不同支架结构遮挡对双面光伏阵列年发电量的影响分析

针对在实际安装中，固定支架的主轴会对双面组件背面产生一定比例遮挡的问题，建立基于光交检测算法的视角系数模型对双面组件背面辐照度进行更细致化、定量化的模拟。不均匀辐照度主要体现在每块电池片的背面辐照度不同，将热电耦合模型细化到电池片，解决双面组件在背面遮挡条件下的失配损失计算，完成双面组件在复杂工况下的建模工作。结合调研案例，以15年为投资周期，对比固定支架的3种主梁结构（常规支架、双主梁支架、单主梁支架）下双面光伏阵列的发电量及经济性，最终得出采用单主梁结构支架的双面光伏阵列年发电量净增益最大且经济效益最优的结论。     

双面光伏组件建模及发电性能研究

针对双面光伏组件建立一种耦合模型,可用于模拟双面光伏组件在实际运行过程中的输出特性。采用视角系数法建立便于模拟背面辐照度的二维辐照度模型,提出一种简化计算方法来求解七参数电学模型,并根据能量守恒的非稳态热学模型来估计电池温度。之后通过输入参数的传递,对耦合模型进行求解,并通过实验数据验证模型的准确性。结果表明：辐照度模型可对不同天气条件下双面光伏组件辐照度进行模拟,晴天时更准确,均方根误差仅为6.9%;采用简化方法求解的七参数电学模型,求解结果与实测值较吻合,在最大功率处的功率偏差仅为0.4 W;所建立的耦合模型可对双面光伏组件单日输出功率及年度发电性能进行评估,模拟结果与实测数据吻合较好。     

双面光伏组件辐照度模型的研究

针对双面光伏组件正面和背面获均能吸收太阳光的特点,通过光线跟踪辐照度模型分析,构建区分阴影区和无阴影区的热传输理论视觉因子太阳辐照度模型。模拟结果表明:当双面光伏组件倾斜角比单面组件增加约4°,在地面反射率为30%和50%的情况下,年辐照度增益可提高17.41%和28.79%;且随着离地高度与行间距增加,年辐照度可进一步提高。双面光伏组件辐照度模型为双面光伏组件电站安装时的地面反射率、最佳倾斜角、离地高度及行间距的设置提供了理论支撑。     

一种新型双面光伏组件正面和背面太阳辐照测试系统的介绍

提出了一种双面光伏组件正面和背面太阳辐照测试系统及测试方法,通过将理论值与实测值等进行对比,发现该测试系统及方法可解决现有技术中不能精确测量双面光伏组件正面和背面辐照度及辐照量的问题。     

光伏组件辐照度增益研究

为有效分析双面光伏组件、平单轴跟踪技术较固定倾角单面光伏组件的辐照度的增益,通过固定倾角和平单轴视日运行轨迹分析,利用视觉因子方法,构建平单轴双面光伏组件辐照度模型。通过测试与分析,当组件阵列宽度为2 m、行间距为5 m、组件离地高度为2 m、地面反射率为0.2、双面系数为0.75的情况下,杭州地区的双面、平单轴、平单轴双面的辐照度增益分别为0.076、0.078、0.161;此外,当水平散射辐射量占比越高,双面增益越明显,水平直射辐射量占比越高,平单轴增益越明显。为不同地区的平单轴、双面光伏组件的安装与应用,提供理论指导。     

一种反射聚光的双面光伏发电装置的设计研究

目前双面光伏电池发展迅速,但是双面光伏电池组件的背面光线差,发电效率低.为了提高双面光伏电池组件的发电量,通过对平面镜反射聚光原理的分析,得出了光线反射强度的变化规律.采用双平面镜反射光叠加后,光伏板倾角从0°增大到60°时,两镜总反射光强度系数从1.12增大到1.71,平均发电量可提高1倍以上.据此设计了一种双平面镜...     

不同地面背景对双面光伏组件发电性能的影响

以双面光伏组件为研究对象,通过理论计算和实验研究的方法,对双面组件在不同地面背景下的发电性能进行理论分析与实验验证。研究结果表明:双面组件的功率增益随地面背景的反射率增大而增大,随辐照度增加而降低,双面组件在反射率最大的铝箔地面与反射率最小的草坪地面的最大功率增益分别为25.30%和8.24%。     

双面光伏组件背面无遮挡时的发电量研究

针对以常规方式安装双面光伏组件时组件背面存在一定遮挡会影响其发电量这一情况,通过对双面光伏组件分别安装于固定式光伏支架、平单轴跟踪光伏支架时组件背面有、无遮挡,以及背景反射率不同时双面光伏组件的发电量情况进行分析,结果发现,在双面光伏组件背面无遮挡的前提下,当采用平单轴跟踪光伏支架且地面背景为白色时,双面光伏组件的发电...     

单面和双面单晶硅光伏组件的发电性能实证

针对p型PERC单面单晶硅光伏组件和n型双面单晶硅光伏组件,利用光伏组件户外实证测试系统,分析了2016年12月15日～2018年7月20日期间,上海市嘉定区某屋顶的地面采用白板背景时双面和单面组件,以及水泥背景时双面组件的等效发电时长,并对白板背景和水泥背景时双面组件较单面组件的发电量增益情况进行了分析;计算了组件的PR值;分析了阴天和晴天时组件最大输出功率与组件背板温度、太阳辐照度和环境温度的关系;最后对比了单面和双面组件运行13个月后的衰减值。该实证结果为单面和双面组件的户外实证发电性能提供了数据支撑,并对双面组件较单面组件的发电量增益情况进行了有效证明。     

不同安装倾角对双面光伏组件光伏电站发电量的影响研究

双面光伏组件采用固定支架运行方式时,在保持支架前、后排间距不变的情况下,当双面光伏组件的安装倾角不同时,组件背面接收的太阳辐射量不同,从而导致光伏电站总发电量也会不同。采用PVsyst软件模拟了不同安装倾角时双面光伏组件背面接收的太阳辐射量增益及光伏电站首年发电量情况,以便在有限的占地面积下充分利用双面光伏组件背面发电的特性,以期为今后光伏电站的设计方案比选、设计优化等工作提供依据。     

Effects of mismatch losses in photovoltaic arrays

Experimental and modeling results on the effects of mismatch losses in photovoltaic arrays are presented. Field tests conducted on each of the 192 modules are used to describe the variation in the properties of production run photovoltaic modules. Module specific estimates of a five-parameter module model are obtained by nonlinear regression. Mathematical models of four-module parallel string and series block photovoltaic array performance based on the five-parameter module model are developed and used to evaluate the variation in maximum output power and mismatch loss of arrays with random module orderings. Module maximum output power averaged 14% below the nameplate rating and exhibited a coefficient of variation of 2.1%. Mismatch losses were very small, never exceeding 0.53%. No differences between parallel string and series block arrays in array maximum output power were observed.     

Modeling the photovoltaic potential of a site

Measurements of the power produced by a photovoltaic (PV) system are important for technical as well as financial reasons, especially in large installations. The energy produced by a PV system is modeled through its nominal power, the incoming irradiance and the major energy loss mechanisms. These mechanisms involve the temperature of the cells, the response of a cell to low intensity light, the spectrum and polarization of the light, the deviation from maximum power point tracking, module mismatch and ohmic losses. The experimental quantities needed by the model are the solar irradiance at the plane of the array, the cell temperature and the nominal power of the system. In this work, we present part of the results of the theoretical calculations and their comparison with actual experimental measurements.     

基于双面组件的可调支架光伏发电系统仿真研究

以双面光伏组件和可调支架系统为基础,以青海格尔木为模拟地点,利用PVsyst光伏仿真软件,分析了不同调节次数的可调支架系统与固定支架系统在组件正面和背面辐射量、系统发电量、系统收益的差异。研究结果表明：通过调节支架改变光伏组件的角度后,组件最低点离地高度也在变化,直接影响组件正面和背面的辐射接收;光伏方阵前后间距影响土地利用率（GCR）,土地利用率降低后,背面的辐射量和系统发电量都有一定的增加;相对于固定支架双面发电系统,可调支架双面系统在不同调节次数下的组件背面全年辐射量均有一定降低,但整体的发电量得益于正面辐射的增益,最高可达4.8%左右;技术和经济比较结果显示,双面组件采用可调支架系统,每年2次的调节方式,25年生命周期内系统收益最高。文章还分析了单面发电组件和双面组件系统使用可调支架的经济性对比,在相同的调节次数下,双面组件系统的增益明显高于单面组件系统。本文的研究成果对可调支架双面组件发电系统的设计具指导作用。     

Improvement in artificial neural network-based estimation of grid connected photovoltaic power output

This paper presents a method to improve the accuracy of artificial neural network (ANN)–based estimation of photovoltaic (PV) power output by introducing two more inputs, solar zenith angle and solar azimuth angle, in addition to the most widely used environmental information, plane-of-array irradiance and module temperature. Solar zenith angle and solar azimuth angle define the solar position in the sky; hence, the loss of modeling accuracy due to impacts of solar angle-of-incidence and solar spectrum is reduced or eliminated. The observed data from two sites where local climates are significantly different is used to train and test the proposed network. The good performance of the proposed network is verified by comparing with existing ANN model, algebraic model, and polynomial regression model which use environmental information only of plane-of-array irradiance and module temperature. Our results show that the proposed ANN model greatly improves the accuracy of estimation in the long term under various weather conditions. It is also demonstrated that the improvement in estimating outdoor PV power output by adding solar zenith angle and azimuth angle as inputs is useful for other data-driven methods like support vector machine regression and Gaussian process regression.     

A power-rating model for crystalline silicon PV modules

A model for the performance of generic crystalline silicon photovoltaic (PV) modules is proposed. The model represents the output power of the module as a function of module temperature and in-plane irradiance, with a number of coefficients to be determined by fitting to measured performance data from indoor or outdoor measurements. The model has been validated using data from 3 different modules characterized through extensive measurements in outdoor conditions over several seasons. The model was then applied to indoor measurement data for 18 different PV modules to investigate the variability in modeled output from different module types. It was found that for a Central European climate the modeled output of the 18 modules varies with a standard deviation (SD) of 1.22%, but that the between-module variation is higher at low irradiance (SD of 3.8%). The variability between modules of different types is thus smaller than the uncertainty normally found in the total solar irradiation per year for a given site. We conclude that the model can therefore be used for generalized estimates of PV performance with only a relatively small impact on the overall uncertainty of such estimates resulting from different module types.     

Evaluation of the impact of solar spectrum and temperature variations on output power of silicon-based photovoltaic modules

Various types of silicon-based photovoltaic modules were installed at the same outdoor exposure site in Japan. The output parameters of the modules were measured and also incident irradiance, incident spectrum, and module temperature were recorded at the same time. A statistical analysis method has been proposed to separate the influences of spectrum variations and module temperature variations on the output performance of the modules. Moreover, with this method, the performance of polycrystalline silicon, amorphous silicon, and three-stacked amorphous silicon photovoltaic modules were analyzed.     

Bifacial photovoltaic panels field

Bifacial solar cells may produce more output energy than mono-facial solar cells because both sides of the cell, front and rear, can absorb solar radiation. This occurs when the nearby ground or other artificial surfaces are highly reflective. A gain in output power of 5–20% has been reported in the literature for special applications. The present article deals with the calculation of the annual incident irradiation on a solar field comprising of bifacial photovoltaic panels deployed in multiple rows and separated by a distance between the rows. These types of fields are designed for large scale solar electricity production. The calculation of the annual incident irradiation is compared between two types of deployments: (a) bifacial photovoltaic panels installed with an optimal tilt angle facing south, (b) bifacial photovoltaic panels installed vertically and facing the east-west direction. The study shows that bifacial photovoltaic panels installed with an optimal tilt angle may produce 32% more energy than vertical bifacial photovoltaic panels, for the same environmental conditions. On the other hand, more vertical collectors can be installed in fields with the same field dimensions.     

Experimental study on the effect of dust deposition on solar photovoltaic panels in desert environment

The accumulation of dust particles deteriorates the performance of solar cells and results in appreciable losses in the generated power due to the sun irradiance scattering effects on the surface of the solar panel. This study investigates the impact of dust accumulation on photovoltaic solar modules in Baghdad city in Iraq. For this purpose an experiment has been conducted to quantify losses caused by the accumulation of dust on the surface of three identical photovoltaic solar modules. The modules have been installed with direct exposure to weather conditions, in a well controlled experimental setup. Subsequently, measurements of dust accumulation on modules have been taken on daily, weekly and monthly basis. The dust density and size distribution of aerosol particles and fibers have been also investigated and measured by a highly sensitive aerosols measuring system. The dusted module and another similar clean module have been then exposed to constant radiation and constant temperature using a solar simulator as light source. The deposition of the dust on the surface of the photovoltaic solar modules showed a reduction in both the short circuit current (I_sc) and the output power compared to the same parameters of the clean module. The average degradation rate of the efficiencies of the solar modules exposed to dust are; 6.24%, 11.8% and 18.74% calculated for exposure periods of one day, one week and one month. The experimental results are well compared with the calculations obtained by a theoretical model recently developed by the authors.