# Simulation Model of PV System Function in Stand-Alone Mode for Grid Blackout Area

Authors: Bibhu Prasad Ganthia; R. Dharmaprakash; Tushar Choudhary; T. Vijay Muni; Essam A. Al-Ammar; A. H. Seikh; M. H. Siddique; Abdi Diriba
Journal: International Journal of Photoenergy
 (2022)

---

## Abstract

PV systems are frequently used in a stand-alone configuration. In a solar PV-based energy-producing system, power fluctuation is a natural occurrence. Alternative sources of energy, including such hybrid grid-tied or energy storage systems, could be discovered when solar PV systems run off-grid to satisfy regional power demands for reliable power supply. This research uses an unusual PV system that can function in both grid-connected and stand-alone states to propose an efficient approach for the power generation challenge in the residential segment. A block of storage battery with sufficient dimensions is included in the system to make sure the constant power supply of such a residential building with an average electricity demand of 10 kWh. An atypical 3.2 kWp PV system and a 19.2 kWh storage battery brick was determined to be capable of meeting the house’s whole daily energy requirements, as well as the defined electrical shutdown times, to simulate the system, which took into account the day load profile, network cutoff times, and monthly radiation from the sun. The collected simulation results showed that during 9 months of each year, the generated PV energy surpasses the load needs, resulting in a maximum battery state-of-charge (SOC) in the range of 74-85%. The generated PV energy is an approximately proportional requirement as during 3 months of minimum solar irradiance (Dec-Feb), whereas the sequence’s SOC differs between40 and 49%, demonstrating the validity of the proposed photovoltaic system. In January and July, the PV service’s daily energy produced ranges between 2.6 and 5.4 kWh/kWp, corresponding to a conversion efficiency of 90% and 66.25%, correspondingly.


---

## Body

## 1. Introduction

Microgrids are low-voltage networks that include combination of distributed (DG) units, energy storage systems (ESS), and load, controlled demand that can operate either as stand-alone modes [1]. In a state, the microgrid modifies power leveling in free enterprise activities by getting power from the main system or providing electricity to the grid to improve operational benefits. The microgrid is separated from upstream distribution systems in stand-alone operation, to maintain a constant power supply to the customers who use DG. Different types of methods are used as elements of the microgrid to minimize the power swings of nondispatchable DG units, such power dynamic of every distributed energy generating unit, charge and discharging of ESS, and load variations.A network-controlled dependent voltage-sourced converter (VSC) or a networking framing agrees to take two modulation techniques utilized in a microgrid. To achieve stable and cost-effective functioning, a microgrid normally requires a powerful platform to enable dynamic referencing power factor, ensuring collaboration among the controlled components. With the quick rise in fossil fuel prices, and also the sharp rise in the construction price of building normalized pattern facilities, there is a renewed focus on alternative generating systems that use energy more efficiently [2]. The electricity sector gets increasingly competitive as a result of activities and reorganization of power networks. Solar, freshwater, air, geological, and wastes generated are the most common alternative energy sources. Solar energy is widely available and may be used in practically anyplace. Many countries have taken major steps in the new millennium to tap into the vast and environmentally benign solar energy supplies. These countries invest much in both development and public awareness campaigns aimed at environmental protection. High-quality studies will lower manufacturing costs while also improving the efficiency of allied solar energy-harvesting equipment [3]. Furthermore, public understanding will raise the demand for these devices in the industry. As a result, the technology will be given out at a cost-effective rate.Renewable energy systems (RES) present a cleaner solution capable of fulfilling the growing electrical requirements of linked and remote communities. Microgrids (MGs) have piqued the scientific group’s interest in recent years, as well as being a possible alternative for future conventional power generation. MGs are being considered as a potential solution for integrating intermittent renewable energy supplies into traditional grids [4]. Many implementations have been applied in SG, notably in the construction of controller and electronic band converters, as a result of the advent of new communications technology such as microprocesses devices and developments in power electronics. Experts had made major contributions that can have a substantial influence in such domains in recent years, particularly in the context of data collecting, mechanization, and management of MGs. MGs not just reliably and cleanly connect electricity renewable to the main grid, as well as provide greater validity in its design to function within the face of natural disasters and interconnected power grids, resulting in lower energy failures in distribution and transmission, as well as reduced building and financial moment.Connecting terminals with defined and estimated capacities are used to transmit and supply electricity generation. Electrical supply increases in some circumstances, forcing distribution networks to plan electricity supply over multiple periods ranging from 6 to 10 hours each day [5]. Communities and other industries face a serious problem as a result of this situation. This problem has existed for more than ten years, and there are no signs that it will be resolved in the coming years given the political scenario remaining constant [6]. Mounting PV systems on private residences and other privately or publicly facilities with pretty modest minimum fuel use, on either hand, is a viable solution for a wide spectrum of such users, who account for a significant portion of Gaza’s overall consumption of electricity. Throughout grid outages, the PV power systems should provide a constant supply of energy, and during the day, this can feed extra produced electricity into the electricity network.Due to such island operation of the converter, which is a necessary significant aspect with each grid-connected converter to fulfill the safety requirements, grid-connected PV systems may continue to deliver electricity generation during grid shutdown hours [7]. As a result, if the PV system does not have energy storage, the electricity generation produced by the PV system throughout blackout periods would be lost. This results in significant energy waste and lengthens the time it takes for photovoltaic systems to repay for themselves. Stand-alone PV systems are two types of photovoltaic (PV) systems that utilize solar fuel to power electricity. The stand-alone PV system is represented in Figure 1. The grid kind is linked directly to the power grid and operates in comparison only with resource load demand [8]. There is also no requirement for battery storage in this PV system because it does not allow for autonomy. Its size ranges from a small-scale distributed roofing system with a few kW to a large central grid-connected system with an MW capacity, and it uses an inverter to translate DC electricity produced by aPV arrays back AC power that can be delivered into the grid. On either side, a stand-alone or off-grid photovoltaic system does not connect to the power system.Figure 1
Stand-alone photovoltaic system.This kind of PV system includes a PV system for producing power, energy storage equipment including such battery, energy ventilation system, or AC or DC electrical demands. A grid-connected PV system reduces electricity and capability inefficiencies in the distribution systems, as well as delays or prevents distribution and transmission systems upgrades [9]. Consumer demands are also unconstrained because energy is delivered to the electric grid. The grid integration service’s functioning, on the other side, is contingent on the occurrence of the power scheme. Stand-alone photovoltaic systems, on either side, have found use in rural places where the grid connection is limited. For instance, rural electricity, telecommunications, and pumping systems are all examples. They demand more upkeep but also give you a great sense of freedom.The goal of the research is to recommend the solution to these problems by providing a different PV system that includes storage batteries, charging controller, grid-attached, AC/DC bilateral change, and process regulator. That means savings can be saved by the battery. This can prevent excessive energy without wasting. It also helps monitor and categorize the submissions charging through the circuit [10]. The technology was developed to accommodate the advantage of all available network hours, not just for providing the demand but also for recharging batteries. On either side, it will use all of the PV-generated electricity to charge batteries, provide the load, and feed the extra electricity back into the grid. In comparison to another traditional photovoltaic system, the proposed solar system is unique in that it can function in both stand-alone states without compromising the islanding security features. On either side, unlike traditional grid-connected photovoltaic system, which typically functions at a voltage source of 400–600 V, the suggested system operates at a drastically reduced voltage source of 48 V, which is safer and allows the required number lithium batteries to be reduced with only 24 cells [11]. The simulation outcomes of this research verify the correctness of the advanced software architecture and demonstrate that its manufactured and preserved electricity generation is fully sufficient to cover overall load requirements throughout the year, indicating that the advanced system design is a viable solution to address the grid outage issue for a huge proportion of a residential market. However, leading to a shortage of papers upon an unusual PV system that is created for a specific scenario, the received testing data could not have been matched to other analogous findings.


## 2. Related Work

This paper offers a grid-tied photovoltaic (PV) control adaptation topology with a new grid resynchronization mechanism. The goal of this plan is to provide continuous energy to the system while also nourishing control to the network. The control strategy aids in a harmonic compensation and energy quality improvement while obtaining the most generated by the PV array. The suggested arrangement is managed to utilize three ways, characterized as the grid control scheme, points of conventional connection (PCC) voltage regulation, and purposeful transient stability with resynchronization, dependent on the amount of grid energy. Within these modes, a basic error signal controller controls grid frequency, voltage output, batteries, and the direct current (DC) connection amplitude. A control strategy is also presented for rapid and horizontal evolutions between modes. The system’s durability in the face of irregular solar irradiance, linear model, and grid supplies interruptions makes it a good fit for a home application. The findings of the controls, architecture, and simulations are given to illustrate that the suggested system operates satisfactorily [12].Photovoltaic (PV), that could be independent, off-grid linked, or a grid-connected, is viewed as among the most promising alternatives for underdeveloped countries like Rwanda to minimize difficulties associated with energy shortages. Despite developments in renewable technology, Rwanda’s present electricity rate is projected to be 59.7%, and hydroelectric maintains the country’s principal source of energy. Rwanda’s administration has vowed to attain 48 percent of its overall electricity targets through off-grid photovoltaic panels by 2024 to supply inexpensive energy to low-income homes. By constructing an easy and low off-grid photovoltaic system, a comparison of results among a single household as well as a microgrid photovoltaic is undertaken. For a private household, the battery model is 1.6 kWh everyday demand with 0.30 kW peak demand, while for the off PV network, the storage model is 193.05 kWh/day and 20.64 kW peak load. For each of these energy generation representations, the hybrid optimization model for electric renewable (HOMER) software is utilized that estimate a network size or life cycles cost, which includes the net present cost (NPC) and levelized cost of energy (LCOE). The optimal program’s LCOE, NPC, electricity generation, and operational cost are predicted to be 1,166,898.0 USD, 1.28 (USD/kWh), 221, and 715.0 USD for the grid and 9284.4 USD, 1.23 (USD/kWh), and 2426.0 USD for an only one stand-alone, correspondingly, according to the analysis. When evaluated to a regional PV network that provides power to a remote county in Rwanda, the LCOE of such a stand-alone PV scheme for individual residence is shown to be charge-effective [13].Stand-alone mode offers the highest effectiveness of the control of a matrix converter, stand-alone PV converter. Initially, a DC-DC boost converter with quadratic back-stepping regulator was modeled and designed. The suggested converter extracts the maximum power point (MPP) by the properly reacting to variable atmospheric circumstances by using a standard voltage supplied by the perturb and observe (P&O) technique. One purpose of the boost converter is to increase the voltage at the inverter’s intake while needing a transformer; proposed system is less small and less costly. Next, the single-phase on H-bridge converter was regulated with back-stepping control to minimize the error among the inverter’s voltage level and the target variable; however, there was a significant load variation at the inverter’s production. Lyapunov’s stable concept was used to verify the boost conversion and H-bridge inverter’s reliability. The suggested photovoltaic system using back-stepping controls has a strong recovery of the MPP, with effectiveness of 99.83% and a speed of response of 1 ms, according to simulation findings. Furthermore, the inverter’s voltage output is regulated to 220 V in its sine format, and the overall harmonic component of the output power is little more than 1% [14].The rapid development in the production of renewable power generation to the power process is due to the use of conventional energy sources and environmental concerns. The reduction of power loss and voltage profile might be significant advantages of distributed energy resources (DG). Nevertheless, studies reveal that inappropriate ESS design and size result in unintended energy losses and risk of voltage stability, particularly in areas where renewable power adoption is strong. To address the issue, this study establishes a microgrid created on IEEE 34-bus distribution network that includes wind power, photovoltaic system, and production of diesel, including energy storage systems about particular types of loads. Furthermore, the research proposes the particle swarm optimization (PSO) technique for minimizing power loss and improving system output voltages by efficiently managing various types of renewable power under the worst-case scenario of renewable power. Case educations were approved out using the well-established IEEE 34-bus system. The thorough simulation results for each example highlight the importance of optimal configuration organizational structure as well as the efficacy of the proposed approach [15].A single-phase freestanding PV device with two steps of converters is shown in this research. The goal of this project is to track the MPPT so that the extreme possible control can be transferred to the load, as well as to manage the production of current so that the AC load may be fed with a sinusoidal waveform. These objectives are met by designing control rules for the boost DC-DC and an inverter switch utilizing the slipping mode. As a result, a sliding mode MPPT and outputs control technique are presented. The work’s unique feature is that it proposes a freestanding PV system using controls based exclusively on adaptive control. Under quick fluctuations of irradiance level, the suggested system is designed and analyzed in MATLAB/Simulink environment. The findings obtained with the proposed MPPT are instead compared with the results with the incremental conductance (IC) approach. These findings show that the sliding manner (SM) MPPT outperforms the fixed mode MPPT in terms of timing velocity, effectiveness, and responsiveness. Furthermore, the current controller produces a high-quality control signal with a THD of 3.47%. Moreover, these controls are assessed under the changes of two daily meteorological patterns and contrasted to the IC approach for valid results. The findings show that the trajectory tracking MPPT can generate more electric power than an IC MPPT, with advantages of up to 13.12% for the bright daily pattern and 27.67% for a gloomy day pattern [16].


## 3. Materials and Methods

### 3.1. Characteristics of PV Cell

The majority of solar panel is made up of a series of modules. A p-n connection, which creates small amounts of electricity to the reflected light, can be used to depict this organism. Various analogous circuit designs are provided to investigate the electrical characteristics of the PV cell [17], because of its strong performance concerning substantial fluctuations in temperature and irradiance. The most commonly used designs for PV cell modeling is shown in Figure 2.Figure 2
PV cell single diode model.A photocatalytic generation sourceIph in parallel connection, the connected in series Rs, and also the shunt resistance Rsh make up the circuit diagram in Figure 2. The output current Ipv is calculated by expression (1) using Kirchhoff’s rules:
(1)Ipv=Iph−IosexpAVPV+IPVRs−1−VPV+RsIpvRsh,where A=q/γkTTNcell.The differences in light-generated currentIph are dependent on the observed and referenced irradiance level parameters as chosen to follow
(2)Iph=ISC+KiT−Trefλλref.The current is flowing in the diodeID described by the Shockley equations, as shown in formula (3), where Iosindicates the saturation current and is represented by
(3)Ios=IorTTref3expqEGkγ1T−1Tref.The utilization of series/parallel modules in PV energy systems is dependent on the amount of power required and the voltages employed. The main goal of PV cell mathematical analysis is to obtain precise outputs of current or voltage results for the study to display the I-V and P-V features [18]. In Figure 3, the latter is depicted. The voltages and currents are affected by irradiance and temperature, correspondingly. In addition, the maximum output changes with irradiation and temperature.Figure 3
Photovoltaic backup system.


### 3.2. Proposed Method of PV System

The suggested PV scheme can be used in either grid-connected or stand-alone configurations. Figure3 displays a structure of a system. The photovoltaic panel, cell battery, power converter devices, and control method are the essential components.


### 3.3. Photovoltaic Generator

PV modules are connected to the circuit, based on the power and voltage of the DC supply [19]. Monocrystalline or crystalline silicon photovoltaic modules were chosen because of their excellent quality and reduced depreciation over long durations when compared to other PV systems. The photovoltaic module is helpful to improve the quality of the generator. In it, the PV module was connected to the control bus. This control bus carried the control signals from the PV module to the inverter. This module was connected to the battery. The inverter circuit connects with the AC power supply. Then, the input current quality was enhanced by the PV module.


### 3.4. Cell Battery Storage

Due to repeated grid shortages, the battery unit includes static cells which can withstand a deep depletion, having a maxima cycle frequency surpassing 1000 times [20]. These lithium batteries offer high amp hour effectiveness of 80-90 percent as well as a high life expectancy of more than ten years. The ability of a battery is the size of the electricity stored within it, and it depends on the size of it. And it is determined by its lifetime depending on the nature of the term. The changes that are stored here are determined by its various standards.


### 3.5. Regulator of the Battery Charge

It is utilized to keep the battery building’s charging rate under control and safeguard it from overcharging and excessive overcharging. The value sensor is used to calculate the voltage levels and open or close switch S2 and per the battery’s state-of-charge, as indicated in Figure3.


### 3.6. Inverter 1 and Inverter 2

It is a grid-connected converter that converts PV generator DC source electricity to AC electricity exported to the grid. It features MPPT control techniques, management to kind the converter grid-connected, an anti-islanding technique to guarantee protection when a cutoff grid moments [21]. The bidirectional energy conversion can work as a converter to transfer DC to AC and also a radiator to transfer AC to DC electricity. In grid outages, it would deliver AC power to the demand as from battery blocks in the first mode. It functions as a converter in the second scenario; charge the battery component first from the grid throughout its levels of attention [22]. This converter is not intended to provide AC baseload power as from a battery bank. In the event of a grid shutdown, the reference signal Ig is primarily utilized to remove inverter 2.


### 3.7. Power Meter

This pattern is utilized to track how much energy is dissipated from a grid when serving the demand or charge the storage wedge, as well as how much electricity is exported to the grid from aPV scheme. This pattern was connected following the electricity law known as network monitoring.


### 3.8. PV System Design

The process measures will be considered while evaluating the planned PV system elements depicted in Figure3:
(i)
The daily global solar electricity production on flat surfaces is 5.4 kWh/m2 day, corresponding to the average maximum sunlight hours PSH=5.4h/day(ii)
In the city, the everyday consumption of electricity of a residential real estate and one publicly or privately utility is 10 kWh/day; this amount of energy indicates the consumption of a significant number of existing households and modest publicly or privately institutions daily [23]. Furthermore, the required installation surface of the equivalent PV generator is around 25 m2, allowing for easy deployment on a building roofing(iii)
To choose the right order for a particular voltage for our method, its publishing electronics should be given more than voltage. If so, it will use the stream lord. This may cause the risk of wasting power(iv)
The efficiency (ɳinv) of inverter 1 and inverter 2 is 94%, whereas the charging agency’s CR is 96%(v)
A block current battery maximum current effectiveness isɳBAh=85%(vi)
The DC system power is calculated at 48 V to keep the battery’s block voltage from exceeding a harmful level. The rate of heat transfer between two surfaces is equal to the temperature difference divided by the total thermal resistance between two surfacesTables1 and 2 show the detailed simulated findings for this position in terms of annual power output and consumption, as well as the quantity of yearly converters inefficiencies.Table 1
Yearly power production and consumption on a stand-alone system.
ConstructionkWh/yearPercentage (%)ConsumptionkWh/yearPercentage (%)Photovoltaic system1564100%AC primary demand432100%Overall1564100%Overall432100%Table 2
Yearly losses in electrical power in a stand-alone system.
MeasureConverterRectifierComponent unitsOperation hours64530hrs/yearPower in4630kWh/yearPower out4370kWh/yearLoss430kWh/year


### 3.9. Sizing of PV Generator

The highest power of aPV array generatorPPV is represented in
(4)PPV=EdPSH×ɳinv×ɳCR,while Ed seems to be the private house’s average power consumption (kWh/day), PSH seems to be the peak solar hours (hours per day), ɳCR represents charging controller effectiveness, and ɳinv is converter effectiveness.This can calculate the peak produced by the PV system in Watt peak (Wp) using the above model parameters represented in(5)PPV=100005.4×0.93×0.95=2096Wp.To ensure constant power is available throughout grid interruption hours and to account for cloudy weather as well as all voltage regulation losses, a PV generating with such a maximum output of 3200 Wp will be chosen [24]. Furthermore, boosting the PV peak output will ensure that the battery block maintains an acceptable state of charge. The PV module will be a polycrystalline module with 72 compartments that are related with such a peak output of 320 Wp. In this example, the PV generator will be made up of five series connections; that is, each is made up of two PV modules linked in series and has standard DC energy of 47 V, as illustrated in Figure 4 [25]. This energy is chosen to suit a battery storage block’s voltage level.Figure 4
PV generator.


### 3.10. Storage of Block Battery Design

When mounting the battery block in such an uptown building, the standard cell block power is calculated to be 48 V, which would be acceptable [26]. The storage space of the battery’s blocks would be chosen to fulfill the energy load requirements for a couple of days even without sunlight or the electricity supply. CBAh (total ampere hour) is calculated as follows:
(6)CBAh=Edb×ASDOD×VB×ɳBAh,where Edb is the everyday energy demand from the batteries (Ed/inv), DOD is a allowable penetration of discharge, AS is autonomy times, ɳBAh seems to be the batteries cell’s ampere hourly effectiveness, and VB seems to be the battery block’s chosen minimum DC voltage. The ampere hour load is calculated using actual values for various variables, such as AS=2.25days, DOD=0.8, and ɳBAh=0.85 and also VB=48V.
(7)CAh=1000/0.93×2.250.8×48×0.85=741.2Ah.A lead-acid battery block bank classified at800Ah/2V would remain chosen to a construct the loading solution that comprises 24 cells that are associated to offer a DC power supply of 48V/800Ah, to improve the battery energy storage stress distribution and to reverence, industry manufactured norm standards. This battery block has a battery performance of Cwh=19.2kWh, which would be suitable for interior placement in a household residence.


### 3.11. Regulator Charge Selection

The charge regulators would be evaluated at an input power in the region of 44-86 V and a voltage level of 3.2 kW, whereas its minimum voltage output is 48 V, taking into account the PV battery’s amount of voltage and maximum output.


### 3.12. Inverter Selection

Inverter 1 is still a 4 kVA only one DC/AC inverter that runs at a steady-state operation and has a dynamic performance of 220 V and 50 Hz, respectively [27]. As indicated in Figure 3, it provides the power supply via switch S1 and the power infrastructure with electricity generated by the PV generation via a bidirectional kWh-meter. This convertor is controlled by a system and developed to lock down in the event of a grid outage, ensuring total security.


### 3.13. Bidirectional Inverter Selection

It is a 5 kVA bidirectional inverter that was chosen to provide AC power from the storage block to demand while also generating electricity from a network when a PV power is restricted for the lengthy time, such as during wintertime.During conduction, heat is transferred through the vibration of molecules in a substance. As something gets warmer, it begins to increase the vibration and movement of the molecules that it consists of. In solids, particles are closely packed together and are in direct contact.


### 3.14. System Modes

The solar level of radiation, network disruption periods, the battery’s SOC, and autility grid are all variables that will cause the system to function in various modes [28]. Under some of these circumstances, the mechanism in Figure 3 will select the appropriate configuration from Table 3.Table 3
System operating modes.
ConfigurationSwitch 1Switch 2Description100Power cutoff, PV generation storing the batteries, and the cell blocks supplying electricity to the demand.210Grid connectivity is accessible, and load is drawn straight from the network.301The battery’s SOC is minimal, and a cellblock is supplied by both the PV system and the network at the same moment.411Grid connectivity, battery charge from the PV system, and surplus generated energy pumped into a network to supply the required. This state is not appropriate for this technology.


### 3.15. System Evaluation

The system simulations have been carried out using the given system design. Whenever the network is unavailable, the PV scheme and the stored power in the storage blocks were being utilized to fulfill a capacity demands [29]. During network available hours, its electricity would be used to meet power demands and fill the battery blocks, based on its charging condition. The simulation tool examines the energy requirements and PV energy output at every hour cycle and then decides whether to charge or discharge the batteries or infuse additional energy into the network regarding the difference.


### 3.16. Everyday Demand Curve

The load demand profile displays the load variance that is dependent on customer behavior. The main demands in a typical residential dwelling are lighting, television, computers, and household appliances including fridges, freezers, and dishwashers. As per Black’s Law Dictionary, “Residential dwelling means living in a certain place permanently or for a considerable length of time” as per Merriam Webster dictionary.In the computer simulation, the load profile indicated in Figure5 is taken into account [30]. The produced annually of PV energy system, the battery SOC, and the thermodynamic efficiency have all been evaluated using computer simulation depending here on everyday load profile illustrated in Figure 5.Figure 5
Typical everyday demand curve of a residential.


### 3.17. System Component Modeling

The objective of system modeling is to test the state’s performance under various settings and seasons. It is carried out utilizing PV array, battery, charge controller, and inverter numerical simulations [31]. Hourly meteorological data, temperature, and humidity and a load demand curve are used as input data. The calculation results give a quick summary of the mathematical methods.


### 3.18. Estimation of PV Power Output

PV maximum output at standard trial condition (STC), solar irradiance, and module temperatures are all important components in generating DC electricity from a photovoltaic system. This is an example of a simple design.(8)PPVout=PPVPeak×SSref×1+KTTc−Tref.From equation (8), where PPVout seems to be the PV array’s power factor, PPVPeak seems to be the PV element’s power at STC, Sseems to be solar energy in W/m2, Sref is represented as solar energy at STC of 1000W/m2, KT seems to be the thermal diffusivity of mono- and polycrystalline Si cells, KT=371031/°C,Tref is the source temperature at STC of 25°C, and Tc represents temperature coefficient estimated using a next econometric model.
(9)Tc=Tamb+0.0256×S,where Tamb represents the ambient temperature in equation (9).


### 3.19. Battery Storage Block

In the event of a grid failure or if the operation is performed in a stand-alone operation, a battery is created to gather the extra power generated by PV. They also continue to improve the demand whenever the PV power is insufficient to generate electricity. The following equations are being used to express the efficiency of charging and draining the battery blocks [32]. The rechargeable battery block has two modes of operation: charge and discharge. During charge controller in equation (10), the PV energy increased by the control authority’s effectiveness above the bidirectional inverter’s input signal inv2, which represents the power demand divided by inverter 2’s effectiveness. This power Pcharge would be increased by the battery’s charge effectiveness and then increased by one 60 minutes to contribute to the current battery charge (equation (11)). Since the simulation duration is one hour, the multiplying is by 60 minutes.The batteries will discharge powerPdischarge as during discharge mode (equation (12)) to compensate the deficit that occurs when the demand that exceeds a PV power. At cathode or positive electrode, due to oxidation, nickel hydroxide becomes, nickel ox hydroxide releasing water in the electrolyte solution. During charging of battery, the secondary battery turns to its original charged state and is ready for further discharging of battery. The energy released from the batteries is calculated by multiplying the PV power by a charging regulation performance, subtracting the power demand split by the bidirectional inverters effectiveness (inv2), and then dividing everything by the rapid charging effectiveness, as shown in (12). The discharge energy would be increased every 60 minutes, and the energy of a battery’s blocks would be deducted:
(i)
Charging operation(10)Pcharge=PPVO×ɳCR−PLɳinv×ɳBAh,(11)EBt=EBt−1+Pcharge×60minutes(ii)
Discharging operation(12)Pdischarge=PL/ɳinv−PPVO×ɳCRɳBAh,(13)EBt=EBt−1+Pdischarge×60minutes,where EB is the current battery energy generated (Wh), PPVO is the PV element’s power output (W), PL is a needed load energy (w), Pcharge is represented as voltage stimulating to a battery when charge controller (W), and Pdischarge is the energy discharge from batteries while discharging state (W). The rate of heat transfer to an object is equal to the thermal conductivity of the material the object is made from, multiplied by the surface area in contact, multiplied by the difference in temperature between the two objects, and divided by the thickness of the material.


### 3.20. Simulation Algorithm

The numerical methods presented above in this paper make up the system model. Figure6 depicts the experimental flow diagram. The application determines the MPP dimensions Imppf,Vmppf power output produced by the solar generator, or available energy during day and night utilizing weather information (solar insolation and temperatures), modules supplier information, and the condition of the electricity systems. This has used the MPP parameters Imppf,Vmppf at STC and the NOCT circumstances supplied by the company to assess the simulation program.
(i)
The PV scheme generates enough energy to meet the needs of the household. PV energy will take precedence over draining the battery and using the network if this is capable to satisfy load requirements [33]. If there is extra PV power, it will be pumped into the network or used to charge and discharge block under its state of charge(ii)
The PV power generated is insufficient to meet the load. If grid electricity is supplied, utilize it first; if grid services are not available, empty the maximum load of electricity from storage blocks(iii)
The amount of PV electricity produced is insufficient to meet the demand requirement, and the battery’s SOC is low. The grid can then be used to simultaneously charge and discharge blocks and fulfill the capacity demands(iv)
Grid stoppage intervals are, in reality, unpredictable in time and dependent on the state of the energy grid and cannot be determined by the PV user [34]. As a result, the model treats the PV scheme as a stand-alone system, and that is the worst-condition scenario. As a result, a software database depending on the flow chart is shown in Figure 6 is created to assess the network efficiencyFigure 6
Flow diagram.


## 3.1. Characteristics of PV Cell

The majority of solar panel is made up of a series of modules. A p-n connection, which creates small amounts of electricity to the reflected light, can be used to depict this organism. Various analogous circuit designs are provided to investigate the electrical characteristics of the PV cell [17], because of its strong performance concerning substantial fluctuations in temperature and irradiance. The most commonly used designs for PV cell modeling is shown in Figure 2.Figure 2
PV cell single diode model.A photocatalytic generation sourceIph in parallel connection, the connected in series Rs, and also the shunt resistance Rsh make up the circuit diagram in Figure 2. The output current Ipv is calculated by expression (1) using Kirchhoff’s rules:
(1)Ipv=Iph−IosexpAVPV+IPVRs−1−VPV+RsIpvRsh,where A=q/γkTTNcell.The differences in light-generated currentIph are dependent on the observed and referenced irradiance level parameters as chosen to follow
(2)Iph=ISC+KiT−Trefλλref.The current is flowing in the diodeID described by the Shockley equations, as shown in formula (3), where Iosindicates the saturation current and is represented by
(3)Ios=IorTTref3expqEGkγ1T−1Tref.The utilization of series/parallel modules in PV energy systems is dependent on the amount of power required and the voltages employed. The main goal of PV cell mathematical analysis is to obtain precise outputs of current or voltage results for the study to display the I-V and P-V features [18]. In Figure 3, the latter is depicted. The voltages and currents are affected by irradiance and temperature, correspondingly. In addition, the maximum output changes with irradiation and temperature.Figure 3
Photovoltaic backup system.


## 3.2. Proposed Method of PV System

The suggested PV scheme can be used in either grid-connected or stand-alone configurations. Figure3 displays a structure of a system. The photovoltaic panel, cell battery, power converter devices, and control method are the essential components.


## 3.3. Photovoltaic Generator

PV modules are connected to the circuit, based on the power and voltage of the DC supply [19]. Monocrystalline or crystalline silicon photovoltaic modules were chosen because of their excellent quality and reduced depreciation over long durations when compared to other PV systems. The photovoltaic module is helpful to improve the quality of the generator. In it, the PV module was connected to the control bus. This control bus carried the control signals from the PV module to the inverter. This module was connected to the battery. The inverter circuit connects with the AC power supply. Then, the input current quality was enhanced by the PV module.


## 3.4. Cell Battery Storage

Due to repeated grid shortages, the battery unit includes static cells which can withstand a deep depletion, having a maxima cycle frequency surpassing 1000 times [20]. These lithium batteries offer high amp hour effectiveness of 80-90 percent as well as a high life expectancy of more than ten years. The ability of a battery is the size of the electricity stored within it, and it depends on the size of it. And it is determined by its lifetime depending on the nature of the term. The changes that are stored here are determined by its various standards.


## 3.5. Regulator of the Battery Charge

It is utilized to keep the battery building’s charging rate under control and safeguard it from overcharging and excessive overcharging. The value sensor is used to calculate the voltage levels and open or close switch S2 and per the battery’s state-of-charge, as indicated in Figure3.


## 3.6. Inverter 1 and Inverter 2

It is a grid-connected converter that converts PV generator DC source electricity to AC electricity exported to the grid. It features MPPT control techniques, management to kind the converter grid-connected, an anti-islanding technique to guarantee protection when a cutoff grid moments [21]. The bidirectional energy conversion can work as a converter to transfer DC to AC and also a radiator to transfer AC to DC electricity. In grid outages, it would deliver AC power to the demand as from battery blocks in the first mode. It functions as a converter in the second scenario; charge the battery component first from the grid throughout its levels of attention [22]. This converter is not intended to provide AC baseload power as from a battery bank. In the event of a grid shutdown, the reference signal Ig is primarily utilized to remove inverter 2.


## 3.7. Power Meter

This pattern is utilized to track how much energy is dissipated from a grid when serving the demand or charge the storage wedge, as well as how much electricity is exported to the grid from aPV scheme. This pattern was connected following the electricity law known as network monitoring.


## 3.8. PV System Design

The process measures will be considered while evaluating the planned PV system elements depicted in Figure3:
(i)
The daily global solar electricity production on flat surfaces is 5.4 kWh/m2 day, corresponding to the average maximum sunlight hours PSH=5.4h/day(ii)
In the city, the everyday consumption of electricity of a residential real estate and one publicly or privately utility is 10 kWh/day; this amount of energy indicates the consumption of a significant number of existing households and modest publicly or privately institutions daily [23]. Furthermore, the required installation surface of the equivalent PV generator is around 25 m2, allowing for easy deployment on a building roofing(iii)
To choose the right order for a particular voltage for our method, its publishing electronics should be given more than voltage. If so, it will use the stream lord. This may cause the risk of wasting power(iv)
The efficiency (ɳinv) of inverter 1 and inverter 2 is 94%, whereas the charging agency’s CR is 96%(v)
A block current battery maximum current effectiveness isɳBAh=85%(vi)
The DC system power is calculated at 48 V to keep the battery’s block voltage from exceeding a harmful level. The rate of heat transfer between two surfaces is equal to the temperature difference divided by the total thermal resistance between two surfacesTables1 and 2 show the detailed simulated findings for this position in terms of annual power output and consumption, as well as the quantity of yearly converters inefficiencies.Table 1
Yearly power production and consumption on a stand-alone system.
ConstructionkWh/yearPercentage (%)ConsumptionkWh/yearPercentage (%)Photovoltaic system1564100%AC primary demand432100%Overall1564100%Overall432100%Table 2
Yearly losses in electrical power in a stand-alone system.
MeasureConverterRectifierComponent unitsOperation hours64530hrs/yearPower in4630kWh/yearPower out4370kWh/yearLoss430kWh/year


## 3.9. Sizing of PV Generator

The highest power of aPV array generatorPPV is represented in
(4)PPV=EdPSH×ɳinv×ɳCR,while Ed seems to be the private house’s average power consumption (kWh/day), PSH seems to be the peak solar hours (hours per day), ɳCR represents charging controller effectiveness, and ɳinv is converter effectiveness.This can calculate the peak produced by the PV system in Watt peak (Wp) using the above model parameters represented in(5)PPV=100005.4×0.93×0.95=2096Wp.To ensure constant power is available throughout grid interruption hours and to account for cloudy weather as well as all voltage regulation losses, a PV generating with such a maximum output of 3200 Wp will be chosen [24]. Furthermore, boosting the PV peak output will ensure that the battery block maintains an acceptable state of charge. The PV module will be a polycrystalline module with 72 compartments that are related with such a peak output of 320 Wp. In this example, the PV generator will be made up of five series connections; that is, each is made up of two PV modules linked in series and has standard DC energy of 47 V, as illustrated in Figure 4 [25]. This energy is chosen to suit a battery storage block’s voltage level.Figure 4
PV generator.


## 3.10. Storage of Block Battery Design

When mounting the battery block in such an uptown building, the standard cell block power is calculated to be 48 V, which would be acceptable [26]. The storage space of the battery’s blocks would be chosen to fulfill the energy load requirements for a couple of days even without sunlight or the electricity supply. CBAh (total ampere hour) is calculated as follows:
(6)CBAh=Edb×ASDOD×VB×ɳBAh,where Edb is the everyday energy demand from the batteries (Ed/inv), DOD is a allowable penetration of discharge, AS is autonomy times, ɳBAh seems to be the batteries cell’s ampere hourly effectiveness, and VB seems to be the battery block’s chosen minimum DC voltage. The ampere hour load is calculated using actual values for various variables, such as AS=2.25days, DOD=0.8, and ɳBAh=0.85 and also VB=48V.
(7)CAh=1000/0.93×2.250.8×48×0.85=741.2Ah.A lead-acid battery block bank classified at800Ah/2V would remain chosen to a construct the loading solution that comprises 24 cells that are associated to offer a DC power supply of 48V/800Ah, to improve the battery energy storage stress distribution and to reverence, industry manufactured norm standards. This battery block has a battery performance of Cwh=19.2kWh, which would be suitable for interior placement in a household residence.


## 3.11. Regulator Charge Selection

The charge regulators would be evaluated at an input power in the region of 44-86 V and a voltage level of 3.2 kW, whereas its minimum voltage output is 48 V, taking into account the PV battery’s amount of voltage and maximum output.


## 3.12. Inverter Selection

Inverter 1 is still a 4 kVA only one DC/AC inverter that runs at a steady-state operation and has a dynamic performance of 220 V and 50 Hz, respectively [27]. As indicated in Figure 3, it provides the power supply via switch S1 and the power infrastructure with electricity generated by the PV generation via a bidirectional kWh-meter. This convertor is controlled by a system and developed to lock down in the event of a grid outage, ensuring total security.


## 3.13. Bidirectional Inverter Selection

It is a 5 kVA bidirectional inverter that was chosen to provide AC power from the storage block to demand while also generating electricity from a network when a PV power is restricted for the lengthy time, such as during wintertime.During conduction, heat is transferred through the vibration of molecules in a substance. As something gets warmer, it begins to increase the vibration and movement of the molecules that it consists of. In solids, particles are closely packed together and are in direct contact.


## 3.14. System Modes

The solar level of radiation, network disruption periods, the battery’s SOC, and autility grid are all variables that will cause the system to function in various modes [28]. Under some of these circumstances, the mechanism in Figure 3 will select the appropriate configuration from Table 3.Table 3
System operating modes.
ConfigurationSwitch 1Switch 2Description100Power cutoff, PV generation storing the batteries, and the cell blocks supplying electricity to the demand.210Grid connectivity is accessible, and load is drawn straight from the network.301The battery’s SOC is minimal, and a cellblock is supplied by both the PV system and the network at the same moment.411Grid connectivity, battery charge from the PV system, and surplus generated energy pumped into a network to supply the required. This state is not appropriate for this technology.


## 3.15. System Evaluation

The system simulations have been carried out using the given system design. Whenever the network is unavailable, the PV scheme and the stored power in the storage blocks were being utilized to fulfill a capacity demands [29]. During network available hours, its electricity would be used to meet power demands and fill the battery blocks, based on its charging condition. The simulation tool examines the energy requirements and PV energy output at every hour cycle and then decides whether to charge or discharge the batteries or infuse additional energy into the network regarding the difference.


## 3.16. Everyday Demand Curve

The load demand profile displays the load variance that is dependent on customer behavior. The main demands in a typical residential dwelling are lighting, television, computers, and household appliances including fridges, freezers, and dishwashers. As per Black’s Law Dictionary, “Residential dwelling means living in a certain place permanently or for a considerable length of time” as per Merriam Webster dictionary.In the computer simulation, the load profile indicated in Figure5 is taken into account [30]. The produced annually of PV energy system, the battery SOC, and the thermodynamic efficiency have all been evaluated using computer simulation depending here on everyday load profile illustrated in Figure 5.Figure 5
Typical everyday demand curve of a residential.


## 3.17. System Component Modeling

The objective of system modeling is to test the state’s performance under various settings and seasons. It is carried out utilizing PV array, battery, charge controller, and inverter numerical simulations [31]. Hourly meteorological data, temperature, and humidity and a load demand curve are used as input data. The calculation results give a quick summary of the mathematical methods.


## 3.18. Estimation of PV Power Output

PV maximum output at standard trial condition (STC), solar irradiance, and module temperatures are all important components in generating DC electricity from a photovoltaic system. This is an example of a simple design.(8)PPVout=PPVPeak×SSref×1+KTTc−Tref.From equation (8), where PPVout seems to be the PV array’s power factor, PPVPeak seems to be the PV element’s power at STC, Sseems to be solar energy in W/m2, Sref is represented as solar energy at STC of 1000W/m2, KT seems to be the thermal diffusivity of mono- and polycrystalline Si cells, KT=371031/°C,Tref is the source temperature at STC of 25°C, and Tc represents temperature coefficient estimated using a next econometric model.
(9)Tc=Tamb+0.0256×S,where Tamb represents the ambient temperature in equation (9).


## 3.19. Battery Storage Block

In the event of a grid failure or if the operation is performed in a stand-alone operation, a battery is created to gather the extra power generated by PV. They also continue to improve the demand whenever the PV power is insufficient to generate electricity. The following equations are being used to express the efficiency of charging and draining the battery blocks [32]. The rechargeable battery block has two modes of operation: charge and discharge. During charge controller in equation (10), the PV energy increased by the control authority’s effectiveness above the bidirectional inverter’s input signal inv2, which represents the power demand divided by inverter 2’s effectiveness. This power Pcharge would be increased by the battery’s charge effectiveness and then increased by one 60 minutes to contribute to the current battery charge (equation (11)). Since the simulation duration is one hour, the multiplying is by 60 minutes.The batteries will discharge powerPdischarge as during discharge mode (equation (12)) to compensate the deficit that occurs when the demand that exceeds a PV power. At cathode or positive electrode, due to oxidation, nickel hydroxide becomes, nickel ox hydroxide releasing water in the electrolyte solution. During charging of battery, the secondary battery turns to its original charged state and is ready for further discharging of battery. The energy released from the batteries is calculated by multiplying the PV power by a charging regulation performance, subtracting the power demand split by the bidirectional inverters effectiveness (inv2), and then dividing everything by the rapid charging effectiveness, as shown in (12). The discharge energy would be increased every 60 minutes, and the energy of a battery’s blocks would be deducted:
(i)
Charging operation(10)Pcharge=PPVO×ɳCR−PLɳinv×ɳBAh,(11)EBt=EBt−1+Pcharge×60minutes(ii)
Discharging operation(12)Pdischarge=PL/ɳinv−PPVO×ɳCRɳBAh,(13)EBt=EBt−1+Pdischarge×60minutes,where EB is the current battery energy generated (Wh), PPVO is the PV element’s power output (W), PL is a needed load energy (w), Pcharge is represented as voltage stimulating to a battery when charge controller (W), and Pdischarge is the energy discharge from batteries while discharging state (W). The rate of heat transfer to an object is equal to the thermal conductivity of the material the object is made from, multiplied by the surface area in contact, multiplied by the difference in temperature between the two objects, and divided by the thickness of the material.


## 3.20. Simulation Algorithm

The numerical methods presented above in this paper make up the system model. Figure6 depicts the experimental flow diagram. The application determines the MPP dimensions Imppf,Vmppf power output produced by the solar generator, or available energy during day and night utilizing weather information (solar insolation and temperatures), modules supplier information, and the condition of the electricity systems. This has used the MPP parameters Imppf,Vmppf at STC and the NOCT circumstances supplied by the company to assess the simulation program.
(i)
The PV scheme generates enough energy to meet the needs of the household. PV energy will take precedence over draining the battery and using the network if this is capable to satisfy load requirements [33]. If there is extra PV power, it will be pumped into the network or used to charge and discharge block under its state of charge(ii)
The PV power generated is insufficient to meet the load. If grid electricity is supplied, utilize it first; if grid services are not available, empty the maximum load of electricity from storage blocks(iii)
The amount of PV electricity produced is insufficient to meet the demand requirement, and the battery’s SOC is low. The grid can then be used to simultaneously charge and discharge blocks and fulfill the capacity demands(iv)
Grid stoppage intervals are, in reality, unpredictable in time and dependent on the state of the energy grid and cannot be determined by the PV user [34]. As a result, the model treats the PV scheme as a stand-alone system, and that is the worst-condition scenario. As a result, a software database depending on the flow chart is shown in Figure 6 is created to assess the network efficiencyFigure 6
Flow diagram.


## 4. Result and Discussion

The observed simulation results showed it during 9 months of every year, generated PV power surpasses the demand needs, resulting in a maximum battery state-of-charge (SOC) in an area. The performance of the PV-interfaced power converter’s topology functioning in charging mode is verified by simulation. The simulation findings are depicted and detailed in the previous figures.Figure7 depicts the PV system’s monthly power generation and the load’s monthly power usage. As during the 9 months of March to November, the energy generated by the PV outnumbers the energy used. The extra power production will be used to partially recharge the battery block and the remainder to supply the system. The PV electricity generated and the demand electricity demand are extremely close throughout the final three months, which validates the suitability of the executed PV system design, culminating in a PV peak output of 3.2 kW. Figure 8 depicts the system’s everyday energy production (kWh/kWp), which fluctuates across 2.6 and 5.4 kWh/kWp among January and July, respectively. This translates to 90% and 66.25% performance ratios, respectively. During the summer season, such as July, the performance index degrades because of better capacity PV power damages caused by relatively high temperatures.Figure 7
The PV system’s regular energy production.Figure 8
Average everyday yield and load usage.The annual battery SOC ranges among 42 and 86%, as seen in Figure9. It is worth noting that its minimum price remains above 40% including through the months with a weakest solar energy (Dec-Feb) and fluctuates between 73 and 84% during the remaining nine months, indicating that the battery’s design is correct. Figure 10 depicts the excess PV power generated over the connected load over nine months. When additional energy is available, it will either be pumped into the system or used to increase the SOC of a battery block, and it will be discarded then SOC ranges 100%.Figure 9
Block of battery SOC.Figure 10
Excess PV power on monthly.Figure11 depicts an hourly calculation of demand consumption of power, PV energy, and the SOC (percentage) for 3 days in April whenever output of PV is significant due to massive energy from the sun. The battery’s SOC remained steady, ranging between 77 and 93%. Figure 12 depicts the same system configuration on three days in December when the energy from the sun was minimal. The SOC drops to around 30% on such periods, as can be shown.Figure 11
Three days in the month of April.Figure 12
Three days in the month of December.The input variables are dependent on the preceding section’s predicted design parameters. The discharging cutoff level is the proportion of the fast charger below which the battery cannot be discharged. The discharge cutoff level is 30% since the release depth is 70%. Figure13 depicts the battery capacity of an intended off-grid device. According to the numerical simulations, the batteries remain powered up about 75% of the time over the year, with just 0.05% of the time having an empty cell, and also the amount of energy not absorbed owing to a set of batteries is 4371 Wh.Figure 13
Performance of battery on a stand-alone system.


### 4.1. Performance Ratio

The energy production to targeted power ratio is shown by the performance ratio (PR). The goal energy is calculated by multiplying total irradiation (kWh/m2) by a capsule’s STC effectiveness and actual implementation area (m2). PR indicates the losses caused by inverters, cable, shade, cell mismatches, reflections, blackouts, module heating, and other factors. The PR of a photovoltaic system deployed at the study location is measured by the 71.2% and 75% achieved in the preceding sections. According to the PV specifications, a PR of 80% or higher indicates a high-performing PV system, whereas several less than 75% suggest a concern. Nevertheless, in the instance of a building-integrated photovoltaic (BIPV) network, a PR of less than 75% may be considered acceptable. Due to increased temperature applications and the shielding impact, PR below 75% may be considered standard in the situation of a building-integrated PV (BIPV) network.


## 4.1. Performance Ratio

The energy production to targeted power ratio is shown by the performance ratio (PR). The goal energy is calculated by multiplying total irradiation (kWh/m2) by a capsule’s STC effectiveness and actual implementation area (m2). PR indicates the losses caused by inverters, cable, shade, cell mismatches, reflections, blackouts, module heating, and other factors. The PR of a photovoltaic system deployed at the study location is measured by the 71.2% and 75% achieved in the preceding sections. According to the PV specifications, a PR of 80% or higher indicates a high-performing PV system, whereas several less than 75% suggest a concern. Nevertheless, in the instance of a building-integrated photovoltaic (BIPV) network, a PR of less than 75% may be considered acceptable. Due to increased temperature applications and the shielding impact, PR below 75% may be considered standard in the situation of a building-integrated PV (BIPV) network.


## 5. Conclusion

In this research, the residential residence chosen for this research has a daily power consumption of 10k Wh/day, which equates to an everyday power range of 200 to 730 W. Depending on the modeling results, a photovoltaic system evaluated at 3.2 kWp with either a battery block volume of 19.2 kWh could cover the power the most of this residence. Over9 months of each year (Mar-Nov), the power produces by a PV system surpasses the load requirements, whereas it is nearly sufficient to the power of a charge even through three remaining months (Dec–Feb), when ultraviolet irradiance is at its minimum. These findings support the suggested PV system development’s ability to address power supply issues in residential applications. Furthermore, a PR of 71.2% is computed for a building integrating PV system at this location, whereas a PR of 75% is projected for a PV tracking system. The cause for this variation has been determined to be the ability of air circulation behind PV systems that was not constrained in the monitoring system, so increasing conditioning and thus modules effectiveness. The battery block state of charge changes in the area of 73-85% throughout 9 months (March–Nov) and 40-49% percent during 3 months (Dec–Feb), indicating that the suggested PV system can fulfill the demand requirements while retaining the batteries state-of-charge at an appropriate level. In January and July, a photovoltaic service’s daily energy produced ranges between 2.6 and 5.4 k Wh/kWp, corresponding to a conversion efficiency of 90% and 66.25%, correspondingly. In July, the decreased performance index shows the high-temperature difference experienced throughout the summer season.



---

*Source: 6202802-2022-05-20.xml*