光伏电池阵列模拟器研究

文章分析了光伏电池阵列的输出电压电流特性,根据光伏阵列实际电压电流参数进行了仿真,给出了输出电压电流特性的仿真曲线,利用多项式对特性曲线进行了分段拟合,在此基础上利用BUCK电路设计了光伏电池阵列模拟器,采用输出电流反馈PI调节提高了系统的动态性能以及稳态精度。通过仿真和实验验证了设计的合理性。     

聚光光伏技术及研究进展

<正>聚光光伏技术是指利用光学元件将太阳光汇聚后,通过高转化效率的光伏电池(GaAs基)直接转换为电能的技术,被认为是太阳能发电未来发展趋势的第三代技术,即聚光光伏(CPV)。1.聚光光伏技术概述GaAs基太阳能电池可分为单结和多结叠层式太阳能电池两类。GaAs、Ge单结太阳电池理论效率27%,实验室效率达到     

硅纳米线阵列光伏电池及其广角光伏转换

采用金属援助刻蚀和溶液填充的方法,构筑了原理型Si/导电聚合物(聚3,4-乙撑二氧噻吩:聚苯乙烯磺酸盐,PEDOT:PSS)核壳纳米线阵列光伏电池。电池的光伏转换效率不依赖于入射光强,达到了6.8%。改变入射光角度,表征了电池的广角光伏转换性能。入射角在45°范围内的有效光电转换效率相对于正入射的光伏转换效率仅降低12%。实验结果表明,纳米线阵列结构的光伏电池有益于广角太阳能转换。     

聚光跟踪式光伏技术面世

太阳能是最丰富的可再生能源，但其发电的高成本一直是大规模开发利用的障碍。能否经济高效地利用太阳能的关键在于太阳聚光和跟踪水平的优劣。目前，世界各国都将提高太阳能发电效率和降低太阳能发电成本，作为科学研究以及产业化的前沿工作。中国科技大学太阳能研究院陈应天教授及其团队与安徽应天新能源有限公司，经过2年多合作研制的数倍聚光光伏发电系统取得了太阳能光伏发电的技术突破。即使在目前百千瓦级的较小电站规模下，     

光伏电池阵列、MEMS模仿荷叶自清洁功能

自然界中，荷叶具有最好的不粘水表面。佐治亚工学院的研究人员正在模仿这种疏水功能，以研制更可靠的电力输送系统，维持光伏电池阵列的高效率，使微机电系统（MEMS）结构不受水影响，改进具有生物活性的表面阻止生物细胞粘到医疗器件上。     

光伏阵列在局部阴影下的建模与特性分析

光伏阵列在阴影影响下输出特性将发生变化,传统的光伏阵列模型不再适用。为了研究光伏阵列在阴影影响下的输出特性,在单个光伏电池四参数工程模型的基础上,推导出适用于在不同光照下2个光伏电池串联的输出模型。在Matlab中对其仿真并与实验结果做比较,验证推导模型的准确性。把该模型推广到多个光伏电池串并联的光伏阵列中,引入遮光率,在Matlab中对光伏阵列在不同遮光率下进行仿真,分析其仿真结果,总结出光伏阵列在局部阴影影响下输出特性的变化规律。     

基于TMS320F28335的光伏电池模拟器设计

提出了一种基于DSP控制的数字式光伏电池模拟器的设计方法,这种模拟器可在太阳能电池阵列容量一定时,通过高性能控制芯片TMS320F28335来完成对系统数据的采集、分析、处理和实时控制,实验表明,该模拟器可以完整复现太阳能电池阵列的Ⅰ—Ⅴ特性。     

TiO_2纳米管阵列对染料敏化太阳能电池性能的影响

通过恒压阳极氧化法在Ti箔表面制备了结构规整的TiO2纳米管阵列,研究了氧化时间和退火温度对纳米管阵列的尺寸和晶体结构的影响。用制得的纳米管阵列电极组装了染料敏化太阳能电池(DSSC),研究了纳米管长度、退火温度和电极面积对DSSC光电性能的影响。结果表明,纳米管管径和壁厚均与氧化时间无关,而纳米管长度则随着氧化时间延长而增加。在450℃及更低温度退火时,纳米管中只出现锐钛矿相;而在500℃退火时,纳米管中则又出现了金红石相。由厚度为27μm、退火温度为450℃的纳米管阵列电极组装成的DSCC具有最佳的光电转化性能。DSCC的光电转化效率随电极面积的增加而降低。     

基于遗传算法的太阳能飞艇光伏阵列优化研究

太阳能飞艇依赖于光伏阵列提供能量,但曲面面形引起的非均匀光照会造成光伏阵列的能量损失。文章将遗传算法引入光伏阵列优化研究,通过优化光伏阵列拓扑结构,降低模块间的失配现象,从而达到增大输出功率的目的。首先基于光伏电池的单二极管模型,给出光伏阵列的仿真方法。其次提出基于遗传算法的光伏阵列拓扑结构的优化方法,采用序列编码方式,将光伏阵列拓扑结构转化为染色体编码,通过染色体基因位的交叉变异实现光伏阵列拓扑结构的优化。以某太阳能飞艇为例进行仿真验证,优化后光伏阵列平均输出功率增大2.32%,仿真结果表明所提方法能够有效提高太阳能飞艇光伏阵列的输出功率。     

基于TMS320F28335的大功率数字式光伏电池阵列模拟器设计

近年来光伏发电技术迅速发展,世界各国都将其视为未来的主要新能源,期待它能解决全球性的能源危机。光伏发电技术研究的一项主要内容是光伏电池阵列。文中针对光伏电池阵列研究的诸多不便设计了一种基于TMS320F28335DSP控制的大功率数字式光伏电池阵列模拟器,介绍了整个模拟器系统的设计方法,并通过实验验证了该系统的可行性,在实验室实现了最大18 kW的输出功率,所制样机能够代替光伏电池阵列。     

Performance analysis of solar cell arrays in concentrating light intensity

tage in concentrating light intensity. The output power has a -20 W/V coefficient and so cooling fluid must be used. Both heat energy and electrical power are then obtained with a solar trough concentrating photovoltaic/thermal system.     

Concentrator multijunction solar cell characteristics under variable intensity and temperature

The performance of multijunction solar cells has been measured over a range of temperatures and illumination intensities. Temperature coefficients have been extracted for three‐junction cell designs that are in production and under development. A simple diode model is applied to the three‐junction performance as a means to predict performance under operating conditions outside the test range. These data may be useful in guiding the future optimization of concentrator solar cells and systems. Copyright © 2008 John Wiley & Sons, Ltd.     

透镜与电池间距对聚光光伏系统特性影响的实验研究

实验研究了聚光太阳电池上光照强度、短路电流、开路电压、电池温度和光电转换效率随菲涅耳透镜与电池的距离变化关系。结果表明,聚光条件下,太阳电池性能的提高主要源于短路电流的变化,而不是开路电压;聚光后,太阳电池与透镜距离为焦长时,输出功率可以达到最大值;太阳电池的最大单位光强转换效率需要把太阳电池放到透镜焦点前。本文研究结果对于聚光光伏系统的研制具有指导意义。     

Modeling of concentrating photovoltaic and thermal systems

An energy balance model for concentrating photovoltaic and thermal (CPVT) systems is presented. In the model, the CPVT system and its environment are represented using a set of input parameters. The main outputs of the model are the system's electrical and thermal efficiencies. The model accounts for optical losses. Thermal losses are derived from a thermal network model of the hybrid receiver. The solar cell performance is modeled as a function of the temperature and the irradiance. The robustness of the model is demonstrated by a sensitivity analysis of all input parameters. The influence of the operating temperature on the electrical and thermal performances and the overall efficiency of the CPVT system are discussed. The limiting cases of maximum electrical and thermal power outputs are presented. Further, the influence of the concentration ratio on the electrical and thermal performance and on the partitioning of these two power outputs is analyzed in detail. It is shown that high concentration reduces the thermal losses considerably and increases the electrical efficiency. At concentration ratios above 300, the system operates with an overall efficiency of 75% at temperatures up to 160 °C. Copyright © 2012 John Wiley & Sons, Ltd.     

Modeling of a concentrating photovoltaic system for optimum land use

Concentrating photovoltaic solar power plants using dual‐axis trackers are in increasing demand. In a utility‐scale photovoltaic system, both capacity factor and ground coverage ratio are widely used to characterize systems in view of the land use efficiency. Current system modeling approaches lack accurate location‐specific direct normal irradiance (DNI), miss a reliable electrical model for power optimization and conversion and are inadequate for optimizing the tracker array configuration. In this paper, a comprehensive modeling of a concentrating photovoltaic system is introduced. First, a more accurate estimation of hourly DNI is obtained by considering location‐dependent DNI and air mass changes according to the sun's elevation. Second, mismatch effects of modules are factored in. Third, various power optimization and conversion levels are taken into account for optimization with self‐shading in each module. The tracker array configuration has been optimized to maximize energy harvest by getting a maximum capacity factor for a given ground coverage ratio. Copyright © 2011 John Wiley & Sons, Ltd.     

Novel multijunction solar cell design for low cost,high concentration systems

In the quest to reduce the levelized cost of energy, recent concentrated photovoltaics innovations have striven to increase the solar cell conversion efficiency. Another approach aims at concentrating more light on the solar cell in order to reduce its share of the energy cost. We propose new cell structures that are tailored for high conversion efficiency at solar concentration exceeding 1000 suns, with a minimum amount of heat generated. These designs are composed of multiple junctions (3, 4, and 5) of materials lattice matched to gallium arsenide (GaAs) with bandgaps at or above that of GaAs. Simulations that include thermal effects and electrical resistance effects are used to predict the performances of the proposed designs under high concentrations. A relative cost analysis shows a reduction in electricity cost when using these designs compared with the state of the art triple‐junction solar cell. Further cost reduction schemes using these proposed designs are discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

A review of optical and thermal transfer fluids used for optical adaptation or beam‐splitting in concentrating solar systems

There are a wide variety of solar thermal, photovoltaic, and hybrid photovoltaic–thermal concentrator systems and concepts that use liquids for optical adaptation and heat transfer. Depending on the functional purpose of the fluid: heat transfer, optical adaptation, spectral filtering, or a combination of these applications, different fluid properties are required. This review studies actively cooled solar concentrators and their associated requirements for liquids. The most suitable candidate fluids available in the market are assessed according to their properties and applications, with a special emphasis on fluid toxicity and long‐term performance. Copyright © 2012 John Wiley & Sons, Ltd.     

光强和温度对多结太阳电池的影响研究

基于模拟太阳光源的方法,在室内研究了在不同光照强度、不同工作温度下GaAs多结太阳电池的输出特性.通过实验得出:随着光源辐照强度的增加,太阳电池的特性参数:短路电流Isc线性增加,开路电压Voc对数增加,最大输出功率P线性增加,光电转换效率η随聚光比增加到一定程度后减小.对比分析了光强和温度对电池输出特性的影响,数据结...     

Series resistance characterization of industrial silicon solar cells with screen‐printed contacts using hotmelt paste

This work presents the results of a detailed series resistance characterization of silicon solar cells with screen‐printed front contacts using hotmelt silver paste. Applying the hotmelt technology energy conversion efficiencies up to 18·0% on monocrystalline wafers with a size of 12·5 cm × 12·5 cm have been achieved, an increase of 0·3% absolute compared to cells with conventional screen‐printed contacts. This is mainly due to the reduction in the finger resistance to values as low as 14 Ω/m, which reduces the series resistance of the solar cell significantly. To retrieve the lumped series resistance as accurately as possible under the operating condition, different determination methods have been analyzed. Methods under consideration were fitting of the two‐diode equation function to a dark IV‐curve, integration of the area A under an IV‐curve, comparison of a j_sc–V_oc with a one‐sun IV‐curve, comparison of the j_sc and V_oc points of a shaded curve with the one‐sun IV‐curve as well as comparison of a dark IV‐curve with a one‐sun IV‐curve, and comparison of IV‐curves measured at different light intensities. The performed investigations have shown that the latter four methods all resulted in reliable series resistance values. Copyright © 2007 John Wiley & Sons, Ltd.     

A mechanism of solar cell degradation in high intensity,high temperature space missions

The behavior of standard space photovoltaic assemblies in a high intensity, high temperature environment (HIHT) is addressed. Experimentally, an HIHT environment, typical for missions to the inner planets of the solar system such as Mercury, characterized by temperatures of 500K and 11 solar constant irradiance in the ultraviolet region below 400 nm, was simulated in a vacuum. Independently of the triple junction cell technology used, module degradation up to 20% in power was observed during several hundred hours of test. Electroluminescence analysis identified discrete top cell shunts close to the cell edge, in particular around the frontside contact pads. Cross‐sectional transmission electron microscopy performed on several degraded cells revealed an etched contact pad metallization/cap layer interface and more importantly, several 100‐nm large, oriented Cu₃P inclusions at the shunted locations. A chemical degradation mechanism is proposed. Short wavelength ultraviolet light interacting with polysiloxanes used as module encapsulant produces hydrogen and methyl radicals. With these building blocks, an organic acid can be formed on external reaction surfaces such as the Ag busbars that simultaneously serve as a source of oxygen. Cu traces present in the Ag segregate to the surface and are transported by this acid to the contact pad of the cell in the liquid phase. An adapted cell design was developed to prevent this degradation mechanism believed to be of relevance for all HIHT space environments. A several hundred micrometer‐wide rim composed of the outermost cell area is electrically separated from the inner cell area and provides a barrier against environmental attack. None of the photovoltaic assemblies featuring this mesa cell design showed any fill factor‐induced power degradation any more. Copyright © 2011 John Wiley & Sons, Ltd.