标准测试条件下人造太阳光源的谱失配及影响

标准测试条件下,人造太阳光源的光谱形式、辐 照强度、光谱失配因子等是影响太 阳电池器件测试结果准确性的重要因素。本文以标准太阳光谱AM1.5 为参考,从光谱失配角 度,计算和分析了4种常用人造太阳光源(Arc lamp灯、Q-Flash灯、Q-Flash W灯和ELH 灯)与标准太阳光谱AM1.5之间的光谱失配因子的变化和这四种人造 太阳光源辐照下晶硅电 池的输出参数的变化。计算结果表明:Arc lamp型人造太阳光源的光谱失配因子为 0.979, 晶硅电池输出参数最接近标准太阳光谱AM1.5辐照下的输出参数 ;因光谱失配影响,4种不同人造太阳光源辐照下晶硅电池的输出参数较标准太阳光谱AM1.5辐照下的输出 参数会发生明显变化。     

Industrial solar cell tester: study and improvement of I‐V curves and analysis of the measurement uncertainty

Determination of solar cell parameters by illuminated I–V measurement is a standard characterisation technique in the photovoltaic industry. These measurements are carried out under standard conditions (STC: 25 °C, 1000 W/m² AM1.5G spectrum). It can be considered as the most crucial in‐line test for solar cells as it provides the industry with the conversion efficiency, and it is also a reliable quality control test. Reference cells are mainly used in testing equipment to set irradiance and working conditions in the tester/sorter, the rest of the cells being measured and classified by comparison with that reference. An accurate calibration of the irradiance at STC in cell testers and high precision in determining the main parameters of the I–V curve are required; a suitable design of the mechanical components and an adequate selection of different programme options should be made (distribution of the points measured, temperature correction or classification method). Here, we have studied the accuracy of an industrial solar simulator whose mechanical, electrical, electronic and software components were analysed with an individual solar device and a production sample. An uncertainty analysis was carried out in order to determine the power uncertainty and which components to improve in order to reduce it. Copyright © 2015 John Wiley & Sons, Ltd.     

大光斑高均匀度发散式太阳模拟器设计

为了实现大光斑直径高均匀度太阳辐照模拟,设计了大光斑发散式太阳模拟器。根据太阳光谱分布特性选取短弧氙灯作为光源,建立光源功率计算模型;基于成像倍率和氙弧峰值点离焦量之间的关系,优化设计聚光系统和光学积分器,提高太阳模拟器的辐照均匀度;同时,结合短弧氙灯的光谱特性,建立光谱匹配模型,设计光学滤光片在不同波长的透过率。实验结果表明:设计的发散式太阳模拟器辐照面积为2 m,当工作距离为6、8、10 m时,辐照不均匀度分别优于3.33%、3.51%和4.3%,且光谱与AM1.5太阳光谱A级标准相匹配。     

Accurate measurement,using natural sunlight,of silicon solar cells

The light source is very important when measuring solar cells. Commonly used light sources—good‐quality solar simulators—are expensive and have far from ideal characteristics. Computer modelling described in this work strongly suggests that testing of silicon solar cells under natural sunlight is simpler, cheaper, and more accurate than all but the most careful simulator measurements. Direct‐beam solar spectra were generated with the model SMARTS2 for a range of atmospheric conditions, and a broad range of silicon cells (efficiencies 6–25%) were then simulated under these spectra. These simulations showed that measurement uncertainty of less than 5% should be achievable. Climate data for locations within 45° of the equator show that the required atmospheric conditions should occur commonly in summer. Finally, it is shown that the important atmospheric conditions can be measured without expensive equipment. Copyright © 2004 John Wiley & Sons, Ltd.     

Accurate Measurement and Characterization of Organic Solar Cells

Methods to accurately measure the current–voltage characteristics of organic solar cells under standard reporting conditions are presented. Four types of organic test cells and two types of silicon reference cells (unfiltered and with a KG5 color filter) are selected to calculate spectral‐mismatch factors for different test‐cell/reference‐cell combinations. The test devices include both polymer/fullerene‐based bulk‐heterojunction solar cells and small‐molecule‐based heterojunction solar cells. The spectral responsivities of test cells are measured as per American Society for Testing and Materials Standard E1021, and their dependence on light‐bias intensity is reported. The current–voltage curves are measured under 100 mW cm^–2 standard AM 1.5 G (AM: air mass) spectrum (International Electrotechnical Commission 69094‐1) generated from a source set with a reference cell and corrected for spectral error.     

基于可调谐激光器的太阳光谱辐照度仪定标方法

太阳光谱辐照度仪是利用棱镜分光技术对太阳直射辐射进行连续光谱测量的新型仪器,为了实现高精度观测要求,开展了基于可调谐激光器的系统级定标方法研究。使用激光导入积分球产生的均匀辐照度场作为定标光源,利用标准辐照度探测器作为传递标准,将低温绝对辐射计的辐射标准传递到太阳光谱辐照度仪。在仪器的870 nm波段进行了定标实验,与标准灯法、Langley法得到的定标系数进行比对,偏差分别为2.84%和4.08%,验证了该方法的可行性。根据不确定度评估规范,这种定标方法的不确定度优于0.882%,可以用于高精度的太阳光谱辐射观测。     

光谱型太阳辐射观测仪光学系统设计

为了实现太阳光各波长下观测,针对现有的太阳辐射观测仪光谱测试范围窄、光谱分辨率低的缺点,提出了一种运用光谱测量技术实现高分辨率太阳观测仪光学系统的设计方案。结合太阳辐射观测仪的使用环境与太阳光的特点,利用光纤、余弦校正器等器件设计了太阳辐射观测仪的收光系统。根据太阳光的光谱范围以及光谱分辨率的要求,设计了多通道、高分辨率的太阳辐射观测仪分光系统。实验与设计结果表明:光谱分辨率优于20 nm,能够实现太阳的光谱观测。满足太阳辐射观测仪宽光谱、纳米分辨率等要求。     

太阳模拟器AM0型滤光片及其稳定性研究

太阳模拟器作为航天科技卫星空间环境模拟和太阳能电池检测与标定的必要模拟设备,越来越受到人们的关注。太阳模拟器滤光片作为模拟器的核心部件,通过对模拟器光源滤光,可以得到不同的太阳光谱辐照度。文中研究的AM0滤光片通过对氙灯光源滤光,可以得到大气层表面的太阳光谱辐照度分布。根据标准AM0光谱辐照度曲线和标准氙灯辐照度曲线,得到AM0滤光片透过率曲线。在此基础上对滤光片进行膜系设计和镀制,得到了满足国标A类标准的AM0滤光片。对滤光片进行了紫外辐照实验和高温烘烤实验,研究了其光学稳定性,所镀制的滤光片光学稳定性优于目前使用的滤光片。     

Portable solar simulator

A special-purpose solar simulator developed for the International Space Station offers portability and accurate normalised AMO spectrum. It includes a tungsten lamp serving as a gray-body radiator with a 3200 K temperature, and a mosaic of filters so the filtered lamp output has the same normalised spectral irradiance as that of sunlight, outside Earth's atmosphere.     

Is conversion efficiency still relevant to qualify advanced multi‐junction solar cells?

For better conversion of sunlight into electricity, advanced architectures of multi‐junction (MJ) solar cells include increasing numbers of subcells. The Achilles' heel of these cells lies in their increased sensitivity to the spectral distribution of sunlight, which is likely to significantly alter their performance during real working operation. This study investigates the capacity of MJ solar cells comprising up to 10 subcells to accommodate a wide range of spectral characteristics of the incident radiation. A systematic study is performed, aimed at a realistic estimation of the energy output of MJ‐based concentrating photovoltaic systems at characteristic locations selected to represent a large range of climatic conditions. We show that optimal MJ architectures could have between 4 and 7 subcells. Beyond seven subcells, the slight gains in peak efficiency are likely outweighed by detrimental increases in dependence on local conditions and in annual yield variability. The relevance of considering either conversion efficiency or modeled energy output as the most appropriate indicator of the cell performance, when considering advanced architectures of MJ solar cells, is also discussed. Copyright © 2016 John Wiley & Sons, Ltd.     

2.4m太阳模拟器设计

针对目标特性研究需求,设计了有效辐照面直径2.4 m的太阳模拟器。要求辐照面内的照度不小于0.3个太阳常数,出射光束准直角不大于1且被照面的不均匀度不大于3%,光谱失配误差达到Ｃ级。太阳模拟器主要由四个短弧氙灯、四个椭球面反射镜、两个平面反射镜、一组积分器和一个准直反射镜组成。对设计结果进行了软件仿真分析和实验测试。测试结果表明:太阳模拟器的有效光斑直径为2.43 m,被照面平均照度为3 382 lx,光束准直角0.97,不均匀度为2.8%,光谱失配误差达到Ｃ级,满足设计要求。     

Determination of spectral variations by means of component cells useful for CPV rating and design

A methodology is presented to determine both the short‐term and the long‐term influence of the spectral variations on the performance of multi‐junction (MJ) solar cells and concentrator photovoltaic (CPV) modules. Component cells with the same optical behavior as MJ solar cells are used to characterize the spectrum. A set of parameters, namely spectral matching ratios (SMRs), is used to characterize spectrally a particular direct normal irradiance (DNI) by comparison to the reference spectrum (AM1.5D‐ASTM‐G173‐03). Furthermore, the spectrally corrected DNI for a given MJ solar cell technology is defined providing a way to estimate the losses associated to the spectral variations. The last section analyzes how the spectrum evolves throughout a year in a given place and the set of SMRs representative for that location are calculated. This information can be used to maximize the energy harvested by the MJ solar cell throughout the year. As an example, three years of data recorded in Madrid shows that losses lower than 5% are expected because of current mismatch for state‐of‐the‐art MJ solar cells. Copyright © 2015 John Wiley & Sons, Ltd.     

Short‐circuit current of solar cells under artificial light

A model to estimate the short‐circuit current of a solar cell under artificial light from the short‐circuit current of the same solar cell under AM1.5 1 kW/m² is described. The results may help designers of solar‐powered portable equipment and consumer products working indoors or under a mixture of artificial and sunlight. It is concluded that the ratio of the short‐circuit currents of the same solar cell generated under fluorescent light of 1 lux illuminance divided by the short‐circuit current generated under standard 1 Sun AM1.5 conditions is around 3 × 10⁻⁶ for typical crystalline silicon and CIS solar cells. This value is one order of magnitude greater if the light source considered is an incandescent lamp. In the case of amorphous silicon solar cells the value of the ratio is close to 8 × 10⁻⁶ either for fluorescent or incandescent lamps. CdTe solar cells are also considered, and this factor is about 4 × 10⁻⁶ under fluorescent light, and four times bigger when an incandescent lamp is used. Some measurements performed validate the figures obtained. Copyright © 2002 John Wiley & Sons, Ltd.     

Investigation to estimate the short circuit current by applying the solar spectrum

The influence of the solar spectrum is investigated to estimate the outdoor short circuit current (I_sc) of various photovoltaic (PV) modules. It is well known that the solar spectrum always changes. Hence, it is rare to fit the standard solar spectrum AM1·5G defined in standard IEC 60904‐3. In addition, the spectral response (SR) of PV module is different depending on the material. For example, crystal silicon (c‐Si) has broad sensitivity that the wavelength range is between 350 and 1150 nm; meanwhile, amorphous silicon (a‐Si) has relatively narrow sensitivity comparing to c‐Si. Since I_sc of the PV module decides by multiplying the solar spectrum and SR together, it is necessary to investigate the solar spectrum to estimate the outdoor I_sc in addition to the solar irradiance and module temperature. In this study, the spectral mismatch is calculated and the outdoor I_sc is estimated in the whole year. Copyright © 2007 John Wiley & Sons, Ltd.     

Comparison of traceable calibration methods for primary photovoltaic reference cells

The calibration of photovoltaic reference cells used as primary laboratory standards for the calibration of photovoltaic devices needs to be traceable to international radiometric standards and SI units. As a contribution to the development of an international standard this paper describes three methods for the calibration of primary photovoltaic reference cells, establishing two independent traceability chains. The solar simulator method is traceable via a standard lamp to the international irradiance scale whereas the global sunlight method and the modified global sunlight method are traceable to the world radiometric reference. The calibration values obtained by the three methods agree with each other within their respective uncertainties and with the world photovoltaic scale within ± 0·8%. Copyright © 2005 John Wiley & Sons, Ltd.     

Towards realization of a large‐area light‐emitting diode‐based solar simulator

Solar simulators based on light‐emitting diodes (LEDs) have shown great promise as alternative light sources for indoor testing of photovoltaic cells with certain characteristics that make them superior to the traditional solar simulators. However, large‐area uniform illumination more suitable for larger cells and module measurements still remain a challenge today. In this paper, we discuss the development and fabrication of a scalable large‐area LED‐based solar simulator that consists of multiple tapered light guides. We demonstrate fine intermixing of many LED light rays and power delivery in the form of a synthesized AM 1.5 spectrum over an area of 25 cm × 50 cm with better than 10% spatial nonuniformity. We present the spectral output, the spatial uniformity, and the temporal stability of the simulator in both the constant current mode and the pulsed‐mode LED operation, and compare our data with the International Electrotechnical Commission standards on solar simulators for class rating. Although the light intensity with our current design and settings falls short of the standard solar AM 1.5 intensity, this design and further improvements open up the possibility of achieving large‐area, high‐power indoor solar simulation with various desired spectra. Copyright © 2011 John Wiley & Sons, Ltd.     

Multijunction solar cell model for translating I–V characteristics as a function of irradiance,spectrum, and cell temperature

We describe here a lumped diode model for concentrator multijunction solar cells, in which the temperature, irradiance and spectrum dependences are explicitly included. Moreover an experimental method based on it for the prediction of the I‐V curve under any irradiance‐spectrum‐temperature conditions from a single input measurement is proposed and applied to a set of commercial triple‐junction solar cells in order to demonstrate its validity. Component ‘isotype’ cells are used as reference cells for intensity and spectrum, sparing the measurement of light spectrum and cell spectral response. Finally, a mean RMS prediction error of 0.85% over a range of 100X‐25°C to 700X‐75°C is reported for the whole set when the model parameters inherent in the cell are assumed to be the same for every sample. If optimum parameters are extracted for every cell, the RMS error is reduced to 0.53%. Copyright © 2010 John Wiley & Sons, Ltd.     

彩色成像亮度计用于显示测量及其不确定度分析

彩色成像亮度计能在几秒钟之内一次完成数以万计个物点的测量,因此它非常适合于测量显示器的亮度、颜色及其分布.分析了彩色成像亮度计测量 CRT 和 LCD 显示器的不确定度,主要分析了光谱失配所引入的不确定度,结果表明系统响应的光谱失配造成了较大的测量不确定度.介绍了一种应用于彩色成像亮度计测量 CRT 和 LCD 显示器的光谱校正方法,结果表明这种校正方法能有效减少测量不确定度.     

Effects of spectrum on the power rating of amorphous silicon photovoltaic devices

The effects of different spectra on the laboratory based performance evaluation of amorphous silicon solar cells is investigated using an opto‐electrical model which was developed specifically for this purpose. The aim is to quantify uncertainties in the calibration process. Two main uncertainties arise from the differences in the test spectrum and the standard spectrum. First, the mismatch between reference cells and the measured device, which is shown to be voltage dependent in the case of amorphous silicon devices. Second, the fill factor of the device is affected by different spectra. Different cell structures and states (specifically different i‐layer thickness and levels of degradation) for the different light sources are investigated in this work. These sources are different solar simulators, LED sources, Tungsten as well as the standard terrestrial AM1.5G radiation. It is shown that the performance cannot be evaluated by short circuit current alone. The voltage dependent quantum efficiency of p‐i‐n devices can introduce a mismatch in the P_MPP of 1% for 250 nm i‐layer devices in as prepared state, rising to up to 4% for the 600 nm i‐layer devices at degraded state. Copyright © 2011 John Wiley & Sons, Ltd.     

Radial CPV receiver

Concentration Photovoltaic (CPV) parabolic dishes uses to concentrate the sunlight creating a spot of light with radial symmetry, which does not match with the conventional rectangular solar cells receivers. Our approach for reducing the severe optical mismatch consists of using a receiver with radial arrangement of the cells into circular sectors that can minimise the current mismatch. It guarantees that the circular sectors are receiving the same amount of light due to their radial distribution. On the other hand, when tracking errors move the focus off the central position, interconnection of opposite circular sectors in parallel can compensate the current mismatch and so the power losses are significantly reduced. Copyright © 2010 John Wiley & Sons, Ltd.