基于棱镜二次聚光的高倍聚光模组聚光特性与三结电池光谱响应匹配与优化

目前Ⅲ-Ⅴ多结高倍聚光(HCPV)太阳电池实验室效率记录已高达46%,而相对应的模组效率与之相差仍较大,其中由于模组中聚光非理想性引起的损失就高达20%.本文通过建立光学模型和非均匀光照的三维电池电路网络模型,以Ⅲ-Ⅴ族三结电池为例,研究了菲涅耳透镜一次聚光、棱镜二次聚光的HCPV模组的聚光特性和光电特性.结果发现.由于光线非平行入射和-菲涅耳透镜的色散现象,使得沿光轴方向短、中、长波段聚光发散及聚光不均匀,从而造成了三结电池的上、中、下各子电池光谱响应失配损失,模组光电转换性能下降;进一步,通过采用棱镜二次聚光,能较好地改善聚光和温度均匀性;通过对光轴方向上短、中、长波段的聚光特性与三结电池光谱响应匹配优化,使得模组输出功率提高10%以上.模拟结果己得到实验验证.     

三结太阳电池在非均匀光照下光斑强度和覆盖比率的优化研究

高倍聚光光伏组件通常采用光电转化效率较高的三结太阳电池.由于聚光器件的非理想性,电池承受的光照分布通常是高度非均匀的,在光伏组件中可通过适当增大光斑与电池面积的比率来降低光照非均匀性对电池电学性能的影响.通过对某一特定三结电池进行电路网络建模计算,分析光斑的强度分布和照射面积对电池的影响,并对比了四种设计方案(均匀光照、非均匀光照、电池效率最大、组件效率最大)下的光斑强度、光斑大小、电池效率以及电池温度分布.对比分析结果表明,组件达到效率最大时的电池效率并不是电池在标准测试条件下的最大效率,而使电池工作在效率最大值的设计方案中组件效率最低.组件效率最大方案中使用的聚光器透镜面积较小,因此该方案将导致组件成本增大.电池效率最大方案中使用的聚光器透镜面积较大并且电池温度最低,故该方案组件成本较低且可靠性较高.这表明在实际组件设计中应充分考虑对发电量的实际需求,选择合适的几何聚光倍数和光斑覆盖电池的比率.     

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.     

高倍聚光光伏模组中三结太阳电池沿光轴方向光电性能与优化

目前,在高倍聚光光伏模组设计中,由于对菲涅耳透镜聚光后各波段的光强分布及其非均匀特性缺乏研究和认识,通常认为在菲涅耳透镜的聚光焦平面处多结太阳电池输出功率最大.本文通过光线跟踪模拟的方法,计算并分析菲涅耳透镜聚光下不同波段的光照能量分布和非均匀特性.同时,结合三结太阳电池电路网络模型,研究在高倍聚光光伏模组中,沿光轴方向不同位置处三结太阳电池的发电性能.结果表明:模组输出功率最高位置在焦平面沿光轴方向上下两侧的位置,优化后模组输出功率比常规设计提高20%以上.该模拟结果得到了实验结果的验证.     

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...     

High concentration and homogenized Fresnel lens without secondary optics element

In this paper, we design a single concentrator to homogenize and concentrate the solar energy. The proposed concentrator only consisted of an array of refraction prisms. In order to homogenize the irradiance, all pitches of the Fresnel concentrator focus on the different position of the receiver. Finally, the Fresnel lens that achieves the uniformity of U is 14.6. An acceptance angle of 0.305° is achieved without using additional secondary optics. Full Width at Half Maximum (FWHM) of illumination distribution is 1.4 mm.     

Design of hemispherical cavities for LED-based illumination devices

We present the design procedure for an illumination system based on the association of several emitting diodes in optical cavities with a hemispherical shape. The main purpose of this illumination system is to provide high amounts of monochromatic light over small areas, thus making it adequate for testing radiation-sensing devices. A detailed methodology for the optimization of the optical system, by taking into account both the electro-optical properties of the emitting diodes and the geometry of the cavity, is described. The irradiance on the working plane is increased by using a pulsed current operation mode at low duty cycles for light emitting diodes. The performance of two illumination devices designed with this methodology has been tested through the measurement of some concentrator GaAs solar cells. Current densities up to 5 A/cm² have been obtained in these cells with a cavity based on infrared emitting diodes. PACS 42.15.Eq; 85.60.Bt; 85.60.Jb     

矩形复合抛物面空间双向照明节能多功能反光杯设计

提出了充分利用灯具空间,具有单体双向多功能的光学设计新理念。结合LED与CPC,根据光学扩展量守恒,借助光路可逆原理与边缘光线原理,构造矩形复合抛物面。根据我国最新的《读写作业台灯性能要求》GB/T 9473-2017,以出光口半宽、台灯辐照高度、截短后杯体长度比为3个因素,设计正交实验,确定台灯矩形复合抛物面最适合参数为:出光口半宽50 mm、最大进光半角47.73°、截取杯体长度36 mm。在照明方面,该矩形复合抛物面能够满足关于A、AA级的照度和照度均匀度要求;在弱光聚集方面,其太阳能芯片位置的照度是不经聚光情况的1.25倍;在聚光模式下,太阳能芯片的光伏转化效率是非聚光模式下的1.66倍。这是对当前市面上非聚光模式收集太阳能方式的补充。     

Quaternary n-Al0.08In0.08Ga0.84N/p-Si-based solar cell

Quaternary n-type Al_0.08In_0.08Ga_0.84N grown on p-Si using molecular beam epitaxy technique was fabricated as a pn-junction and an anti-reflection coating (ARC) of solar cells. The structural properties and surface morphology of the solar cells were investigated using scanning electron and atomic force microscopy. Optical reflectance was obtained using an optical reflectometery system (Filmetric F20-VIS). Current–voltage characteristics were examined under 100 mW cm^?2 illumination conditions. Quaternary n-type Al_0.08In_0.08Ga_0.84N coating was found to be an excellent ARC against incident light compared with other ARCs. This material also exhibited good light trapping over a wide wavelength spectrum, which produced highly efficient solar cells. The unique and strong polarization, as well as the piezoelectric effect, of the quaternary-nitrides was employed to reduce surface recombination velocities and enhance the solar cell performance. A solar cell with reasonable conversion efficiency of 9.74% was obtained when the n-Al_0.08In_0.08Ga_0.84N/p-Si was employed.     

Innovative light-collecting module using prismatic array structures

Presently, energy conservation and carbon dioxide emission reduction have become increasingly important because of global warming. Using solar energy, which is considered as one of the most important renewable energy sources, does not only decrease the consumption of fossil fuels, but also slows down the pace of global warming. For indoor illumination, our team has developed a technique called ＂Natural Light Illumination.＂ Instead of using solar cells, our system directly guides sunlight into the interior of a structure. However, the efficiency of the light-collecting module is still low. To address this problem, we propose a new light- collecting module based on a prism array structure with high efficiency. We use optical sinmlation tools to design and simulate the efficiency of the module, which is found to be 57%. This value is higher than that of the original concentrator （i.e., 11%）.     

大面积染料敏化太阳电池的串联阻抗特性研究

在电子扩散微分方程的基础上,研究了染料敏化太阳电池光生电流和光生电压随光照强度不同的变化关系.提出敏化太阳电池串联阻抗功率损耗模型,理论模拟了大面积电池（有效面积>1 cm²）光电转换效率随多孔薄膜有效面积宽度变化的曲线、透明导电基底膜与银栅极的比接触电阻以及在不同入射光强下银栅极体电阻对大面积染料敏化太阳电池光伏性能的影响.结果表明透明导电基底膜的方块电阻和银栅极体电阻对大面积染料敏化太阳电池的性能有很大影响,而这种影响随光强的减弱逐渐减小. 关键词： 染料敏化 太阳电池 串联阻抗 光电转换效率     

Calibrated numerical model of a GaInP–GaAs dual‐junction solar cell

In this letter a calibrated numerical model of a III–V dual‐junction solar cell including tunnel diode and Bragg reflector is presented. The quantum efficiencies of the subcells are computed by using the principle of current‐limitation in monolithic multi‐junction solar cells. A special procedure with bias‐illumination and bias‐voltage was implemented. Numerical simulations are used to study the influence of the top cell thickness on the cells' quantum efficiency and on the current‐matching condition. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Efficiency characteristics of a silicon oxide passivation layer on p-type crystalline silicon solar cell at low illumination

Silicon dioxide (SiO₂) is widely used to improve the surface passivation properties of silicon solar cells. To minimize solar cell potential-induced degradation when the PV module is installed outdoors, a silicon oxide film is widely used as an insulator. However, experiments have confirmed that solar cells with a silicon oxide (SiO₂) film have a lower efficiency than solar cells without a silicon oxide (SiO₂) film at low illumination (<0.4 sun). Actually, the efficiency in the low illumination condition affects the average power output per day because the PV module mostly operates when the solar irradiation dose is less than 1 sun. To maximize the performance of the PV module, the output at a low light intensity level should also be considered. Shunt resistance (R_shunt) is known to cause a decrease in solar cell efficiency under low illumination conditions. PC1D simulation was used to analyze parameters, such as the series resistance, parallel resistance, and surface recombination, that affect the characteristics of the solar cell at low light intensity. In this study, we confirmed how the SiO₂ layer affected the low illumination properties of solar cells, even though these cells were more efficient at 1 sun. Silicon solar cells with a SiN_x/SiO₂ bilayer or a SiN_x single film were fabricated, and their characteristics were evaluated. Passivation characteristics were measured using the quasi-steady-state photoconductance (QSSPC) technique to evaluate the minority carrier lifetime and the implied open-circuit voltage (V_OC), and capacitance-voltage measurements were used to analyze the fixed charges. The values of the shunt resistance and series resistance in solar cells with different passivation layers were compared, and the cause of the decrease in the efficiency under low illumination was also analyzed via fill factor calculation.     

Capacity for non-Kolmogorov turbulent optical links with beam wander and pointing errors

The performance of optical wireless communication links depends strongly on the atmospheric conditions and the parameters of the link such as the propagation distance, the operation wavelength, jitter variance, attenuation coefficient and effective beam spot radius at the receiver. The analytical expression for the evaluation of the average capacity of optical wireless communication systems is derived, using the gamma-gamma distribution in the non-Kolmogorov atmosphere turbulence. The impact of atmospheric attenuation, beam wander and pointing errors on the average of the optical wireless communication link is investigated. It is shown that the capacity has a fluctuation curve, when power law α increases, and the power law α of minimum point in fluctuation curve is bigger as the non-Kolmogorov turbulence strength is stronger.     

Spectral-splitting concentrator photovoltaic modules based on AlGaAs/GaAs/GaSb and GaInP/InGaAs(P) solar cells

A concentrator photovoltaic module with sunlight spectral splitting by Fresnel lens and dichroic filters is developed. The photoelectric conversion efficiency of such a module is estimated at a level of 49.4% when three single-junction cells are used and may reach 48.5–50.6% when a tandem two-junction cell is combined with narrow-band cells. Single-junction AlGaAs, GaAs, GaSb, and InGa(P)As solar sells are fabricated by zinc diffusion from the vapor phase into an n-type epitaxial layer. GaInP/GaAs cascade solar cells are prepared by MOS hydride epitaxy. The overall efficiency of the three single-junction solar cells developed for the spectral-splitting module is 38.1% (AM1.5D) at concentration ratio K _c = 200x. The combination of the solar cells with the cascade structure demonstrates an efficiency of 37.9% at concentrations of 400–800 suns. The parameters of the spectral-splitting photovoltaic module are measured. The photovoltaic efficiency of this module reaches 24.7% in the case of three single-junction cells and 27.9% when the two-junction and single-junction cells are combined.     

III-V compounds for solar cell applications

Research activities in the field of III-V solar cells are reviewed. III-V compound semiconductors are used for space solar cells, concentrator solar cells, and in thermophotovoltaic generators. The epitaxial growth of ternary and quaternary material by MOVPE and LPE allows us to realize various band gaps. Multi-junction solar cells with different band gaps are necessary to obtain efficiencies larger than 30%. Recent results of the III-V solar cell research at the Fraunhofer ISE are presented. A mechanically stacked GaAs/GaSb tandem concentrator solar cell achieved an efficiency of 31.1% under 100×AM1.5d. An efficiency of 23% for a two-terminal concentrator module (486 cm²) with Fresnel lenses has been measured under realistic outdoor conditions. Received: 1 March 1999 / Accepted: 28 March 1999 / Published online: 24 June 1999     

基于量子点的荧光型太阳能聚光器

近年来,量子点在结构可控、光谱调节和光学稳定方面的研究进展,表明基于量子点的聚光器件表现出优于基于传统有机染料分子的光输出性能。量子点聚光器成为目前量子点研究领域的新方向。量子点在宏量制备和绿色制备方面的深入研究,使得量子点的制造成本逐步降低,基于量子点的聚光器具有光电转换效率和成本上的优势。本文综述了量子点聚光器的研究进展,主要包括荧光型聚光器的优点、聚光器对量子点光学性质的要求、器件制备的工艺和器件的性能表征方法。重点阐述了量子点的太阳光吸收能力、荧光量子产率和重吸收等关键因素对聚光器件性能的影响,同时介绍了该领域目前最新的研究方向,展望了廉价太阳能窗户在未来城镇建筑上的潜在应用。     

Analysis of 2.5 Gbit/s GPON downlink optical-receiver performance

In the gigabit-capable passive optical network (GPON) optical communication system, the selection of fiber and system performance-analysis is the key links for the realization of system function. Especially the characteristic budget and parameter setting of downlink receiver are topped the list. The analysis of receiver power penalty can reduce the influence on receiver sensitivity and bit error rate (BER) that caused by waveguide dispersion and pulse widening. This article will simulate the performance of GPON downlink receiver, then analyze typical characteristics such as Four Wave Mixing (FWM), Erbium-Doped Fiber Amplifier (EDFA), system eye pattern and Q factor and so on, so as to validate the feasibility of the optical downlink.     

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.     

A compact and high-power silicon-wafer solar strip-cells-array module integrated with an array concentrator

A compact, low-cost and high-output-power silicon-wafer solar strip-cells-array module(SCAM) was experimentally demonstrated. The proposed SCAM consisted mainly of a silicon-wafer strip-cell sparse array and low-concentrationratio array concentrator based on an epoxy resin polymer(ERP) cylindrical plano-convex lens. A polymer replication process based on a polydimethylsiloxane mold was used to fabricate the ERP lens array concentrator. The results show that 46.94% of the silicon-wafer cell was saved in the designed SCAM. Moreover, the output power of the SCAM with a low concentration ratio of 8 suns was improved by 8.6%, compared with a whole piece of a conventional silicon-wafer solar cell with the same area as the module. The proposed method encapsulating solar cells provides a means to reduce the usage of silicon cells in modules as well as improving the output power of modules.