A solar concentrator with two reflection mirrors designed by using a ray tracing method

Solar concentrators with two reflection mirrors are numerically designed by using a ray-tracing method to obtain higher concentration ratio when the concentrator tracing error is existed. The primary reflection mirror adopts paraboloidal mirror; the secondary mirror adopts hyperboloidal or ellipsoidal mirror. The optimal designed shape parameters for hyperboloidal and ellipsoidal cases are obtained, respectively. It is found that, when the concentrator tracing errors are 0°, 0.5° and 1°, the concentration ratios for hyperboloidal case are about 5837, 1954 and 1127 at f-number₁=0.22 and NA₂=0.62 and the one for ellipsoidal case are about 5860, 1993 and 1193 at f-number₁=0.25 and NA₂=0.62, respectively. Obviously, the concentrator with the ellipsoidal mirror is slightly better than the one with the hyperboloidal mirror.     

Design of a solar concentrator combining paraboloidal and hyperbolic mirrors using ray tracing method

A solar concentrator combining primary paraboloidal and secondary hyperboloidal mirrors is numerically designed by using the ray tracing method to obtain higher concentration ratio when the concentrator tracing error exists. It is found that, when the concentrator tracing errors are 0.5° or 1°, the concentration ratios are about 2027 or 1220 without the detector in the radial-direction, and the concentration ratios are about 5447 or 4701 with the detector in the radial-direction. It is shown that such method can increase the concentration solar flux by two folds when the concentrator tracing error exists. Obviously, it is an effective method to reduce the effect of concentrator tracing error even when the angle of concentrator tracing error is considered. In addition, when the angle of concentrator tracing error is small than 1°, a set of mirror shapes is suggested where the primary mirror has a f-number of 0.22 and the secondary mirror has a numerical aperture (NA) of 0.61.     

抛物碟式太阳能聚光器的聚光特性分析与设计

点聚焦碟式太阳能聚光反射器,应用光线追迹法模拟分析了存在太阳张角时,相同开口采光面积、不同形状的聚光器分别在相同焦距、相同边缘角情况下的聚光特性。考虑到太阳形状、开口采光面形状、抛物面焦距、抛物面边缘角及接收器的遮挡作用等几何因素,并结合旋转抛物面聚光器的光学特性,建立了模拟仿真的几何模型。采用光线追迹法直观地模拟了聚光接收面上的平均能流分布特性。为对聚光器的聚光特性进行定量评价,采用了面积效率因子的概念。模拟结果表明,采光面积相同时,等焦距的4种不同开口形状的聚光器具有相近的聚光能流比;等边缘角时,除圆形聚光器外的3种聚光器有较大光能损失。设计了多碟共焦聚光器,用低聚光比聚光器组合达到高倍聚光效果,并分析了聚光特性,为碟式太阳能聚光反射系统的设计和优化提供了参考。     

平板型玻璃镜反射太阳能聚光光伏系统的实验研究

提出了一种平板型玻璃镜反射太阳能聚光器,用于太阳能聚光光伏/光热利用.其结构主要由平面框架上倾斜放置粘贴或镶嵌在平直型材上的多块条形玻璃镜构成,聚光接受体为平板光伏电池或集热管.条形玻璃镜的宽度和倾斜角度随自身所处位置、聚光接受体形状尺寸和安放角度,是否考虑太阳入射光立体角影响等因素由所给公式确定.利用CCD 法测量了...     

平板型太阳能聚光器的无漏光设计

针对平板型太阳能聚光器中出现的漏光问题,提出了无漏光聚光器的设计方法.该方法结合简单的数学计算与折射定律、反射定律推导出光线在光波导板中无漏光传播的最大距离理论公式,建立了无漏光聚光比与空气隙结构张角角度、主聚光器高度和宽度之间的数学模型,利用控制变量法分析了无漏光聚光比与各参数之间的关系.运用光线追迹软件对所设计的平板型无漏光太阳能聚光器进行光线追迹模拟,结果表明:在模拟光源选择存在0.27°的发散半角的太阳光源条件下,考虑光线在透射面处的菲涅耳损失和光学材料的吸收,在无漏光范围内实际最大聚光比达到698×、857×和1 032×时的聚光效率分别为88.2%、85.3%和80.2%;超过无漏光范围后随着聚光比进一步增大聚光效率下降较平缓.     

线性菲涅耳反射聚光器聚焦光斑能流密度分布的计算

利用光线追迹的方法,考虑太阳形状、余弦损失、阴影及遮挡损失的影响,建立线性菲涅耳反射（LFR）聚光器的三维光学几何模型,给出其光斑能流密度分布的计算式,采用Matlab软件编程实现该算法。将计算结果与美国国家可再生能源实验室（NREL）开发的SolTrace软件仿真结果相对比,光斑能流密度分布曲线基本吻合,证明了该算法的正确性。为了获得更高的镜场聚光效率,对比了不同反射镜面型对LFR聚光器的影响。     

Spectrum splitting using multi-layer dielectric meta-surfaces for efficient solar energy harvesting

We designed a high-efficiency dispersive mirror based on multi-layer dielectric meta-surfaces. By replacing the secondary mirror of a dome solar concentrator with this dispersive mirror, the solar concentrator can be converted into a spectrum-splitting photovoltaic system with higher energy harvesting efficiency and potentially lower cost. The meta-surfaces are consisted of high-index contrast gratings (HCG). The structures and parameters of the dispersive mirror (i.e. stacked HCG) are optimized based on finite-difference time-domain and rigorous coupled-wave analysis method. Our numerical study shows that the dispersive mirror can direct light with different wavelengths into different angles in the entire solar spectrum, maintaining very low energy loss. Our approach will not only improve the energy harvesting efficiency, but also lower the cost by using single junction cells instead of multi-layer tandem solar cells. Moreover, this approach has the minimal disruption to the existing solar concentrator infrastructures.     

抛物面式太阳能聚能系统聚光特性模拟

结合集热器的光学特性,本文应用蒙特卡罗法对理想的槽型和碟型两种抛物面集热器在不同焦距、不同边缘角时焦面上的热流密度进行了计算,获得了焦距、边缘角和聚光比之间的关系。在考虑太阳不平行度、跟踪指向误差、镜面的反射误差条件下,对碟型抛物面太阳能聚能系统的辐射特性进行了数值模拟分析,获得了吸收器壁面热流分布以及边缘角对焦面热流分布的影响,为太阳能聚能系统的设计和安装提供参考依据。     

High-Efficiency Photovoltaic Modules with Solar Concentrators

Technical Physics - The results of research and development of solar concentrator photovoltaic modules with an area of 0.5 m2 based on Fresnel lenses with secondary solar concentrators in the form...     

聚光光伏系统的发展及未来趋势

介绍了聚光光伏系统的发展历史和研究现状。对聚光光伏系统中的主件一聚光器和光伏电池进行了详细分类，给出了它们的特点和主要参数。描述了国外一些厂家为提高光伏系统效率并降低成本而研制的太阳跟踪系统。总结出聚光光伏系统的发展趋势，主要是指高倍聚光器＋跟踪系统和低倍大角度聚光器＋分光元件＋多节电池等。最后就目前状况提出了聚光光伏系统商业化还需要解决的问题。     

Solar radiation concentrators paired with multijunction photoelectric converters in ground-based solar power plants (part I)

We have developed a method for determining parameters of radiation concentrator in solar power plants. To estimate the efficiency of concentrators in the form of Fresnel lenses in setups with three-junction photoelectric converters, the concept of the efficiency of the concentrator–photoelectric converter pair has been introduced. We have proposed a method for calculating the refracting profile of concentrators taking into account the dispersion relation for the refractive index and its variations with temperature for the material of the refracting profile of the concentrator (Wacker RT604 silicone compound). The results of calculation make it possible to achieve the maximal efficiency of the concentrator–photoelectric converter pair in the presence of chromatic aberrations in the optical system of solar radiation concentration.     

Application of millimeter-sized polymer cylindrical lens array concentrators in solar cells

A unique method is proposed to encapsulate solar cells and improve their power conversion efficiency by using a millimeter-sized cylindrical lens array concentrator. Millimeter-sized epoxy resin polymer(ERP) cylindrical lens array concentrators are fabricated by the soft imprint technique based on polydimethylsiloxane stamps. The photovoltaic measurements show that millimeter-sized ERP cylindrical lens array concentrators can considerably improve the power conversion efficiency of silicon solar cells. The validity of the proposed method is proved by the coupled optical and electrical simulations. The designed solar cell devices with the advantages of high-efficiency and convenient cleaning are very useful in practical applications.     

An Investigation of the Influence of Secondary Optical Elements on the Output Parameters of Photovoltaic Modules

Technical Physics - Secondary optical concentrators (focons) designed to operate in a solar concentrator photovoltaic module with Fresnel lenses have been developed and investigated. Both...     

一种离轴凸双曲面单修加工及检测方法的研究

离轴凸双曲面的加工和检测是非球面加工检测中的一个比较困难的问题.结合一块口径φ230mm、离轴量226mm的凸双曲面镜,提出了离轴凸双曲面镜单修加工以及采用离轴Hindle球检测偏转角度的离轴凸双曲面镜这一方案.给出了单修加工工艺,并解决了检测光路的搭建难点.加工完成的离轴凸双曲面的面形精度RMS优于λ/50(λ=63...     

大型双曲面次镜面形检测技术现状及发展趋势

随着以双曲面为次镜的两镜光学系统在天文和空间光学等领域的应用日趋广泛,双曲面次镜的口径和相对口径越来越大,由此对双曲面次镜的面形检测技术提出了很高的要求。本文基于国外有代表性的双曲面次镜参数分析了其基本特征和发展趋势,重点介绍了国外大型双曲面次镜的面形检测技术,并对其中的关键技术进行了分析。同时,概述了国内双曲面次镜检测技术现状。最后,总结和展望了大型双曲面次镜面形检测技术发展趋势。提出今后一段时间内,高均匀性的光学透射材料,高精度、大口径的辅助元件以及基于子孔径拼接的检测方法和数据处理方法是该领域的研究重点。     

Design of an off-axis XR photovoltaic concentrator with SMS method

We present a novel off-axis XR concentrator design that enables a high efficiency energy collection while avoiding the shadowing problem encountered in the designs of symmetry XR type concentrator. Combining with a 1 cm² multi-junction solar cell, the off-axis XR concentrator is able to achieve high optical efficiency of the photovoltaic system. The concentrator design is performed based on the non-imaging optic principle, with one reflective mirror (X) and one refractive lens (R). Both surfaces of the reflective and refractive element are of freeform shapes and fitted as freeform expression in the design analysis. The concentrator has concentration ratio greater than 500× and acceptance angle greater than 2°. A square homogenizing irradiance distribution on the cell is achieved with the help of a suitable rob. The tolerance of the system is analyzed. The results show that the high concentration ratio and greater acceptance angle relax all optical and mechanical tolerances reduce the production and operation cost.     

大口径平面镜的计算机辅助瑞奇-康芒检验

 在瑞奇-康芒检测中,被检平面本身所固有的像散和大曲率在被检系统波像差数据中都表现为像散。由于被检平面处于发散光路中,这就使得平面面形与系统波像差之间的关系(即影响函数)变得十分复杂,推导起来十分困难,只能进行定性或半定量检测。文中介绍了如何通过计算机光线追迹模拟瑞奇-康芒检验,在两个瑞奇角下得到两组影响函数,以此建立过定方程组,由干涉仪检测得到的两个不同瑞奇角下的系统波像差,通过最小二乘法解过定方程组,拟合得到被检平面镜的面形误差;实现了大口径平面镜的定量检测,并以平面镜直接检验的面形误差作为对比,检验结果的一致验证了该方法的准确性与可行性。     

复合抛物面聚光器作为可见光通信光学天线的设计研究与性能分析

针对室内可见光通信的特点, 选择复合抛物面聚光器作为可见光通信系统光学天线, 介绍了复合抛物面聚光器的几何结构和光学特性, 利用光学仿真软件 TracePro对复合抛物面聚光器进行了设计、建模与仿真. 通过对不同光源条件下复合抛物面聚光器聚光特性的仿真发现: 在光源为朗伯辐射模型时复合抛物面聚光器的聚光性能更好, 且视场角越小增益越高; 但接收端与光源的相对位置对小视场复合抛物面聚光器的实际增益有明显影响, 在仿真条件下, 视场角为10°的复合抛物面聚光器实际增益为22.88, 比理论值降低了31%. 在此基础上, 在一个5 m×5 m×3 m的房间中对采用复合抛物面聚光器为光学天线的室内可见光通信系统进行了建模, 分别得到了直射链路和非直射链路下房间内各个位置的光功率分布. 仿真结果表明, 采用一个视场角为60°的复合抛物面聚光器为光学天线, 两种链路下平均接收功率分别提高了4.29 dBm和4.77 dBm, 非直射链路比直射链路的平均接收功率提高了11.2%.     

Optical efficiency of solar concentrators by a reverse optical path method

A method for the optical characterization of a solar concentrator, based on the reverse illumination by a Lambertian source and measurement of intensity of light projected on a far screen, has been developed. It is shown that the projected light intensity is simply correlated to the angle-resolved efficiency of a concentrator, conventionally obtained by a direct illumination procedure. The method has been applied by simulating simple reflective nonimaging and Fresnel lens concentrators.     

极大口径光学望远镜凸非球面副镜的补偿检测法研究

提出了一种检测大口径、快焦比凸双曲面反射镜的补偿检验方法,补偿系统由一组小透镜和一块大口径反射标准镜组成,标准镜的口径约为被检验镜的1.8倍,该方法为极大口径光学望远镜凸非球面副镜的检验提供了一种有效的解决方案。以美国30 m望远镜（TMT）3.1 m,F/1的凸双曲面副镜为例,进行了补偿光路的设计优化。设计结果表明,该方法可以直接检测到直径达3.1 m的大口径、快焦比凸双曲面副镜的整个表面质量,补偿系统像差被校正得很好,PV值约为/100,弥散斑直径在衍射极限范围内。