Rooftop Grid-connected Photovoltaic Systems Research Articles

Peak Load Shaving of Air Conditioning Loads via Rooftop Grid-Connected Photovoltaic Systems: A Case Study

Over the past few decades, grid-connected photovoltaic systems (GCPVSs) have been consistently installed due to their techno-socio-economic-environmental advantages. As an effective solution, this technology can shave air conditioning-based peak loads on summer days at noon in hot areas. This paper assesses the effect of solely rooftop GCPVS installations on the peak load shaving of commercial buildings in arid regions, e.g., the Middle East and North Africa. To this end, the load profile of a large building with 470 kW of unshaved peak power in Mashhad, Iran (36.2972° N, 59.6067° E) is analyzed after commissioning an actual 51 kW GCPVS. The results of this experimental study, exploiting 15 min resolution data over a year, endorse an effective peak shaving of the GCPVS without employing a battery energy storage system, with 12.2–18.5% peak power shaving on a summer day at noon. The monthly GCPVS self-sufficiency is also 10.2%, on average. In accordance with the studied case’s results, this paper presents valuable insights and recommends actionable policies to regions with similar solar potential and electricity supply challenges, aiming to expedite GCPVS development.

Long-term performance of roof-top GCPV systems in central Viet Nam

In pursuit of the objective of achieving "net zero emissions," many countries worldwide, including Viet Nam, have prioritized the utilization of photovoltaic technology for energy conversion. Specifically, the implementation of roof-top grid-connected photovoltaic systems (GCPV) has emerged as a highly efficient solution in urban areas. These systems offer several advantages, such as minimizing land usage, lowering monthly electricity expenses, preventing building heat, generating income for households, and reducing transmission and distribution costs. This article focuses on a comprehensive long-term analysis conducted on 51 roof-top GCPV systems in the tropical monsoon climate of Hue City, Viet Nam, during the period from 2019 to 2023. The analysis findings reveal that roof-top GCPV systems with a capacity of 3-6 kW are well-suited for households in the central region of Viet Nam, characterized by a tropical monsoon climate. These systems exhibit an average sizing ratio of 1.03. The annual average daily final yield peaked at 3.28 kWh/kWp/day in 2021 and reached its lowest point at 2.97 kWh/kWp/day in 2022. Notably, the typical slope of the yield gradually increases with the installed capacity and the studied year. Furthermore, the monthly average daily final yield demonstrates a seasonal pattern, with higher yields observed from March to August and lower yields from September to January, aligning with the climate of the study area. As the years progress, the capacity factor and performance ratio of roof-top GCPV systems display a declining trend. Throughout the entire study period, these systems successfully mitigated 664 metric tons of CO2 emissions. The evaluation of long-term yield data offers valuable insights for photovoltaic installers, operators, and system owners, aiding in system maintenance and optimizing load utilization across different time periods. Long-term performance can be used by energy managers and owners of roof-top GCPV systems to identify supply shortfalls and initiate countermeasures.

Cost-reliability trade-offs for grid-connected rooftop PV in emerging economies: A case of Indonesia's urban residential households

This study explores the potential of grid-connected rooftop photovoltaic (PV) systems in terms of how they can be better planned and utilised by understanding possible trade-offs between cost and reliability while acknowledging challenges to utility supply security in the context of emerging economies. The study particularly examines the implications of unserved energy targets, PV capacity, and billing deduction factors on grid-connected rooftop PV's trade-offs in terms of total net present cost and unserved energy. This study considers four residential household segments in Indonesia's urban area as a case study, with four cases applied in each segment representing scenarios on PV capacities and billing deduction factors. Using HOMER software, the analyses highlight the role of cost components in trade-offs involving potential PV capacity cases. Systems with maximum PV capacity exhibit cheaper total net present costs than those of half PV capacity within the same unserved energy. While the optimisations pushed PV capacity up to the maximum size across all unserved energies, higher unserved energy resulted in lower grid capacity required to meet demand associated with the system's maximum unserved energy limit. This study provides residential customers and stakeholders with insights to better plan and implement grid-connected rooftop PV systems and policies.

Performance Analysis and Comparison of a 93.6 kW Grid-Connected Rooftop Photovoltaic System in South Tangerang

Performance Analysis and Comparison of a 93.6 kW Grid-Connected Rooftop Photovoltaic System in South Tangerang

Design of Grid-Connected rooftop Photovoltaic system for leakage current reduction using optimization algorithms

Rooftop solar power systems refer to the organization of photovoltaic (PV) panels on the rooftop of a building. They are a feasible substitute for land-based solar arrays, and they are being used in different Asian countries. Thus regulations, grid connectivity, off-take, and land acquisition are the main obstacles that renewable energy plant owners face. At high penetration of rooftop PV, this voltage variability reduces the stability of the grid due to transient imbalance in load and generation and causes voltage and frequency to exceed set limits if not countered by power controls. To reduce this power loss in the transmission cable, a Manta Ray Foraging Optimization (MRFO) process is presented in this research. This method also enhances the PV system's performance. A Non-isolated Buck-Boost Converter is connected between the PV and the grid. For renewable energy applications, a new non-isolated Buck-Boost converter with high voltage gain and positive output voltage has been developed. This converter receives the voltage of input from the PV and gives the output as boosting or lowering the voltage. To improve the current tracking with high power conversion efficiency, a Finite Control Set Model Predictive Controller (FCS-MPC) is introduced for this converter. The proposed optimization algorithm is utilized to tune the controller and improves the dynamic process of the power plant system connected to the grid. This algorithm is simulated using the Matlab Simulink software. The voltage and power generated by the proposed rooftop PV are 560 V and 495.25 kW/sec. The voltage and electricity produced by the ground-mounted are very low compared to the proposed method, therefore, utilizing this rooftop solar PV model, that study generates more power than the ground-mounted PV. This study contributes to the field by improving the energy production of roof-top solar PV systems based on roof design.

Techno-Economic Feasibility Assessment for the promotion of Grid-Connected Rooftop PV Systems in Botswana: A Case Study

The main aim of the present study is to investigate the solar energy potential and evaluate the economic viability of a 5kW grid-connected rooftop photovoltaic (PV) system as an electricity generation source in three selected regions (Gaborone, Maun, and Tshabong) in Botswana for the first time. In this study, NASA POWER data were used for evaluating the solar potential in the selected regions. The results showed that the selected locations are suitable for the installation of various scales of PV systems due to the high global horizontal solar radiation. RETScreen Expert software was used to assess the techno-economic feasibility of the proposed systems. The performance of the proposed systems with various PV technologies (mono-crystalline silicon and poly-crystalline silicon) is analyzed. Furthermore, economic and financial indicators such as net present value, annual life cycle savings, payback, benefit-cost ratio, and cost of energy production were calculated. The results indicate that the proposed system is very promising for all the selected locations. Additionally, it was found that the PV projects with poly-Si technology produced a large amount of energy and have a low electricity cost compared to mono-Si technology. The results suggest that grid-connected rooftop PV systems have a significant role in covering the electricity demand and in reducing carbon dioxide emissions, especially in high population density and rural regions. This study provides some useful recommendations for decision-makers regarding the development and deployment of PV energy technology in Botswana.

Economic and Environmental Analysis of Grid-Connected Rooftop Photovoltaic System Using HOMER

Economic and Environmental Analysis of Grid-Connected Rooftop Photovoltaic System Using HOMER

Economical sizing and multi-azimuth layout optimization of grid-connected rooftop photovoltaic systems using Mixed-Integer Programming

Solar energy is expected to be a significant contributor to meet the increasing global energy demand. Rooftop photovoltaic (PV) systems account for a substantial portion of the global solar energy potential. However, optimizing the size and layout of these systems remains challenging. Existing approaches either focus on maximizing energy generation, heavily restrict the space of potential layouts, ignore inverter-type implications, or neglect practical aspects, such as minimizing self-shading. This paper presents a mixed-integer programming (MIP) model to address these limitations for PV systems installed on flat rooftops. The proposed model optimizes the net present value (NPV) and can produce multi-azimuth layouts while accounting for practical considerations, including mitigating self-shading, and ensuring rooftop walkability. The proposed model is adapted for systems that utilize micro-inverters or string-inverters. Two case studies are conducted to evaluate the performance of the proposed model. In one case study, the model is applied to a residential area. It is numerically shown that in some instances of capital costs and billing policies, the use of multi-azimuth layouts could significantly improve the NPV compared to the use of single-azimuth layouts with parallel rows of panels. The proposed model solutions are compared to an existing optimized installation in the second case study. The proposed model multi-azimuth layout solution improves the NPV by 10.17%. When restricted to single-azimuth layouts, the proposed model produces the same design as that of the existing installation in only a few seconds.

Experimental and simulation analysis of grid-connected rooftop photovoltaic system for a large-scale facility

The growth of photovoltaic (PV) in developing countries remains a major challenge due to a lack of clarity on the performance of the grid-connected PV system. This paper illustrates some of the key features of the operating performance of the 81.9 kWp PV system installed on the roof of academic buildings. Real-time data was monitored over 12 months to evaluate the performance ratio, energy yield, efficiency, and losses associated with the system. The performance evaluation was done by PVsyst and was validated using the experimental data generated from the PV grid-connected system. The experimental result shows that the maximum final yield of 4.5 kWh/kW/day was obtained during April and the minimum of 2.4 kWh/kW/day was obtained during November. The annual average array and system efficiency was 13.1 % and 12.8 %, with July reported maximum efficiency of 13.4 % and 13.1 % respectively. The effect of high temperature and solar irradiance was observed in May, resulting in the lowest array efficiency of 12.6 %. System performance is seen to have seasonal implications, this was verified through simulation studies, and it was found that to overcome energy shortages, especially during winter seasons, PVsyst analysis predicts such shortcomings more accurately.

Optimal design of grid-connected rooftop PV systems: An overview and a new approach with application to educational buildings in arid climates

Recently, rooftop photovoltaic (PV) systems are widely deployed due to their technical, economic and socio-environmental benefits. This paper presents a new design approach, which combines spatial analysis with techno-economic optimization for a robust design and evaluation of the technical and economic potential of grid-connected rooftop PV (GCR-PV) systems, focusing on educational buildings in arid environments. A university campus in Ouargla province in Algeria is selected as a test-bed in this work. The main objectives of this work are to reduce the cost of energy (COE), grid dependency and CO2 emissions, and even contribute to limit grid blackouts in the building location. Ecotect software, ArcGIS, and HOMER optimizer were therefore used to achieve the contributions of this work. The findings reveal that 60% of the overall roof area is optimally suitable for hosting PV panels. Considering only this optimal area, multi-crystalline PV panels with an inclination of 17° yield the highest annual electricity output (2333.11 MWh/year). Based on this configuration, a sensitivity analysis is then performed to study the effects of feed-in tariffs (FITs) and the cost of components in the system outcomes. It is observed that with FITs less than those applied to large-scale PV projects in Algeria (0.11 $/kWh), the analyzed GCR-PV system has fulfilled high self-sufficiency, reaching grid parity (COE 0.043 $/kWh) and exporting significant amounts of electricity to the grid. Accordingly, the feasibility of the developed approach and the techno-economic viability of the GCR-PV system are both demonstrated.

A Techno-Economic Comparative Study of a Grid-Connected Residential Rooftop PV Panel: The Case Study of Nahr El-Bared, Lebanon

Lebanon suffers from daily electricity shortages. The country has paid much attention to renewable energy sources, particularly solar, to gradually replace conventional energy. Installing a photovoltaic (PV) system becomes increasingly attractive for residential consumers due to the rising electricity tariff rates while it reduces the dependency on domestic power generators. No known study has dealt with the investigation of potential grid-connected rooftop PV systems with various sun-tracking modes and PV technologies in Nahr El-Bared, Lebanon. Consequently, the main objective of the current paper is to investigate the feasibility of a 5kW grid-connected PV system of various technologies (mono-crystalline silicon and poly-crystalline silicon) and sun-tracking modes including fixed tilt and 2-axis systems for rooftop households in Lebanon. The Nahr El-Bared camp was the case study was of the paper. RETScreen Expert software was used to evaluate the techno-economic performance of the proposed systems. The results show that the annual electrical energy from a fixed 5kW PV panel tilted at an optimal angle ranged from 8564.47kWh to 8776.81kWh, while the annual electrical energy from the PV tracking system was within the range of 11511.67-12100.92kWh. This amount of energy output would contribute significantly to reduce the energy shortage in the country. A typical household was selected to establish a load profile and load supply during both grid availability and outage periods. The highest energy consumption that can be covered by the PV systems was recorded during the spring and summer seasons. Also, the average energy production cost ranged from 0.0239 to 0.0243$/kWh for all the proposed systems. It was concluded that a 5kW grid-connected rooftop PV system could be economically justifiable. Finally, this study tried to increase the awareness about utilizing PV sun-tracking systems and the feasibility of small-scale grid-connected rooftop PV systems in the selected regions. The results of this research can help investors in the energy and building sectors.

Characteristics of harmonic distortion and disturbance in frequency 9-150 kHz of the grid-connected rooftop photovoltaic system for various types non-linear household loads

The usage of Photovoltaic (PV) energy system as a solar power plant has been growing rapidly in the world, because it is clean without emitting greenhouse gasses. The rapid development of power electronics technology has an impact in the development of PV system and the usage of non-linear household appliances that use inverter technology. In PV system, an inverter is used to convert direct current (DC) power from sunlight to alternating current (AC). Inverters usually have a switching rate higher than 1 kHz, which may cause waveform distortions and disturbances in AC power output, such as harmonics and disturbance in the frequency range 9-150 kHz. These disturbances may affect the performance of equipment, as well as neighbor equipment connected to the same network. This research is focused on analyzing the effect of current flowing in the non-linear household loads (induction cooker and compact fluorescent lamp) to the harmonics distortion (THDi, TDDi and harmonic voltage distortion) and disturbance in frequency 9-150 kHz on the Grid-connected Rooftop PV System by conducting laboratory measurement using a computer-based oscilloscope and power quality analyzer. The results show that the variation of current flowing in the equipment affects the harmonics distortion and disturbance in frequency 9-150 kHz.

The Possibility of Generating Electricity Using Small-Scale Wind Turbines and Solar Photovoltaic Systems for Households in Northern Cyprus: A Comparative Study

The increased energy demand and related environmental problems caused by burning fossil fuels have raised interest in alternative energy sources. This study investigated the wind characteristics and available wind energy for three urban regions in Northern Cyprus using the Weibull distribution function. The results illustrate that Gazimağusa is the most applicable location for harvesting the kinetic energy of the wind compared to Lefkoşa and Girne. Moreover, the solar potential at a specific location can be analyzed using a different simulation tool. In the present paper, the performance of a rooftop Photovoltaic (PV) system for household buildings in three selected is assessed. Three types of simulation software (PVGIS, PV*SOL, and PVWatts) are used to evaluate the performance of the 6.4 kWp grid-connected rooftop PV system. This study assessed the energy generation, performance ratio and capacity factor for this PV system. The results concluded that PVGIS is an easy, fast, and reliable software tool that can be used for the simulation of a solar PV system in the studied regions. Furthermore, an economic evaluation of renewable systems in the three urban regions is presented. As a result, a small-scale grid-connected solar/wind system that is able to generate electricity with an excellent percentage of clean energy was proposed and developed. The analysis indicates that the proposed PV projects showed significant potential in the studied locations. In addition, the proposed PV system is the most economical option for generating electricity compared to wind systems due to the low electricity prices and of the ability to recover the initial investment. Consequently, it is expected that the simulation results will help in demonstrating the advantages and challenges of installing grid-connected PV systems for households in Northern Cyprus in order to reduce the electricity consumption produced by fossil fuels.

DA-DCGAN: An Effective Methodology for DC Series Arc Fault Diagnosis in Photovoltaic Systems

DC arc faults, especially series arcing, can occur in photovoltaic (PV) systems and pose a challenging detection and protection problem. Machine learning-based methods are increasingly being used for fault diagnosis applications. However, the performance of such detection algorithms will degrade because of variations between the source domain data used during the development and the target domain data encountered in operation of the field. Furthermore, the fault’s data in the target domain for model training are usually not available. In this paper, domain adaptation combined with deep convolutional generative adversarial network (DA-DCGAN)-based methodology is proposed, where DA-DCGAN first learns an intelligent normal-to-arcing transformation from the source-domain data. Then by generating dummy arcing data with the learned transformation using the normal data from the target domain and employing domain adaptation, a robust and reliable fault diagnosis scheme can be achieved for the target domain. The PV loop current is framed and arranged into a 2D matrix as input for cross-domain DC series arc fault diagnosis. The system is validated offline using pre-recorded PV loop current data from a real 1.5-kW grid-connected rooftop PV system. Also, the proposed method is implemented in an embedded system and tested in real-time according to UL-1699B standard. The experimental results clearly demonstrate benefits of DA-DCGAN and confirm the effectiveness of the proposed methodology for practical PV applications.

Life Cycle Ecological Footprint Assessment of an Academic Building

Buildings are responsible for significant natural resource consumption, waste generation and environmental pollution. Building impacts are generally assessed through life cycle analysis (LCA). This study integrates LCA with the Ecological Footprint indicator for the assessment of a building’s impact on the planet. In order to determine ecological impact of a building, a methodology has been established for the estimation of life cycle ecological footprint (LCEFtotal) of the building, as well as to assess its impact due to resource consumption (energy, water, building materials, manpower, etc.) and waste assimilation over the life cycle. For an academic building located in India taken as a case study, the LCEFtotal is found to be 4426.47 gha and the LCEFtotal per unit floor area is 0.6 gha/m2. The average annual Ecological Footprint (EFavg) of the academic building has been estimated as 73.77 gha/year, that is, approximately 101 times more than the built-up land of the academic building. For the academic year of 2015–2016, the average annual Ecological Footprint per student (EFavg/student) of the academic building is 0.05 gha/student-year. If annual grid electricity consumption of the building is replaced by the grid-connected rooftop photovoltaic system in the ratios of 100%, 75%, 50% and 25%, it can be reduced up to 61%, 46%, 31% and 15% of the total LCEFtotal of the academic building, respectively.

Optimal sizing of residential PV-systems from a household and social cost perspective: A case study in Austria

In this paper we analyse optimal sizing of grid connected rooftop photovoltaic systems from a household’s perspective. We estimate the profit maximizing size for more than 800 households in Austria for various electricity tariffs and subsidy schemes considering economies of scale related to the investment costs of photovoltaic systems in the size range of 1–20kW of installed capacity. Size dependent investment costs are estimated from data on photovoltaic systems installed in Austria from 2008 to 2013. We then take a social cost perspective and relate the results to the total investment costs to install a certain amount of capacity in residential areas. We find that in the presence of economies of scale substantial cost inefficiencies can occur resulting from incentives to install relatively small systems. Depending on the compensation scheme the simulated optimal system size can be as low as 2kW resulting in high costs per capacity. Subsidy design and tariff regulations can be adopted to incentivize larger photovoltaic systems in the residential sector which would reduce the costs of achieving a certain level of distributed PV generation. It is estimated that for a minimum system size of 5kW total investment costs for subsidised residential photovoltaic systems in Austria from 2008 to 2013 could have been 2.2% lower for the same amount of installed capacity. We further argue that the strict focus on onsite use of electricity from photovoltaic systems in the residential area is not necessarily desirable from a social cost perspective because it can lead to small and therefore more expensive photovoltaic systems.

Solar photovoltaic (PV) energy; latest developments in the building integrated and hybrid PV systems

Environmental concerns are growing and interest in environmental issues is increasing and the idea of generating electricity with less pollution is becoming more and more attractive. Unlike conventional generation systems, fuel of the solar photovoltaic energy is available at no cost. And solar photovoltaic energy systems generate electricity pollution-free and can easily be installed on the roof of residential as well as on the wall of commercial buildings as grid-connected PV application. In addition to grid-connected rooftop PV systems, solar photovoltaic energy offers a solution for supplying electricity to remote located communities and facilities, those not accessible by electricity companies. The interest in solar photovoltaic energy is growing worldwide. Today, more than 3500 MW of photovoltaic systems have been installed all over the world. Since 1970, the PV price has continuously dropped [8]. This price drop has encouraged worldwide application of small-scale residential PV systems. These recent developments have led researchers concerned with the environment to undertake extensive research projects for harnessing renewable energy sources including solar energy. The usage of solar photovoltaic as a source of energy is considered more seriously making future of this technology looks promising. The objective of this contribution is to present the latest developments in the area of solar photovoltaic energy systems. A further objective of this contribution is to discuss the long-term prospect of the solar photovoltaic energy as a sustainable energy supply.