光伏阵列安装角度与安装节距的优化选择

光伏发电系统安装地点确定之后,其发电量主要受到光伏组件安装倾角和节距的影响。文章首先建立了光伏电池发电模型和斜面上的辐照度模型,以西安某公司的光伏发电系统为例,计算了不同倾角和节距下光伏阵列的年发电量。结果表明:在没有阴影遮挡的情况下,光伏组件在西安地区的最佳安装倾角为32°;在有阴影遮挡的情况下,节距越小,最佳倾角越小。光伏阵列的节距减小时,组件的发电量减少,利用效率降低。但是,由于组件安装量增多,单个组件占地面积减少,总安装容量增大,发电量增大。此计算方法可为光伏组件安装倾角和节距的选择提供参考。     

失配条件下集中式并网光伏发电系统性能研究

为分析光伏系统在失配条件下的运行性能,首先对阴影遮挡下的集中式光伏阵列模型进行理论推导,其次采用PVsyst仿真软件仿真石林地区500 kW光伏系统在当地自然气候条件下倾角、方位角和阴影遮挡对全年发电性能的影响。最后对比分析石林光伏系统的仿真结果与实测结果,并提出优化方案。结合理论模型分析进行的仿真结果显示,无阴影遮挡时,在倾角等于纬度角、方位角等于0°时,光伏系统年发电量最大,为704 MWh,性能比高达80.1%。而在相同线性阴影遮挡下,随倾角变化,系统性能比降幅范围为1.0%~24.9%。实测结果表明,无阴影遮挡下,实际系统发电量与平均气象参数下的仿真系统相比下降20%,有阴影遮挡时下降17%;而相同气象数据下,实测结果与仿真结果误差仅为0.01~0.30。集中式并网光伏发电系统(GCPVS)性能在合理安装倾角、方位角下能有效降低系统失配损失,而多云、阴影遮挡等辐照度不均匀会增加集中式拓扑结构下光伏系统的失配损失,需通过优化系统配置或最大功率点跟踪技术来避免。     

吕梁市光伏发电系统效率提升研究

对影响光伏发电系统发电量的因素进行了研究,通过实验方法确定了倾角、方位角和局部阴影遮挡对吕梁市光伏组件发电量的影响.结果表明:在接近地理纬度的角度范围内,倾角对光伏组件发电功率的影响在12％左右;调整方位角对光伏组件功率的影响较大,在合理跟踪方位角的情况下,可使光伏组件发电功率增长1倍;遮挡对光伏组件的发电功率影响很大...     

积灰阴影遮挡对光伏发电系统的影响

阐述了太阳能光伏电池积灰的成因、积灰的物理及化学性质和形态分类,解释了积灰的遮挡效应、腐蚀效应和热斑效应,应用MATLAB应用软件搭建光伏电池及光伏发电仿真系统,研究积灰阴影遮挡对光伏发电系统的影响。分析光伏发电系统的原理,利用MATLAB建立光伏发电系统模型,利用搭建好的模型针对光伏组件的积灰与局部阴影来进行仿真,用定性和定量分析积灰与阴影遮挡对光伏组件及其发电系统的影响,指出了对于光伏板组件上积灰清洗的重要性。     

应用于高原山地光伏电站的平单轴光伏发电跟踪系统的优化

对应用于高原山地光伏电站的平单轴光伏发电跟踪系统进行了优化研究.高原山地光伏电站因采用平单轴光伏发电跟踪系统时,清晨和傍晚太阳高度角较低时前、后排光伏组串会相互产生阴影遮挡,由此现象入手,从反阴影遮挡跟踪策略、平单轴光伏发电跟踪系统对其基础的破坏、平单轴光伏发电跟踪系统可靠性等方面分析了目前采用的常规平单轴光伏发电跟踪...     

考虑阴影影响的光伏电池组件实验研究

太阳能足一种清洁的能源,利用太阳能发电是其中一种利用方式.目前建设太阳能发电系统成本还是较高,从我国现阶段的太阳能发电成本来看,约占光伏电池组件费用的60%～70%[1,2]一般情况下,计算发电量是在太阳能方阵面完全没有阴影的前提下.因此,如果光伏电池不能被日光直接照射,而只有散射光用来发电,此时的发电量比无阴影时减少约10%～20%[3,4].     

会泽县六合光伏电站的优化设计与分析

云南省会泽县是中国太阳能资源最丰富的地区之一，光伏电站将成为该县经济与社会发展的支柱产业。基于提高光伏发电效率、降低成本、确保运行安全的设计原则，对位于该县六合村的六合光伏电站的设备选型和光伏阵列设计进行优化。通过市场调查和分析，确定光伏组件、逆变器和光伏支架的类型；基于SloarGIS气象数据库，利用PVsyst软件分析光伏组件接收的年总太阳辐射量与光伏组件安装倾角的关系，确定最佳安装倾角；根据地形坡面、太阳光线和光伏组件之间的几何关系，推导任意坡面下的理论光伏阵列间距，并利用Helios-3D软件分析实际地形下光伏阵列之间的阴影遮挡规律，实现光伏阵列的无阴影遮挡布置；基于光伏组件的质量标准，预测光伏电站年发电量。分析结果显示：光伏电站建成后预计25年总发电量为6253901.2MWh；年平均发电量为250156.0 MWh。     

阴影遮挡下光伏组件横竖向放置对发电量的影响

为了提高阴影遮挡时光伏组件的发电量,针对横、竖向放置时光伏组件相互遮挡产生的功率损失,建立了光伏组件在阴影遮挡情况下的数学模型,考虑了光伏组件并联旁路二极管的影响,仿真模拟了阴影遮挡下横、竖向放置时光伏组件的输出特性,进而以某地100kW光伏阵列为例,计算了光伏组件在不同摆放方式、不同倾角与间距下的辐射量、年发电量、阴影损失及年平均效率,为光伏电站的初步设计提供了一定的参考价值。     

北京地区多种光伏组件发电性能对比实验研究

该课题组设计建造了一座光伏试验电站,对单晶硅光伏组件、多晶硅光伏组件、非晶硅光伏组件、铜铟镓硒光伏组件和碲化镉光伏组件进行长期监测,对监测数据进行统计并分析了温度、弱光和湿度对不同光伏组件的影响,设计了阴影遮挡试验和灰尘清洗试验。研究表明,薄膜光伏组件的温度效应优于晶硅光伏组件,其输出功率损失低于晶硅光伏组件;对于晶硅光伏组件由于表面积尘和阴影遮挡而引起的输出功率损失要高于薄膜光伏组件;而弱光和湿度对光伏组件发电性能的影响没有明显差异。通过分析试验电站的监测数据,发现铜铟镓硒光伏组件单位装机容量的发电量最高,其发电量高出多晶硅光伏组件5.72%,而次于铜铟镓硒光伏组件发电能力的是单晶硅光伏组件和多晶硅光伏组件。     

逆跟踪技术在平单轴跟踪器上的应用

研究逆跟踪技术在平单轴跟踪器中的应用,分析逆跟踪技术对于平单轴光伏系统发电的提升优势,以及节省占地面积的优势,结合仿真模型验证逆跟踪技术在平单轴跟踪系统中的发电优势和占地面积优势。研究结果表明,在不增加用地面积情况下,应用逆跟踪技术能避免光伏阵列内部的阴影遮挡,降低发电量损失,使平单轴跟踪系统发电更高效,单位面积的发电更多。     

Analysis of spatial fixed PV arrays configurations to maximize energy harvesting in BIPV applications

This paper presents a new approach for efficient utilization of building integrated photovoltaic (BIPV) systems under partial shading conditions in urban areas. The aim of this study is to find out the best electrical configuration by analyzing annual energy generation of the same BIPV system, in terms of nominal power, without changing physical locations of the PV modules in the PV arrays. For this purpose, the spatial structure of the PV system including the PV modules and the surrounding obstacles is taken into account on the basis of virtual reality environment. In this study, chimneys which are located on the residential roof-top area are considered to create the effect of shading over the PV array. The locations of PV modules are kept stationary, which is the main point of this paper, while comparing the performances of the configurations with the same surrounding obstacles that causes partial shading conditions. The same spatial structure with twelve distinct PV array configurations is considered. The same settling conditions on the roof-top area allow fair comparisons between PV array configurations. The payback time analysis is also performed with considering local and global maximum power points (MPPs) of PV arrays by comparing the annual energy yield of the different configurations.     

Performance enhancement of partially shaded solar PV array using novel shade dispersion technique

Solar photo voltaic array (SPVA) generates a smaller amount of power than the standard rating of the panel due to the partial shading effect. Since the modules of the arrays receive different solar irradiations, the P-V characteristics of photovoltaic (PV) arrays contain multiple peaks or local peaks. This paper presents an innovative method (magic square) in order to increase the generated power by configuring the modules of a shaded photovoltaic array. In this approach, the physical location of the modules in the total cross tied (TCT) connected in the solar PV array is rearranged based on the magic square arrangement pattern. This connection is done without altering any electrical configurations of the modules in the PV array. This method can distribute the shading effect over the entire PVarray, without concentrating on any row of modules and can achieve global peaks. For different types of shading patterns, the output power of the solar PV array with the proposed magic square configuration is compared with the traditional configurations and the performance is calculated. This paper presents a new reconfiguration technique for solar PV arrays, which increases the PV power under different shading conditions. The proposed technique facilitates the distribution of the effect of shading over the entire array, thereby, reducing the mismatch losses caused by partial shading. The theoretical calculations are tested through simulations in Matlab/ Simulink to validate the results. A comparison of power loss for different types of topologies under different types of shading patterns for a 4×4 array is also explained.     

Reliable and efficient approach for mitigating the shading effect on photovoltaic module based on Modified Artificial Bee Colony algorithm

The operation and performance of a photovoltaic system (PV) are affected by some factors such as; solar radiation, ambient temperature, PV array configuration and shadow which may be either completely or partially. The partially shadow is caused by clouds, trees due to wind, neighboring buildings and utilities. The shadow effect causes the multiple local maximum power points in the PV module voltage-power characteristics and only one Global Maximum Power Point (GMPP); additionally the shadowing causes high power loss in the shaded cells and produces hot spot. In this paper a new optimization approach based on proposed Modified Artificial Bee Colony (MABC) algorithm is used to solve a proposed constrained objective function of PV module power loss and mitigate the shading effect. The proposed MABC is compared with GA, PSO and ABC. The obtained results proved that the MABC is the most efficient algorithm in solving the objective function that mitigating the power loss in the PV module under partially shading effect.     

基于S-V特性分析的晶硅光伏组件阴影遮障诊断

针对广泛使用的晶硅光伏组件,通过Simulink建立太阳电池双二极管精确仿真模型,对实际应用中最常见的光伏组件阴影遮挡故障进行多种工况的仿真验证。根据I-V曲线拐点、台阶、曲线下积分面积（S）下降的特征,提出一种基于S-V曲线特性的光伏组件阴影遮挡故障的在线诊断方法。该方法建立S-V曲线,根据S-V曲线分叉点位置可判断光伏组件遮挡情况,通过整体积分面积进而判断遮挡比例。对温度、辐照度进行折算,使该方法在全工况下适用。结合光伏组件功率优化器验证该诊断方法有较高的准确率,并且可准确地判断阴影遮挡面积,具有很高的实际应用价值。     

Comparative study and performance evaluation of central and distributed topologies of photovoltaic system

In this paper, we present a new alternative for improving both the performance of photovoltaic (PV) systems and the efficiency of the energy conversion by using different configuration of power converters. For this purpose, a comparative study between two configurations is carried out. The first configuration consists of a classical PV generator with a single centralized high power converter and the second one concerns a distributed topology. For this latter we use a certain number of PV strings with low power converters attached in series, in parallel or in a combination of series and parallel. Obviously the string topology has some advantages. Each power converter can control the power conversion of each module individually, which results in increased overall energy conversion of the entire system. The MPPT control system in this case can react effectively to atmospheric variations, to shading effect and to changes in the load. The PV system still operates even in case of failure on one of the power converters in a string. We simulated and compared the different conversion configurations in order to find the best one in terms of efficiency and produced energy. The obtained results are very interesting and can lead to optimal sizing and selection of best PV topology for a given application.     

A high efficiency photovoltaic module integrated converter with the asymmetrical half-bridge flyback converter

A module integrated converter (MIC) for a photovoltaic (PV) cell is important part of power conditioning system (PCS). It performs maximum power point tracking of a PV cell to generate the power as much as possible from solar energy. There are several methods for connection between the PV modules and the MICs. In order to avoid partial shading effects, converter-per-module approach was proposed. The MIC that performs maximum power point tracking (MPPT), if it is low efficiency, is no use. The MIC whose output is connected to the output of PV module was proposed for high efficiency. However, there are some problems. In this study, an asymmetrical half-bridge flyback converter is proposed instead of the original flyback converter with same method to solve the problems. The proposed MIC was built to verify the performance. The new topology using soft switching technique showed good performance for the efficiency. At the higher power, the efficiency of the proposed converter is higher than existing converter.     

Self-shading losses of fixed free-standing PV arrays

The energy yield of a photovoltaic (PV) system with fixed free-standing PV arrays is affected also by the self-shading effects. The rows of PV modules in arrays may partially shade the PV modules in the rows behind. In this paper the effects of the row distance on the PV system’s energy yield are evaluated. The estimation of the self-shading losses by the irradiation losses simply overestimates the losses; therefore we developed a simulation model to simulate the real energy loss due to shading of the preceding row in a PV system. The model demonstrates that the self-shading energy losses are at commonly used distances between rows from 20 to 40% lower than the irradiation losses at the modules’ bottom considering the shading conditions. The self-shading energy loss is studied in the case of Ljubljana, Slovenia which may refer to the whole Central Europe. To estimate the self-shading losses a technology-and with parameter modifications also location-independent empirical equation based on module-to-cell width ratio was derived and validated.     

Integrating photovoltaic and power converter characteristics for energy extraction study of solar PV systems

Solar photovoltaic (PV) energy is becoming an increasingly important part of the world’s renewable energy. A grid-connected solar PV system consists of solar cells for energy extraction from the sun and power converters for grid interface. In order for effective integration of the solar PV systems with the electric power grid, this paper presents solar PV energy extraction and conversion study by combining the two characteristics together to examine various factors that may affect the design of solar PV systems. The energy extraction characteristics of solar PV cells are examined by considering several practical issues such as series and parallel connections, change of temperatures and irradiance levels, shading of sunlight, and bypassing and blocking diodes. The electrical characteristics of power converters are studied by considering physical system constraints such as rated current and converter linear modulation limits. Then, the two characteristics are analyzed in a joint environment. An open-loop transient simulation using SimPowerSystem is developed to validate the effectiveness of the characteristic study and to further inspect the solar PV system behavior in a transient environment. Extensive simulation study is conducted to investigate performance of solar PV arrays under different conditions.     

An adaptive utility interactive photovoltaic system based on a flexible switch matrix to optimize performance in real-time

Reconfigurable architectures are of great interest to system designers to improve the system’s operation and efficiency. In this paper, we propose an adaptive utility interactive photovoltaic (PV) system based on a novel Flexible Switch array Matrix topology. This proposed system maximizes the generated power in real-time in response to operational conditions such as shading, soiling, mismatches, and module failure among others. The proposed system is a compromise in the utilization of power conditioning equipment to maximize energy capture and system efficiency. Simulation results demonstrate an average 13% improvement in efficiency when compared with the central inverter topology performance. A prototype system has been designed and tested. The experimental results validate the proposed topology and its benefits for a wide range of applications.     

Estimation of rooftop solar photovoltaic potential using geo-spatial techniques: A perspective from planned neighborhood of Karachi – Pakistan

With an ever increasing population and significant solar resource availability throughout the whole year, Karachi metropolis hold a promising rooftop solar photovoltaic (PV) potential considering its millions of urban households. This research work highlights techniques to combine geographic information systems (GIS) and object-based image recognition approach to identify the available rooftop area for PV deployment in a small scale region of DHA Phase 7 Karachi. A six step methodology has been adopted for the estimation of rooftop PV potential which involves geographic division of high resolution satellite imagery; sampling and rooftop feature extraction using FE tool of ENVI EX software; extrapolation of rooftop areas for the entire ROI using roof area-population relationship; visual inspection to analyze different rooftop factors such as building orientation, shading effect from trees and nearby buildings and other roof uses; a comparison of extracted rooftops to the physically measured sample rooftops, reduction for shading and other uses; and finally conversion to energy and power outputs. A relationship of total roof area and population of 13 m²/capita ±5% has been found. With higher efficiency rooftop PV panels, 12.24 MW of solar power can be generated which is 122.4% of peak power demand of DHA Phase 7.