应用于聚光光伏模组的全反射式二次聚光器的设计与性能分析

当前聚光光伏系统存在很多问题,比如跟踪器的跟踪精度偏低、聚焦光斑强度分布不均匀、聚焦光斑的形状跟太阳电池不匹配等,二次聚光器可以解决这些问题,从而提高高倍聚光光伏系统的光电转换效率.对高倍聚光光伏系统中的菲涅耳透镜和二次聚光器的聚光原理进行了简要分析,重点对全反射式二次聚光器进行了二维聚光的理论分析,并配合非成像光学的...     

离子束刻蚀法制作菲涅耳透镜

由于衍射光学元件独特色的色散特性及体积小、重量轻可进行复制等优点,它在国防、生产及科研等领域的作用越来越重要,应用于光学成像系统,不仅能改善系统成像质量,而且能实现系统的轻量化、小型化,增加系统设计的自由度。使用离子束刻蚀法制作的16阶菲涅耳透镜应用于折衍混合CCD相机;测量菲涅耳透镜的衍射效率并分析了影响衍射效率的因素。     

分布式焦点法线聚焦菲涅耳聚光器设计及性能分析

在聚光型光伏系统中,聚光光斑的幅照度不均匀性会降低光伏电池的光电转换效率:并且造成光斑局部点的能量过高,灼伤光伏电池.根据非成像光学理论,介绍了一种基于分布式焦点法设计线聚焦菲涅耳聚光器的方法,并与传统采用共焦法设计的线聚焦菲涅耳聚光器进行了对比分析.结果表明:在保证能量聚光比以及最大能量透过率不变的情况下,使用分布式焦点法设计的菲涅耳聚光器可使聚光光斑的辐照度均匀性得到很大改善,有利于提高光伏电池的光电转换效率,延长光伏电池的使用寿命.     

太阳能采集用1000mm口径菲涅耳透镜设计

针对太阳能利用率较低、光伏发电成本过高的问题,从聚光器的角度出发,采用菲涅耳透镜对太阳光进行聚焦.在分析菲涅耳透镜结构的基础上,提出了透镜主要性能指标,设计了一个满足要求的1 000 mm口径透镜,对聚光时透镜位置的放置进行了讨论.该设计具有一定的通用性,可以适用于其他大口径的菲涅耳透镜设计,对于促进太阳能采集发展具有重要意义.     

薄膜沉积法制作菲涅耳透镜

衍射光学元件在国防、生产及科研等领域起着为越重要的作用。衍射光学元件的制作技术主要包括激光或电子束直写、反应离子刻蚀、离子束铣及薄膜沉积。薄膜沉积法具有精确控制台阶高度及台阶表面较光滑的优点。使用薄膜沉积法制作１６阶菲涅耳透镜,用它代替常规的光学透镜可实现系统的轻量化、小型化、增加系统设计的自由度,屯菲涅耳透镜的衍射效率并分析产生误差的原因。     

菲涅耳微透镜列阵衍射效率的测试

提出了一种测试菲涅耳微透镜列阵衍射效率的有效方法，采用Ｈｅ－Ｎｅ激光器作为测试光源，利用计算机辅助测试构成了一个衍射效率测试光路系统，对测试原理进行了分析，该方法具有简便易行的特点，适于测试具有微小单元尺寸、周期密排的二元微光学元件的衍射效率。     

一种环面焦斑菲涅耳聚光器的设计与分析

在聚光光伏系统中,聚光光斑辐照度的不均匀性会降低光伏系统的光电转换效率,且会在光伏电池表面形成热斑效应,灼伤光伏电池。基于多焦点方法,设计了一种环形焦斑菲涅耳太阳能聚光镜,每环小透镜在焦平面上具有一个环面焦斑,且环面焦斑在接受面上均匀依次排列,实现均匀聚光。以口径400mm,具有200环,焦斑半径20mm,F数为0.8的圆状环面焦斑菲涅耳聚光器为实例,用TracePro模拟平行太阳光垂直照射下时的照度图,得到其理想光学效率为86.77%,光能均匀度为0.8,表明环状焦斑菲涅耳聚光器具有较高的光能利用率和照明均匀性。分析了焦斑均匀性与聚光器F数的关系,当F数一定时,焦斑均匀性随着聚光器口径的增大而逐渐降低。     

大口径菲涅耳透镜远距离宽光谱聚光系统设计

针对使用光纤光谱仪探测远距离宽光谱弱信号的应用需求,基于成像光学与非成像光学的混合设计方法,设计了大口径菲涅耳透镜聚光系统。系统由直径为1.1 m的菲涅耳透镜、匀光棒、全反射准直器和中继透镜组组成,接收端为直径为2 mm、数值孔径为0.22的光纤束。大口径菲涅耳透镜具有质轻体小的优点,解决了传统大口径透镜体积大质量大的问题。由匀光棒和全反射准直器组成的非成像光学元件后组可减小由菲涅耳透镜口径增大引起的球差和宽光谱色差,使光信号能量分布更加均匀且出射角度减小;中继透镜组进一步控制光束发散角和光斑尺寸,使光信号在光纤束端面高效率耦合,提高系统的光能利用率。仿真和实验结果均表明,所设计的后组系统能够减小像差影响,有效控制光束发散角度和光斑尺寸,提高光能利用率,满足光纤光谱仪对远距离宽光谱弱信号进行光谱探测的需要。     

线性菲涅尔式聚光集热系统研究进展

相比槽式聚光集热系统,线性菲涅尔式聚光集热系统光学效率较低,但具有成本优势。为了提高其光学性能和热性能,减少热损失,国内外学者进行了广泛研究。在总结线性菲涅尔式聚光集热系统主反射镜、二次反射接收器和镜场的优化设计,以及系统热性能等国内外已有研究成果的基础上,重点阐述了由阴影与遮挡、末端损失、跟踪误差、积尘、主反射镜镜场几何结构引起的光学损失及改进措施最新研究进展,对主流的几种二次反射接收器进行了对比分析,表明复合抛物面二次反射接收器（Composite Parabolic Concentrator, CPC）最实用。同时对吸热管和工作介质之间的强化传热、采用CPC的线性菲涅尔式聚光器热损失进行了归纳总结,分析了存在的问题及解决方法,指出了线性菲涅尔式聚光集热系统的未来发展方向和改进措施。     

分布式光伏并网运行仿真分析系统设计

针对分布式光伏并网配电网运行研究的问题,文章设计了一套分布式光伏并网运行仿真分析系统,由仿真平台和数据采集器构成。仿真平台搭建一个基于通用的IEEE30节点配电网模型及其参数的模拟电网,分布式光伏可接入设定节点。基于仿真系统,实现分布式光伏发电系统的监测与控制、电网的实时运行仿真、系统潮流计算、参数修改设定、灵敏度分析、数据保存与导出、用户管理等功能,研究分布式光伏并网运行情况及规律。文章为分布式光伏并网运行研究提供一种新的研究思路和实践探索。     

Learning curve analysis of concentrated photovoltaic systems

Price declines and volume growth of concentrated photovoltaic (CPV) systems are analysed using the learning curve methodology and compared with other forms of solar electricity generation. Logarithmic regression analysis determines a learning rate of 18% for CPV systems with 90% confidence of that rate being between 14 and 22%, which is higher than the learning rates of other solar generation systems (11% for CSP and 12 to 14% for PV). Current CPV system prices are competitive with PV and CSP, which, when combined with the higher learning rate, indicates that CPV is likely to further improve its marketability. A target price of 1 $/W in 2020 could be achieved with a compound growth rate of 67% for the total deployed volume between 2014 and 2020, which would realize a cumulative deployed volume of 7900 MW. Other projections of deployment volumes from commercial sources are converted using the learning rate into future price scenarios, resulting in predicted prices in the range of 1.1 to 1.3 $/W in 2020. © 2014 The Authors. Progress in Photovoltaics: Research and Applications published by John Wiley & Sons Ltd.     

Modeling a grid‐connected concentrator photovoltaic system

A six‐parameter formula is proposed for describing the hourly alternating current performance of a grid‐connected, passively cooled concentrator photovoltaic (CPV) system. These system parameters all have physical meanings, and techniques are described for deriving their numerical values. The predictions of the model are compared with the measured output of a Soitec CPV system at Sede Boqer and found to be accurate to approximately ± 5% at all times of the year. The model should also be valid for systems of similar construction operated in different climates from the system studied here, and also for passively cooled CPV systems of different designs provided that suitable numerical values are determined for their system parameters. Another possible use of the model is as a guide for tailoring CPV cell architecture to the particular spectral conditions of the locations in which they will operate. Attention is drawn to the fact that the numerical values of some of the system parameters are found to depend upon the time binning employed for the data. An explanation is given for this phenomenon, which is also found to occur for non‐concentrating photovoltaic panels. Copyright © 2014 John Wiley & Sons, Ltd.     

Durability of polymeric encapsulation materials in a PMMA/glass concentrator photovoltaic system

The durability of polymeric encapsulation materials was examined using outdoor exposure at the nominal geometric concentration of 500 suns. The results for 36‐month cumulative field deployment are presented for materials including: poly(ethylene‐co‐vinyl acetate), (EVA); polyvinyl butyral (PVB); ionomer; polyethylene/polyoctene copolymer (PO); thermoplastic polyurethane (TPU); poly(dimethylsiloxane) (PDMS); poly(diphenyl dimethyl siloxane) (PDPDMS); and poly(phenyl‐methyl siloxane) (PPMS). Measurements of the field conditions including ambient temperature and ultraviolet (UV) dose were recorded at the test site during the experiment. Measurements for the experiment included optical transmittance (with subsequent analysis of solar‐weighted transmittance, UV cut‐off wavelength, and yellowness index), mass, visual photography, photoelastic imaging, and fluorescence spectroscopy. While the results to date for EVA are presented and discussed, examination here focuses more on the siloxane materials. A specimen recently observed to fail by thermal decomposition is discussed in terms of the implementation of the experiment as well as its fluorescence signature, which was observed to become more pronounced with age. Modulated thermogravimetry (allowing determination of the activation energy of thermal decomposition) was performed on a subset of the siloxanes to quantify the propensity for decomposition at elevated temperatures. Supplemental, Pt‐catalyst‐ and primer‐solutions as well as peroxide‐cured PDMS specimens were examined to assess the source of the luminescence. The results of the study including the change in optical transmittance, observed failure modes, and subsequent analyses of the failure modes are described in the conclusions. Copyright © 2016 John Wiley & Sons, Ltd.     

Development of concentrator modules with dome‐shaped Fresnel lenses and triple‐junction concentrator cells

The status of the development of a new concentrator module in Japan is discussed based on three arguments, performance, reliability and cost. We have achieved a 26·6% peak uncorrected efficiency from a 7056 cm² 400 × module with 36 solar cells connected in series, measured in house. The peak uncorrected efficiencies of the same type of the module with 6 solar cells connected in series and 1176 cm² area measured by Fraunhofer ISE and NREL are reported as 27·4% and 24·8% respectively. The peak uncorrected efficiency for a 550× and 5445 cm² module with 20 solar cells connected in series was 28·9% in house. The temperature‐corrected efficiency of the 550 × module under optimal solar irradiation condition was 31·5 ± 1·7%. In terms of performance, the annual power generation is discussed based on a side‐by‐side evaluation against a 14% commercial multicrystalline silicon module. For reliability, some new degradation modes inherent to high concentration III‐V solar cell system are discussed and a 20‐year lifetime under concentrated flux exposure proven. The fail‐safe issues concerning the concentrated sunlight are also discussed. Moreover, the overall scenario for the reduction of material cost is discussed. Copyright © 2005 John Wiley & Sons, Ltd.     

三相光伏发电并网系统的建模与仿真

为了真实地模拟光伏发电并网系统,针对光伏发电并网的最大功率点追踪,给出了基于电导增量法的控制方法,提高了光伏电池阵列的工作效率。利用Boost电路实现MPPT控制,以SVPWM变换形成PWM波,在此基础上分别从光伏发电并网系统的各重要组成部分出发,建立了一套两级式三相光伏并网发电系统模型。最后,通过仿真对所搭建模型的动态性能进行验证。仿真结果表明,该模型能够真实地反映三相光伏发电并网系统的实际运行特性,具有较好的动态性能。