows within the photovoltaic system, with a specific focus on the plant-oriented configuration. In this work, MIX systems are only presented briefly, while team reconfigurable photovoltaic systems are analyzed in more detail. This is because team systems can be implemented using conventional commercial inverters, electromechanical switches to redirect power flows, and a simple digital controller (as based on the Arduino platforms). The energy supplied to the grid by two grid-connected photovoltaic systems will be evaluated: one based on a classic non-reconfigurable strategy and another based on the team strategy. The measurement of the energy generated by these two systems, tested under various irradiance levels (emulating different climatic conditions), shows that reconfigurable systems always exhibit greater energy efficiency. However, this energy improvement can only be considered substantial in certain situations.

In grid-connected PV systems, the inverter is one of the important components. Inverter efficiency may vary depending on the input power and voltage of the PV array. This paper analysed three factors affecting inverter efficiency. The first one was the effect of the duration of inverter operations. Analysis of the operation of a PV system that has been operating four years showed an annual average inverter efficiency of 0.90, almost equal to the manufacturer’s specification of 0.91. The study showed that there was no significant degradation in inverter efficiency because a cool temperature (of 25°C) was maintained for the inverter storage room through an air conditioning system. The second analysis investigated the effect of the power input from different types of PV module technology. The study showed that the inverter connected to p-Si PV modules operated the highest efficiency at 0.91. However, detailed analyses showed that PV module technology had less or minimal impact on inverter efficiency. It was the power input from the PV module that has influence on the inverter efficiency. The third analysis involved the study of the effect of irradiance distribution on inverter efficiency. The study shows that the inverter operates at the maximum efficiency of 0.90 at irradiance of above 350 W/m2, at which range solar energy potential is at its highest at around 85% of the total generation. This means that inverter converts almost all the energy supplied from solar PV at this irradiance range. In conducting the third analysis, a location-specific equation, ηPHS,for determining inverter efficiency was also developed. The ηPHSequation generates the actual inverter efficiency values based on the local irradiance conditions in Phitsanulok province.

Grid-connected photovoltaic systems have become the most important and popular use of the solar energy. In this paper, a photovoltaic system connected to a three-phase network is presented. The system is connected in a single step using a five-stage voltage source inverter to improve the quality of the power in the distribution system. The control strategy applied for the optimal operation of the photovoltaic system is based on the theory of instantaneous reactive power. This strategy is simple and has the advantage of running the system all day without using Phase-Locked Loop (PLL). The multilevel inverter switching signals are derived from the Pulse Width Modulated Current Controller, which provides good dynamic performance in both steady state and transient conditions. The voltage of the continuous bus capacitors is controlled using the PI controller. The validation of this proposed system is carried out through simulation with different levels of irradiations and by a comparison with the performance of a two-level inverter used in the original configuration. This specific configuration shows good results regarding the waveforms of the voltages and the output currents as well as the level of the quality of the energy represented in this paper by the THD parameter that has been studied in comparison with the two-level converter. [ABSTRACT FROM AUTHOR]

In this study, novel control schemes are developed for cooperative control of stand‐alone and grid‐connected photovoltaic (PV) based water pumping system. Brushless DC motor is used as pumping motor due to its superior characteristics. The cooperative control effectively utilises the available resources. In stand‐alone system, control scheme is developed for power sharing among PV pumping units. Assuming some of the PV units have battery, the charging/discharging controller is incorporated. In grid‐connected system, flexible control scheme is proposed so that consumer can draw lesser power from grid by running the motor at lower speed instead of rated speed. In case of high PV power penetration into weak grid, the modified perturb and observe algorithm is proposed for sharing of de‐loaded power among the PV units. Due to de‐loading of PV power, motor speed reduces, hence, speed compensation mechanism is developed to bring back the speed at desired value. As a futuristic concept, consumer can buy power from neighbour instead of taking from grid. To establish above‐mentioned concept, control scheme is developed for sharing the power among PV pumping units. The simulation and hardware results are carried out to test performance of the proposed control schemes. [ABSTRACT FROM AUTHOR]

This study expounds how a reverse osmosis desalination system coupled to a photovoltaic system connected to the grid (hybrid PV-Grid) can be a sustainable option in satisfying the increasing fresh water demand in Algeria and worldwide. A feasibility analysis of the technical, economic and environmental potential of the grid-connected photovoltaic (PV) energy system to electrify seawater desalination station in Algeria is investigated. A seawater reverse osmosis (SWRO) desalination station of Zeralda (Algiers) is selected as a case study. The assessment criteria for our study comprised net present cost (NPC), cost of energy (COE) and energy balance criteria (EB). Moreover, sensitivity analyses of the global solar radiation, the interest rate, the PV capital multiplier and the PV module efficiency parameter on the optimal hybrid energy system configuration were carried out. The results demonstrate that the hybrid grid-connected PV system has the potential to supply a significant power for seawater desalination station with COE of 0.102 $/kWh. Moreover, the PV production of the optimal hybrid configuration has resulted in 67% of renewable fraction (RF), and an annual reduction of 34.9 tons in the CO2 emissions. [ABSTRACT FROM AUTHOR]

In this study, firstly, the bi-directional energy flow of grid-connected photovoltaic and energy storage system based on power electronic transformer is demonstrated. Based on this, a bi-level programming model is proposed for the location and capacity of energy storage. The optimisation of the location of the outer layer is based on the improved particle swarm algorithm. The energy storage location is a variable, and network loss as well as PET loss are objective functions. The improved particle swarm optimisation algorithm is still adopted to optimise the capacity in the inner layer. The cost of electricity from the main grid is taken as the objective function, and the economic dispatch is realised based on the energy routing strategy of power electronic transformer. [ABSTRACT FROM AUTHOR]

In this study, firstly, the bi-directional energy flow of grid-connected photovoltaic and energy storage system based on power electronic transformer is demonstrated. Based on this, a bi-level programming model is proposed for the location and capacity of energy storage. The optimisation of the location of the outer layer is based on the improved particle swarm algorithm. The energy storage location is a variable, and network loss as well as PET loss are objective functions. The improved particle swarm optimisation algorithm is still adopted to optimise the capacity in the inner layer. The cost of electricity from the main grid is taken as the objective function, and the economic dispatch is realised based on the energy routing strategy of power electronic transformer.

The optimum sizing ratio of the photovoltaic (PV) array capacity, compared to the nominal inverter input capacity, was determined in grid-connected PV (GCPV) systems from two points of view: energetic and economic. The optimum ratio was determined by both empirical and analytical approaches, and based on two PV arrays connected to their inverters, plus three simulated inverters. The flatness of the optimum-energy region due to the inverter characteristics was decreased when economic factors were taken into account. The energetic and economic optimum sizing intervals were defined as the sizing regions causing less than 1% losses from their corresponding optimum points. Subsequently, a compound optimum sizing interval was proposed to maximise the energy injected to the grid and minimise economic costs simultaneously. The results showed that the GCPV system with lower specific DC power generation (kW DC /kWp) and inverter/module cost ratio presented a wider interval (1.12–1.25) than the interval (1.17–1.19) of the system with higher specific DC power generation and cost ratio, for all the analysed inverters. Finally, the optimum sizing ratio was completed by considering a PV module degradation rate of 1%/year, which resulted in a 10% increase in the optimum sizing ratio for a 20-year lifetime. [ABSTRACT FROM AUTHOR]

With the increasing capacity of distributed generation (DG) connected to the power grid, the future generation of photovoltaic (PV) systems are expected to provide a full range of voltage regulation during grid faults in order to enhance the low-voltage ride-through (LVRT) capability of a PV system. In such a condition, the DG should remain connected to the grid for reactive power support, thereby improving voltage profile. This paper aims to propose a control strategy of active and reactive power for a single-stage three-phase grid-connected PV system to enhance the LVRT. The dynamic behaviours of the system were investigated by considering various scenarios such as varying irradiance, local load disconnection, and short circuits, at different locations during the multi-DG operation. Results confirm that the grid-connected PV system is able to remain connected to the power grid during steady-state and transient-state conditions without violating the grid code requirements. The established dynamic behaviour analysis model of the proposed control for grid-connected PV systems can be used in planning an operational strategy for a practical system. [ABSTRACT FROM AUTHOR]

The present paper is an evaluation of two grid-connected photovoltaic (PV) systems, the first combined system installed on the roof of Tetouan's faculty with a rate power of 5.4 kWp, and the second system located in the roof of a commercial building in Tangier with a rate power of 5 kWp. This study demonstrates that the efficiency of the three main PV system technologies: Monocrystalline (mc-Si), polycrystalline silicon (p-Si) and amorphous (a-Si), combined is better than the use of p-Si technology. The study is based on real climate data recorded from January to December 2015. [ABSTRACT FROM AUTHOR]

Application of solar energy in Malaysia has been started in 1998. This country has a large potential of solar energy due to its location at equatorial region. The current energy consumption and demand in Malaysia is describes in this paper. The potential of solar energy in Malaysia is described together with the suitable photovoltaic construction. It also explains the plans conducted by Malaysia involving solar energy that covers investments and also projects involved such as Malaysia Building Integrated Photovoltaic (MBIPV). Simulation of grid-connected photovoltaic system in this study is performed using HOMER software. Finally, the potential of having a grid-connected PV system in a residential area is analyzed. The positive and negative findings in terms of cost and suitability of the system are explained. [ABSTRACT FROM AUTHOR]

Blessed with abundant solar radiation, Malaysia has a huge potential for grid-connected PV (photovoltaic) installations, particularly for its fast-growing residential sector. Nevertheless, Malaysia's PV installation capacity is relatively small compared with the global PV capacity. Significantly, the pricing mechanisms for grid-connected PV projects need to be appropriately assessed to build up the public's confidence to invest in PV projects. In this paper, we analyze the effects of component costs, FiTs (feed-in tariffs), and carbon taxes on grid-connected PV systems in Malaysian residential sector using the HOMER (Hybrid Optimization of Multiple Energy Resources) software. Results demonstrate that the implementation of grid-connected PV systems is highly feasible with PV array costs of $ 1120/kW or lower. For higher PV array costs up to $ 2320/kW, introducing an FiT rate three times higher ($ 0.30/kWh) than the grid tariff for a 100 kW grid sale capacity will, NPC-wise, prioritize grid-connected PV systems over the utility grid. By implementing the FiT ($ 0.50/kWh) and the carbon tax ($ 36/metric ton) schemes simultaneously, grid-connected PV systems will remain as the optimal systems even for costly PV arrays (up to $ 4000/kW). The findings are of paramount importance as far as PV pricing variability is concerned. [ABSTRACT FROM AUTHOR]

This study addresses a static variable load for grid-connected photovoltaic system. In order to make the proposed system more improving powers disturbances, the interconnection of grid- photovoltaic assembled a reversible converter. The power circuit is composed of two 75 watts series photovoltaic panels associates to a static variable load with a dc-dc boost converter interconnect an alternative grid via reversible converter controlled by pulse width-modulation technique. In the dc–dc power conversion, the incremental conductance maximum power point tracking is introduced to improve the conversion efficiency of conventional boost converter. Moreover, a simple control system is designed for the current control of the reversible inverter to synchronize the output current to the alternative voltage in the grid and less variation under static load changes. Obtain results by using Matlab/simulink indicates that the present photovoltaic -grid system able to exchange the direction of active powers in the alternative grid for static variable load caused by reversible converter design. [ABSTRACT FROM AUTHOR]

In recent years the global photovoltaic (PV) market has expanded rapidly due to a sharp decline in PV prices and increased attention to the importance of sustainable energy. Northern Chile has one of the highest irradiance levels in the world as well as one the highest electricity rates in Latin America. Because of these conditions, Chile is one of very few countries where several PV projects are being developed without government subsidies and consequently, the PV industry is experiencing rapid growth. This paper reviews the opportunity to take advantage of these market conditions within the residential sector, modeling PV arrays across 10 cities in Chile. A detailed modeling of PV systems is performed to achieve an accurate analysis of energy production and electricity cost, using local resource data, optimal array orientation and inclination, and production losses. A review of how Net Metering and Net Billing affect the value of the PV production is applied and a comparison using levelized cost of electricity (LCOE) is conducted. Net Metering is found to be a better policy choice to promote PV systems than Net Billing because energy injected into the electrical network is paid at the complete retail rate. However, in developed countries this kind of policy is unlikely to be supported because of it׳s economic unfeasibility. Under a Net Billing scheme a consumer will see an advantage when energy is recorded over longer time intervals and when installing a system with smaller capacity relative to household electricity consumption. This prevents excess generation from being injected into the network which would be bought by the utility at lower prices than the retail rate. Payback periods are found to be low, between 6 years in northern areas with high retail rates and 13 years in other areas with lower radiation and retail rates. [ABSTRACT FROM AUTHOR]

Abstract: In this article, we present the results related to the design, the realization and the experimentation of an autonomous PV system equipped with a solar regulator and digital MPPT command. The solar regulator controls the state of charge of batteries, and in the same time the energy supplied by photovoltaic panels is optimized to the maximum independently of weather. This late function is ensured by a DC/DC converter of Boost-type and a digital MPPT command based on the use of a microcontroller. The results obtained during days with weather perturbations, showed the robustness of the PV system (stability, optimal functioning of PV panels), the good control of charge of batteries under the maximum of energy supplied by the PV panels, according to three phases, determinate the state of charge and the protection against the overcharge and the deep discharge. [Copyright &y& Elsevier]

Abstract: This paper discusses the experimental design of a grid-*connected photovoltaic system based on 16-bit Microprocessor (MCU) SPMC75F2413A. In this paper, the SPMC75F2413A as the main topology control the main circuit of the Single-phase bridge type inverter. The system can track the maximum power point by detecting PV(photovoltaic) voltage, current and grid-connected output voltage and current, and simultaneously can track the frequency and phase by the software phase locked loop. The testing results of the grid-connected photovoltaic system shows that the grid-connected voltage and network voltage are synchronous, and the system is feasible and practical. [ABSTRACT FROM AUTHOR]

Abstract: Traditional electric power systems are designed in large part to utilize large baseload power plants, with limited ability to rapidly ramp output or reduce output below a certain level. The increase in demand variability created by intermittent sources such as photovoltaic (PV) presents new challenges to increase system flexibility. This paper aims to investigate and emphasize the importance of the grid-connected PV system regarding the intermittent nature of renewable generation, and the characterization of PV generation with regard to grid code compliance. The investigation was conducted to critically review the literature on expected potential problems associated with high penetration levels and islanding prevention methods of grid tied PV. According to the survey, PV grid connection inverters have fairly good performance. They have high conversion efficiency and power factor exceeding 90% for wide operating range, while maintaining current harmonics THD less than 5%. Numerous large-scale projects are currently being commissioned, with more planned for the near future. Prices of both PV and balance of system components (BOS) are decreasing which will lead to further increase in use. The technical requirements from the utility power system side need to be satisfied to ensure the safety of the PV installer and the reliability of the utility grid. Identifying the technical requirements for grid interconnection and solving the interconnect problems such as islanding detection, harmonic distortion requirements and electromagnetic interference are therefore very important issues for widespread application of PV systems. The control circuit also provides sufficient control and protection functions like maximum power tracking, inverter current control and power factor control. Reliability, life span and maintenance needs should be certified through the long-term operation of PV system. Further reduction of cost, size and weight is required for more utilization of PV systems. Using PV inverters with a variable power factor at high penetration levels may increase the number of balanced conditions and subsequently increase the probability of islanding. It is strongly recommended that PV inverters should be operated at unity power factor. [Copyright &y& Elsevier]

Abstract: The impact of PV surface orientation and inclination on grid-connected photovoltaic system performance under maritime climates was investigated using validated TRNSYS simulations. Insolation, PV output, PV efficiency, inverter efficiency, system efficiency, performance ratio (PR) and PV savings were estimated annually, seasonally and on monthly bases for various surface inclinations and orientations. Incident insolation and PV output were maximum for a surface with inclination 30° facing due south and minimum for a vertical surface with orientation 90° east or west from south. The monthly optimum collection angle maximising incident insolation varied from 10° to 70°. For the particular location and system studied, the maximum annual PV efficiency, the inverter efficiency, the PR and the system efficiency were for a south-facing surface with an inclination of 20°. For a horizontal surface, the monthly variation of system parameters was significant over a year. For time-dependent tariff rates, the annual PV savings were higher for a system oriented with same orientation towards the west than east from south while for constants tariff rates, the PV savings was the same for east or west orientation from south. [Copyright &y& Elsevier]

In recent years, grid-connected photovoltaic (PV) power generations have become the most extensively used energy resource among other types of renewable energies. Increasing integration of PV sources into the power network and their dynamic performances under fault conditions is an important issue for grid code requirements. In this paper, a PV source as a unified interphase power controller (UIPC) is used to enhance the low voltage ride through (LVRT) and transient stability of a multi-machine power system. The suggested PV-based UIPC consists of two series voltage inverters and a parallel inverter. The UIPC injects the required active and reactive power to prevent voltage drop under grid fault conditions. Accordingly, a dynamic control system is designed based on proportional-integral (PI) controllers for the PV-based UIPC to operate in both normal and fault conditions. Simulations are done using Matlab/Simulink software, and the performance of the PV-based UIPC is compared with the conventional unified power flow controller (UPFC). The results of this study indicate the more favorable impact of the PV-based UIPC on the system compared to UPFC in improving LVRT capabilities and transient stability. [ABSTRACT FROM AUTHOR]

The industrial activities intensification has inevitably caused an excessive use of underground waters and fossils energies, and severe environmental pollution with dire consequences for water resources. This situation intensifies in populated arid regions. In this context, wastewater treatment is a reliable source of water and nutrients for agricultural production. This study aims at treating wastewater using photovoltaic energy, to reduce conventional electricity demand. This paper studies energy and economic feasibility of grid-connected photovoltaic systems (GCPVS) in wastewater treatment plants (WWTPs). The optimization is based on: energy balance, installation surface area and levelized cost of energy (LCOE). Results show GCPVS installed in the northwest of Algeria, can cover 53% of WWTP electrical load and inject 510 MWh/year into grid representing 65% of the load. The regional energy consumption can be reduced by 2% in daytime. LCOE is estimated around 09.14 centUS$/kWh, which is lower than conventional electricity cost 10.17 centUS$/kWh. The benefit-cost ratio is estimated around 0.69 Million US$ (33%). This plant provides 4800 m3/day of agricultural irrigation, where treatment energy cost is decreased from 3.4 centUS$/m3 to 2.3 centUS$/m3. The WWTP fertilize 300 ha of soil per year. This work highlights the efficiency of self-sufficient WWTPs in northern Africa region. • Wastewater treatment plants can serve as dispersed photovoltaic generators. • Use photovoltaic energy to treat wastewater. • Optimal photovoltaic system is proposed for Algerian region wastewater treatment plants. • Eco-energetic analysis and environmental impact of designed photovoltaic system are discussed. [ABSTRACT FROM AUTHOR]