Stand-alone Photovoltaic Power System Research Articles

Mission profile-based assessment of photovoltaic system reliability for Indian climatic zones

ABSTRACT Solar energy is expected to overtake wind energy as the leading renewable energy source by 2050, and therefore, accurate lifetime and reliability predictions for solar photovoltaic (PV) installations are necessary. The microinverter is a pivotal component of stand-alone PV power systems. The reliability of the microinverter depends on the mission profile of the geographical location, such as solar irradiance, ambient temperature, and wind velocity. This study developed a comprehensive reliability map for a 200Wp monocrystalline panel and a 250W microinverter based on mission profile data collected from 198 locations across India. A novel mathematical model is developed and validated using Ansys Icepak to evaluate the junction temperatures of microinverter components. The results show that the junction temperature significantly affects the reliability of PV system. In the hot and dry climatic zone of Jaisalmer, Rajasthan, the maximum MOSFET junction temperature and Mean Time Between Failure (MTBF) obtained were 63.14°C, and 27.34 years, respectively. Furthermore, in the cold and dry climatic zone of Leh, Ladakh, the junction temperature dropped to 29.74°C, increasing MOSFET’s MTBF to 49.8 years. These results prove that the reliability depends on the mission profile, and it should not be ignored in evaluating the reliability of solar PV systems.

Design methodology and implementation of stand-alone solar photovoltaic power system for daily energy consumption of 9.16 kWh

This stand-alone solar photovoltaic power system was designed to power a daily energy consumption of 9.16 kWh reliably, by means of photovoltaic only. The design involves different components whose capacities depend on 9.16 kWh daily energy consumption and 1-day autonomy, including several factors that determine the choice of selection. After implementation, the system was put to the test for two days to ascertain the design validity and check if it would be able to sustain the daily load demand for 24 h without failure. The results reveal that the design methodology employed for the stand-alone system in this study is accurate and reliable because the system was able to power the load interminably for 34 h, with a resulting 0.6% DoD at the end of the test. This was due to the complete energy balance that the design methodology offers. Day 1 shows that the overall PV array power was 208% higher than the daytime load power and 61.2% higher than the overall daily load power. While Day-2 shows the overall PV array power to be 130% higher than the daytime load power and 56.3% higher than the overall daily load power, The energy balance between PV array, battery, and load size was completely and sufficiently achieved on both days, as the highest depth of discharge recorded during the test was 48.7%. The study reveals that through a complete energy balance between PV, battery, and load size, a standalone PV system can reliably sustain daily energy demand. It aims to design a stand-alone PV system capable of reliably sustaining daily energy demand without the need for long days of autonomy, so as to help prevent failures in solar PV projects that come as a result of inappropriate sizing, planning, and a lack of technical know-how.

Design of a Stand-Alone Roof-Top Photovoltaic System for a Residence in Zamfara State, Nigeria

This paper presents in detail the design analysis of a stand-alone photovoltaic power system for a typical residential building in Zamfara State, Nigeria. A photovoltaic power system can be used as a source of electrical power to our homes through the direct conversion of solar irradiance into electricity. The process of harnessing photovoltaic power generating system involves designing, and selection of the different components employed in the system. The success of this process depends on a variety of factors such as geographical location, weather condition, solar irradiance, and load profile. The paper outlines the procedures employed in specifying each component of the stand-alone photovoltaic power system and as a case study, of a medium range energy consumption residence in Zamfara State (Nigeria).

A Novel Horse Racing Algorithm Based MPPT Control for Standalone PV Power Systems

This paper proposes a novel maximum power point tracking (MPPT) method inspired by the horse racing game for standalone photovoltaic (PV) power systems, such that the highest PV power conversion efficiency is obtained. From the horse racing game rules, we develop the horse racing algorithm (HRA) with the qualifying stage and final ranking stage. The MPP can be searched even if there exist multiple local MPPs for the PV power system. Moreover, from the proposed horse racing algorithm, the calculation is reduced, so that the transient searching points are less than traditional methods, i.e., the transient oscillation is less during the MPPT control. Therefore, the HRA based MPPT method avoids local maximum power traps and achieves the MPP quickly even if considering partial shading influence and varying environment for PV panels. Evidence of the accuracy and effectiveness of the proposed HRA method is exhibited by simulation results. These results are also compared with typical particle swarm optimization (PSO) and grey wolf optimization (GWO) methods and shown better convergence time as well as transient oscillation. Within the range from 0.34 to 0.58 s, the proposed method has effectively tracked the global maximum power point, which is from 0.42 to 0.48 s faster than the conventional PSO technique and from 0.36 to 0.74 s faster than the GWO method. Finally, the obtained findings proved the effectiveness and superiority of the proposed HRA technique through experimental results. The fast response in terms of good transient oscillation and global power tracking time of the proposed method are from 0.40 to 1.0 s, while the PSO and GWO methods are from 1.56 to 1.6 s and from 1.9 to 2.2 s, respectively.

Solar Energy Resources and Photovoltaic Power Potential of an Underutilised Region: A Case of Alice, South Africa

Despite South Africa’s international recognition in solar energy investments, the country is struggling to meet its growing energy needs. In recent years, national blackouts and load shedding have been a recurring experience in the country. The high cost of electrification and the overstrained national grid have left several rural communities without access to electricity. This study aims to explore the solar energy resources and performance of a 3.8 kWp stand-alone residential photovoltaic (PV) power system in one of the underutilised regions in South Africa. The study mainly uses ground measured solar radiation data to evaluate the solar resources of Alice and compare them with those in other parts of the world with mega solar PV projects. The components of solar radiation considered are global horizontal irradiance (GHI), direct normal irradiance (DNI), and diffuse horizontal irradiance (DHI). The average total daily GHI, DNI, and DHI of Alice were 4.98, 5.74, and 1.44 kWh/m2. Clear sky conditions were found to occur on 233 days in the monitoring year, resulting in an average total daily GHI of 6.13 kWh/m2, DNI of 6.73 kWh/m2 and DHI of 0.17 kWh/m2. The findings indicated that Alice possesses abundant solar resources for PV and concentrated solar power generation, and is comparable to other regions internationally.

Loss of load probability minimization for stand-alone photovoltaic system using elephant herding optimization

Stand-alone photovoltaic power systems are commonly deployed for rural electrification. Notwithstanding this, non-optimal sizing has been a constant issue in implementing such systems as non-optimal system sizing reduces the system’s reliability in supplying the required power to the loads. Hence, an Elephant Herding Optimization (EHO) is presented for optimal system sizing by searching for the optimal photovoltaic module, solar battery, charge controller and inverter so that the loss of load probability is minimized. Before developing EHO for sizing, an iterative-based approach was formulated to size the system by testing all possible design options. The optimal sizing results obtained from this iterative approach was then used for the validation of optimal sizing solution obtained from EHO-based sizing algorithm. EHO was found to produce same loss of load probability as presented by the iterative approach but with approximately 2.86 times lower in computation time. In addition, it was discovered to be better than evolutionary programming as it had lower loss of load probability with slightly faster computation.

Optimum Parametric Identification of a Stand-Alone Photovoltaic System with Battery Storage and Optimization Controller Using Averaging Approach

The dimensioning of photovoltaic systems is the major concern of researchers and power industry practitioners. This aims to improve energy efficiency and protect the conversion units by a consistent assessment of power conditioning circuits and interconnections for the PV application. In this context, this paper sets out to fulfill detailed modeling and control steps of a standalone photovoltaic (PV) power system with energy storage, according to practical specifications of the load, PV generation unit, and battery pack. The main goal is to estimate all unknown parameters, as the diode ideality factor and revers saturation current, the controller, and the PV link. The PV link interfacing the PV source circuit to the PV-side converter (PVSC) provides a filtering function to maintain a steady voltage at the link. The charge controller used in the PV-side converter is a DC/DC buck converter. It transfers the PV power to the battery and supplies the load. Using pulse- width modulation (PWM) technical, of which the switching duty cycle is the control-input variable; the PVSC power-conditioning circuit is permanently controlled by the maximum power point tracking (MPPT) algorithm to achieve the maximum energy. The battery pack voltage is properly maintained by the charge controller and specified to match the load voltage rating, to avoid a high ratio of voltage conversion. A method is proposed to integrate both the MPPT function and the battery cycle charge. The PV generator output and the power conditioning circuits, mainly constructed from switching- mode power converters, are nonlinear. An averaged model is then derived for dynamic analysis and controller synthesis, using the state-space averaging and linearization method. A PV array of nine PV modules configured into three strings is used in this application to demonstrate the effectiveness of modeling, design, control, and simulation. Simulation model for the controller and power interface is built and developed in short term, using the fundamental blocks of Matlab Simulink.

Feasibility analysis of off-grid hybrid energy system for rural electrification in Northern Ghana

This study examines the feasibility of a stand-alone photovoltaic, diesel generator and battery storage hybrid power system for the electrification of off-grid rural areas in northern Ghana. The HOMER software package was used for simulation analysis. Five optimization scenarios considered feasible by HOMER were evaluated. The evaluation criteria include net present cost (NPC), cost of energy (COE) and emissions. The results indicate that PV/diesel/battery storage hybrid system is the most feasible, optimized, cost-effective and environmentally friendly system among the systems considered. This system has a Cost of Energy (COE) of 0.399 $/kWh and an NPC of $296,552. Although this COE is approximately three times the current energy cost in Ghana, sensitivity analysis shows that changing certain parameters such as fuel costs, and capital subsidies can reduce COE. This shows that if policymakers create the necessary investment environment, such projects can be a viable alternative to rural electrification.

Proposed Method for Two Axis Tracking of PV Modules Using Advanced Microcontroller

In this study, a stand-alone photovoltaic power system was designed and implemented to operate as an application of a digital control system. Sun-tracker is implemented for improved efficiency of the system by keeping the solar module perpendicular to the sun's incoming rays. An experimental system was implemented to demonstrate the effectiveness of the proposed system. Experimental results are given to verify the system's efficiency. A proposed method is employed to seek the maximum power point using two lighting sensors the data obtained from a two sensor is compared by microcontroller. Microcontroller is making PV module track the maximum sun light which leads to obtain a maximum power. The system is implemented using microcontroller and stepper motor and experimental work used to prove feasibility of the proposed method.

Design Aspects of Standalone PV System with Two Simulation Tools

The conventional energy sources depleted day by date. Alternate energy requirement is necessitate for our daily life. Our energy demand is met by standalone PV based system. This paper explained the simulation of a standalone photovoltaic power system erected in Mailam with different simulation tools. Solar resources for the design of this system were taken from the National Aeronautics and Space Administration (NASA) Surface Meteorology at a location of 22° 59' S, 14° 29' E with annual average solar radiation of 5.14 kWh/m2/d. PV planner and PV syst simulation tools were used to analyze the design of photovoltaic power system model. The entire model was designed based on an hour-by-hour data depend on energy availability and its demands. A detailed design of standalone PV system with two different simulation tools were presented in this paper.

A New Hybrid Controller for Standalone Photovoltaic Power System with Unbalanced Loads

Due to several problems such as global concern about environmental pollution, renewable energy has become an alternative source of energy. In situations such as small local loads far from the main grid, standalone hybrid power system (HPS) with inevitable unbalanced loading condition is preferred for the global grid. The four-leg inverter with a simple as well as well-performance control method is a good solution to support this condition. In this paper, with respect to the average and discretized model of the inverter, a new digital controller is proposed in the abc reference frame to control the load voltages. The proposed controller offers several advantages such as simplicity, fast dynamic response, no need for transformation among different reference frames, and full compatibility with digital implementation which makes it as an excellent option to be employed in such systems. In addition, a new hybrid controller is also proposed which not only has the advantages of the proposed digital controller but also shows superior performance under nonlinear loads without imposing a high computational burden. To verify the effectiveness of the two proposed controllers, several simulation and experimental tests under different scenarios on a 3 kW setup are performed.

Design and Control of an Autonomous PV System with Battery Storage and Single Phase Inverter using the Smart Control Followed by PI Correctors

The autonomous photovoltaic system requires a battery for storage of energy, for consumption during the night and days with low irradiation. This article presents the design and control of the autonomous PV system with a storage battery and a single-phase inverter. The SEPIC converter is used to adapt the output voltage of the PV panel to the battery charging voltage, this converter is controlled by the intelligent MPPT control followed by PI controllers to extract the maximum power of the GPV and manage the charge and discharging loop the battery. Subsequently, a BOOST converter has been associated with the system to adapt the output voltage of the battery to the load. The modelling of the state space is done to determine the transfer function of the converters (SEPIC and BOOST). The single-phase inverter is used to supply alternative loads. The values of the PI correctors (Kp and Ki) are obtained using the method of Ziegler Nichols. Finally, we simulated and analysed the performance of a 250W stand-alone photovoltaic power system on MATLAB- Simulink.

A Novel Bidirectional DC–DC Converter with Low Stress and Low Magnitude Ripples for Stand-Alone Photovoltaic Power Systems

Photovoltaic (PV) power is one of the promising solutions to address the fast-growing electricity demand. Electricity generated from the array of solar panels is not fixed due to the continuous change in environmental conditions. Therefore, an efficient power management system is required to facilitate the consumer with an uninterruptable power supply (UPS). When the energy demand is lower than the energy generated by the PV power system, the excessive energy must be stored in batteries and, when the energy demand is higher than the energy generated by the PV system, then the stored energy in the battery must be released in order to fulfil the load demand. Therefore, a bidirectional DC–DC converter is required to store and release energy. Conventional bidirectional converters offer low gain, low power density, low efficiency, high switching stress, and high magnitude of current and voltage ripples. In this paper, a bi-directional DC–DC converter that has low stress and low ripples is proposed for the operation of Stand-alone PV power systems. The proposed converter is implemented in ORCAD/PSPICE (Oregon Computer Aided Design/Personal Computer Simulation Program with Integrated Circuit) and both the charging and discharging modes have been analyzed explicitly. The results were compared with conventional converters and were found to be satisfactory. A significant improvement in the magnitude of output voltage and current ripples has been noticed. Besides, considerable improvement in switching stress (45% reduction as compared with conventional converters) and a 16.6% reduction in the magnitude of ripples was realized.

Stand-alone PV system with MPPT function based on fuzzy logic control for remote building applications

<p align="LEFT"><span>Due to the limitations of reaching the grid utility to remote area, such as rural and/or countryside areas. Stand-alone photovoltaic power systems represent good alternative that it can be adapted for electrical power delivering to these areas. In this paper, a new design of stand-alone solar system suitable for individual building application is presented. This study focuses on proposing a desired solar PV panels matrix arrangement and connection, in addition to presenting an accurate design of Buck-Boost DC-DC converter which controlled by fuzzy logic controller FLC. The controller guarantees the maximum Power Point working conditions and manipulates the fluctuation of the DC link voltage of the matrix due to the weather changing. The main system includes battery bank charger, single phase inverter, and passive power filter. This study addresses the design and performance analysis the DC side of the 7.85 kW PV system. The system performance is evaluated through MATLAB/Simulink results which reflected the promising indications as an effective system for rural individual stand-alone building applications. </span></p>

Battery lifetime enhancement via smart hybrid energy storage plug-in module in standalone photovoltaic power system

Abstract Standalone photovoltaic power system is one of the feasible solutions in rural electrification. However, due to the intermittent nature of solar energy and significant demand variations due to small load size, energy storage devices are needed to ensure power quality and reliability. Lead-acid battery bank has been widely used in such systems to act as the intermediate buffer to compensate the power mismatch between generation and demand, despite the poor lifetime characteristics and relatively short service life compared to other energy storage devices. Most charge controllers only provide basic battery charging functionality and prevent the battery bank from overcharging and deep-discharging. While other notable aging factors such as frequent charge-discharge transition, high C-rate and surge power are often neglected. This paper presents a smart hybrid energy storage plug-in module that aims to enhance the service life of Lead-acid battery in standalone photovoltaic-battery power systems by mitigating life-limiting factors such as current fluctuations and surge current. This module is designed as a plug-in module that can be adopted directly in existing infrastructure in installed standalone PV-battery power system. The effectiveness of the proposed plug-in module in mitigating battery stresses is simulated in Matlab Simulink with actual solar irradiance data and estimated load profile for a rural community in Sarawak Malaysia. The simulation results are validated experimentally with the scaled-down photovoltaic-battery power system. The effectiveness in mitigating battery stress is quantitatively evaluated with battery health cost function, while the reduction in overall battery cost is analyzed and discussed.

Design of Neuro-Fuzzy Controller for Stabilization of Single Phase Stand-Alone PV Power System

For the three phase power electronic and drive applications, vector control or the synchronous reference frame (SRF) based control concept is well accepted and settled amongst the research communities. Although the SRF concept has gained popularity and appreciation in developing the three phase controllers, still the concept has not reached the same level in case of a single phase system. The work presented in this paper is mainly concerned to the design of a hybrid Artificial Neural Network and Fuzzy Logic based controller for a single phase stand-alone photo-voltaic (PV) power system. The adaptive neuro fuzzy inference system (ANFIS) controller proposed in this paper is chiefly meant for improving the transient and steady state responses; for minimizing the distorting effect of the low order load current harmonics encountered particularly in case of switching the drive based inductive loads and to help maintain the inverter output voltage constant under different loading circumstances. The result obtained through simulation work, shows the effectiveness of the proposed controller as compared with the previously established research works.

Self-sufficiency of 3-D printers: utilizing stand-alone solar photovoltaic power systems

A self-replicating rapid prototyper (RepRap) is a type of 3-D printer capable of printing many of its own components in addition to a wide assortment of products from high-value scientific or medical tools to household products and toys. There is some evidence that these printers could provide low-cost distributed manufacturing in underprivileged rural areas. For the most isolated communities without access to the electric grid, a low-cost alternative energy is needed. Solar energy can be harvested through a stand-alone photovoltaic (PV) power system specifically designed to match the needs of the RepRap. The voltage and current requirement for the printer demands the use of buck along with a bidirectional DC converters to ensure proper operation. This paper provides the design for a stand-alone PV—lithium ion battery power system with an efficient controller. Robust and agile PI controller schemes are utilized to efficiently maintain the distribution of energy through the power system. The system was defined with ordinary differential equations, simulated and tested for two operational conditions in MATLAB/Simulink. The results showed that the controller developed operates the system in a stable condition and the simulation shows steady acceptable behavior that makes this system highly suitable for hardware implementation.

A comprehensive study of battery-supercapacitor hybrid energy storage system for standalone PV power system in rural electrification

The standalone photovoltaic power system is one of the promising solutions in rural electrification which has been widely implemented to supply electricity for basic household needs. Standalone photovoltaic power systems normally integrate energy storage devices, mainly Lead-acid battery, to compensate the supply–demand mismatch due to the nature of solar energy. However, the short cycle life of Lead-acid battery increases the operating cost of photovoltaic power systems. Supercapacitor-battery hybrid energy storage system has been proposed by researchers to extend the cycle life of battery bank by mitigating the charge–discharge stress due to the fluctuating power exchange. The existing hybrid energy storage systems and their corresponding energy management strategies vary in terms of topology, complexity and control algorithm which are often application oriented. This paper presents a comprehensive review of the state of the art for HESS and discusses potential topologies that are suitable for improving the service life of Lead-acid battery in standalone photovoltaic power systems. Theoretical analysis and numerical simulation in Matlab Simulink for different hybrid energy storage system topologies in rural residential energy system applications have been carried out and their effectiveness in mitigating battery stress are investigated and compared. A battery health cost function is proposed in this paper to quantify the impact of many damaging factors on battery, thus the effectiveness of different hybrid energy storage systems in mitigating battery stress and the associated financial analysis can be quantitatively compared. Finally, a scaled-down hybrid energy storage system prototype has been developed and its performances in standalone photovoltaic system are emulated to validate the simulation analysis.

The Efficiency Improvement of the Stand-alone Photovoltaic Power Systems

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A Practical performance verification of AFLC based MPPT for standalone PV power system under varying weather condi-tion

For amelioration of tracking efficiency, the Maximum power point trackers (MPPT) are very important for photovoltaic (PV) generation. For this purpose here a reformed adaptive fuzzy logic control (FLC) MPPT tracker has been presented to enhance its overall power efficiency and gives rapid transient response under changing weather conditions. For voltage regulation at load bus, the zeta buck-boost converter has been taken for its least voltage ripple. MATLAB/SIMULINK simulation environment and dSPACE DS1104 real time control board is used to test the proposed adaptive fuzzy logic controller based MPPT in variable irradiance level and ambient tempera-ture. The tracking efficiency in this presented method is analyzed in comparison with standard fuzzy logic controller (FLC) and perturb and observe (P and O) MPPT algorithms. The modified AFLC controller gives better tracking efficiency and precise response compared to conventional fuzzy logic controller and P and O MPPT algorithms. Theoretical and experimental results obtained are demonstrated for improved functioning of the system.