用电学参数表征晶体硅太阳电池特性

为了分析3种不同类型的商业太阳电池片,即P型铸造多晶硅太阳电池、定边喂膜生长硅(EFG)太阳电池和单晶硅太阳电池中存在的影响电池效率的可能性缺陷,对太阳电池的电性能参数如光谱响应曲线、短路电流的二维分布、串联电阻、并联电阻、二极管理想因子、反向饱和电流等进行了表征和分析.对比分析了对太阳电池增加偏置白光前后的光谱响应(外量子效率EQE)曲线,然后采用光束诱导电流(LBIC)法和电流-电压(I-V) (暗,光照)法分别测试了太阳电池中形成漏电缺陷的面分布和太阳电池的电性能参数并借助于太阳电池的二极管等效模型拟合了I-V曲线.结合这3种分析测试方法,得出在铸造多晶硅、EGF太阳电池中影响电池参数的主要缺陷是晶界、位错以及材料中的杂质,而影响单晶硅太阳电池的却是存在于体内的金属杂质等.由于原材料中存在不同的少子复合中心,使最终多晶硅,EFG和单晶硅太阳电池的转换效率分别为10.5%,11.7%和15.7%.     

太阳电池测试系统及其参数匹配优化研究

为了获得太阳电池的I-V特性曲线及特性参数,利用Visual C++语言开发出基于Windows平台的太阳电池测试软件系统,并对基于补偿原理的I-V测试电路参数匹配进行了详细分析。电路中串联电阻及桥式直流电源对电池的暗特性影响变化不大,但可使光特性I-V曲线发生显著变化。通过参数匹配的调整与优化,测量数据与电池的标准数据基本吻合,其误差仅为1%~2%,表明该测试软件系统满足实际使用要求,为电池性能分析提供了准确的依据。     

缺陷太阳电池EL图像及伏安特性分析

本文基于电致发光（Electroluminescence,EL）的理论,利用红外检测的方法,通过CCD近红外相机实验检测出了晶体硅太阳电池中存在的隐性缺陷,如隐裂、断栅、电阻不均匀、花片等,并将可见光下电池图像与EL图像进行对比。对存在缺陷的太阳电池进行了伏安特性测试,得出隐裂缺陷对太阳电池伏安特性、填充因子、效率等性能的影响,也证明电致发光技术检测太阳电池缺陷的准确性。     

基于嵌入式技术的太阳电池I-V性能测试仪

设计了一款基于嵌入式技术的手持式太阳电池I-V性能测试仪.该测试仪以ARM920体系芯片S3C2440为核心,通过采集太阳电池电压、电流、光强和温度4路信号并通过对信号数据的处理,测得太阳能电池开路电压、短路电流、最佳工作点、串联电阻、并联电阻、电池效率等关键参数,并在触摸屏上实时显示I-V曲线.目前该项目已完成系统硬件设计与调试和测试界面程序的设计.调试结果表明系统工作稳定,系统功耗小.界面简洁、运行流畅、操作简单.     

一种智能太阳电池测试仪的研究

智能太阳电池测试仪能以特定的太阳光模拟器，通过新颖的测试电路，精确地得到开路电压V∝、短路电流J∝等参数，并能快速的绘制I-V曲线与P-V曲线。能适应太阳电池单件与组件测试，具备自动换档功能。     

电磁感应对硅光伏电池可视化检测技术的改性

硅光伏电池对检测技术的需求贯穿于研发、生产、服役和维修等过程。探索电磁感应(EMI)对光伏电池缺陷检测用电致热成像(ET)和电致发光(EL)的影响,并进行改性研究。在研究ET热辐射和EL光辐射原理的基础上,分析涡流生热对热辐射和光子辐射等物理过程的影响。提出基于电磁感应和电致热光辐射的光伏电池无损检测方法,实现了单晶硅光伏电池断栅、划痕、断角、杂质掺杂、表面涂层污染、隐裂、黑芯片和多晶硅光伏电池划痕、碎片等不同类型缺陷的可视化检测。通过实验对比分析了两个功率下的ET和EL成像,定性结果表明,电磁感应能够大幅提高ET和EL对缺陷的检测能力。     

太阳电池测试系统的研制

为了获得太阳电池的基本性能参数,研究太阳电池动态行为及光电转换机制。我们采用labview8.5语言和光脉冲技术,研制了一套太阳电池测试系统。该系统实现了I-V曲线、电荷提取、光电压衰减、光脉冲扰动瞬态的电池行为测试,可以获得太阳电池的开路电压、短路电流、填充因子、光电转换效率等基本性能参数以及电子扩散系数、电子寿命、电子扩散长度等微观性能参数。本系统已在染料敏化太阳电池研究中获得了重要实验结果。     

a—Si：H薄膜光电二极管应用于数字照度计的研究

本文分析了工艺参数和结构设计对a—Si:H薄膜光电二极管的光谱响应、灵敏度和暗电流等主要特性的影响,推导出元件外接负载时光生电压与光照度的关系式,并引入临界照度概念,定量地讨论了元件的输出线性精度。同时,本文给出了元件应用于数字照度计时的光谱修正和放大电路。检定结果表明,元件性能明显优于单晶硅光电二极管等传统光电元件,在可见光检测领域具有广阔的应用前景。     

表面反型结构的紫硅光电探测器

采用常规扩散方法形成PN结的普通硅光电二极管,结深为几个微米,光谱响应灵敏度的峰值约在8500埃左右,短波响应很低,当4500埃时,几乎无响应。其原因主要是两方面,一是硅材料质量和工艺水平,即硅单晶或外延层复合中心较多;或扩散杂质的表面浓度太高和晶格缺陷多,工艺过程杂质     

封装标准太阳电池性能及其与国际标准一致性的评价

基于国际电工委员会(IEC)国际标准分析了引起标准太阳电池量值传递误差的因素及其与国际标准的一致性。随机选取我国市场上销售的6种封装标准太阳电池,测量了它们的温度特性、光谱响应特性和表面反射特性。结果表明:电池的封装结构影响它们的冷却效果及温度的正确测量,从而导致温度和短路电流的不稳定性,其变异系数最高可达0.12%和0.04%。另外,有、无偏置光条件下的光谱响应特性均反映其光电流的光照强度线性特性,这里定义用光谱拟合度来衡量各封装太阳电池的光谱响应特性。采用改变入射角测量短路电流的方法分析了表面光反射对短路电流的影响,利用余弦函数拟合确定了由表面反射光所引起的短路电流的误差可达0.21%。本文的研究成果对光伏行业正确制造、选择和使用标准太阳电池具有指导作用。     

High saturation solar light beam induced current scanning of solar cells

The response of the electrical parameters of photovoltaic cells under concentrated solar irradiance has been the subject of many studies performed in recent times. The high saturation conditions typically found in solar cells that are subjected to highly concentrated solar radiation may cause electrically active cell features to behave differently than under monochromatic laser illumination, normally used in light beam induced current (LBIC) investigations. A high concentration solar LBIC (S-LBIC) measurement system has been developed to perform localized cell characterization. The responses of silicon solar cells that were measured qualitatively include externally biased induced cell current at specific cell voltages, I(V), open circuit voltage, V(oc), and the average rate of change of the cell bias with the induced current, DeltaV/DeltaI(V), close to the zero bias region. These images show the relative scale of the parameters of a cell up to the penetration depth of the solar beam and can be obtained with relative ease, qualifying important electrical response features of the solar cell. The S-LBIC maps were also compared with maps that were similarly obtained using a high intensity He-Ne laser beam probe. This article reports on the techniques employed and initial results obtained.     

晶体硅光伏电池的标准测试

为了建立太阳电池的标准测试规范流程,对影响太阳电池标准测试不确定度的各类因素进行了评价和筛选。基于太阳光模拟器、分光感度仪、IV测试仪、标准太阳电池等二级太阳电池标准测试设备与器件,开展了多项标准测试技术的研究。对电池测量过程中太阳电池模拟光源的空间不均匀性、时间不稳定性、仪器测量重复性、扫描方向导致的不确定度、电池反射率和透射率、面积测量不确定度、量子效率等各类影响因素进行了测量,给出了高效晶体硅太阳电池测量不确定度的测量流程,最终导出在现有实验室测量条件下的扩展测量不确定度为±3.94%。基于对常规太阳电池测试数据的比较,对常规电池测量方法进行了改进,将测量不确定度降低了0.19%。最后,提出了双面电池的精确测试流程和方法,为其它双面光电池的标准化测量提供了借鉴。     

光束诱导电压成像研究

在光束诱导电流（Light Beam Induced Current,简称LBIC）成像技术的基础上,我们从理论和实验上分析了光束诱导电压（Light Beam Induced Voltage,简称LBIV）成像的机理。通过建立光束诱导电压成像的理论模型,认为光束诱导电压成像的测量值是一个平衡电压值,而不是光照区域的局域开路电压,我们在一块复合分布不均匀的单晶硅太阳能电池上验证了这个结论。这为改进光束诱导成像技术奠定了基础。     

高效太阳能电池快速烧结设备的系统与工艺研究

在太阳能电池片的制作过程中,“烧结”是一道很重要的工序,其制作的过程就要用到快速烧结炉。其作用就是把印刷到硅片上的电极在高温下烧结成电池片,最终使电极和硅片本身形成欧姆接触,从而提高电池片的开路电压和填充因子2个关键参数,使电极的接触具有电阻特性,达到生产出高转换效率电池片的目的。故快速烧结炉的结构设计及工艺运行状态的好坏直接影响到电池片的质量,所以好的烧结设备的设计和烧结工艺是密不可分的。本文详述了高效太阳能电池快速烧结设备的部件设置,并对设备进行剖析,说明设计精良的烧结设备是工艺提升的基础。     

Experimental analysis and computer simulation of a methodology for laser focusing in the solar cell characterization by laser beam induced current

This paper presents a quick methodology for focusing a laser beam on a photoactive surface based on performing a single line scan while simultaneously modifying the laser's position over the surface and the distance between the focusing lens and the active surface. The methodology was tested using the computer simulation technique. Several configurations were computer simulated by programming different experimental situations to discover the situations in which this focusing methodology would provide optimum results. The conclusions obtained from computer simulation methodology were checked by means of experimental tests using several solar cells, such as a thin-film amorphous silicon solar cell, a monocrystalline silicon solar cell, and a polycrystalline silicon solar cell. From the tests performed, we concluded that optimum focusing is achieved in systems in which the laser beam induced current signal generated by the photoactive surface has no large heterogeneities (e.g., fingers or grain boundaries), artefacts, or defects. Thus, the best results are achieved in systems where the surface of the photovoltaic device has a certain degree of homogeneity.     

A study on soldering characteristics of laser tabbing system for crystalline silicon photovoltaic module production

The most significant task in the solar cell industry today is to minimize the cost of solar cell development, thereby establishing grid parity early. One way to achieve this goal is to reduce the thickness of silicon solar cell, which would subsequently result in reduction in raw silicon material costs. The most commonly used tabbing process in solar cell production today is the heating bar process. This process utilizes electric heating bars to heat the ribbons on solar cells. In this study, a laser tabbing machine was developed to overcome the problems of tabbing process of heating bar technique for a thin crystalline silicon solar cell. An electric test and peeling test were executed on soldering ribbon on solar cells. The results indicate that the bonding force of ribbon does not affect electrical output of the solar cell. The electric power of soldered solar cell was decreased around 5% in output as compared to the original unsoldered solar cell. The electric powers of the laser soldered module and the heating-bar soldered module were very close. The decline in efficiency of both modules was about 1.13%. As a result of this study, it was confirmed that the laser tabbing system developed in this research can be applied in module manufacturing processes.     

SI太阳能电池温度特性测量装置的设计

通过对半导体制冷原理及温度对太阳能电池主要表征参数影响等的讨论,解决了LED光源驱动、散热、太阳能电池温控等技术问题,设计出太阳能电池的温度特性测试装置,并利用该装置对Si太阳能电池特性参数进行了测量,测试结果与理论讨论相符,对提高太阳能电池的生产工艺水平和研究太阳能电池片的性能有重要参考价值。     

Thermal deformation analysis of tabbed solar cells using solder alloy and conductive film

Finite element analysis (FEA) has been carried out with the aim of understanding the thermal deformation characteristics of two solar cell configurations. One of the solar cell models is tabbed by lead-free solder, the other model by Conductive film (CF). A high temperature soldering process could weaken the bond and reduce the reliability of the cells because of the residual stress caused by the different thermal expansion coefficients of the materials. Moreover, solar irradiation generates temperature distribution across the surface of the solar cell, and the development of solar cells made of thinner crystalline silicon wafers will lead to the reduction in manufacturing costs. In this study, Finite element analysis (FEA) of the manufacturing process has been carried out using both solder and CF bonding. Three temperature cycles were applied to analyze different environmental operating conditions and understand how thermal cycles affect the residual stress during actual service conditions. This investigation provides a comparison of thermal deformations between solder and CF bonded solar cells in order to understand which offers substantial reliability in the long term. Also this study explores the effects of various thicknesses of the silicon wafer on the residual stress and deformation of the solar cells.     

I–V curve characteristics of solar cells on composite substrate under mechanical loading

This research is aimed to conduct a characterization of I–V (current-voltage) curve changes in order to interpret the effects of physical defects such as microcracks of solar cells installed over structures to which mechanical load is applied on the power generation performance of solar cells, as well as to conduct fractography to interpret causes for reducing the power generation performance of the cells. To accomplish this, tensile specimens to which a mechanical load would be applied were produced using composite materials, which are representative light materials and solar cells that were attached to the specimens using the adhesive property of EVA film. In the experiment, mono-crystalline silicon solar cells were used, which are breakable and whose efficiency is approximately 24.2% (lab.). Also, in order to evaluate the power generation performance of solar cells under mechanical loading in real-time, a measuring device was designed to compare and evaluate the time point and property of fracture under mechanical loading. Moreover, fractography was conducted to analyze and consider causes for reducing the efficiency of solar cells. As a result of the experiment, it was found that the mechanical load applied to solar cells caused cracks to the surface and interior of the cells, which in turn reduced the I_sc value and the V_oc value of the I–V curve. The present study provides an initial set of valuation parameters in the maintenance and management of installed solar cells when applying solar cell technology to dynamic structures.     

Detection limits for glow discharge mass spectrometry (GDMS) analyses of impurities in solar cell silicon

The measurement of both doping elements and trace elements in solar cell silicon plays a key role for achieving high conversion efficiency of the solar cell device. Doping element concentrations in the range of few hundreds part per billions (ppb) and trace elements in the ppb or sub-ppb concentration range are typically present in multicrystalline silicon wafers for solar cells. Accurate and reliable measurements of these small amounts are not straightforward. The present work describes a fast-flow direct-current high resolution glow discharge mass spectrometer (GDMS). Detection limits for a number of impurities (B, Al, P, Ca, Ti, V, Cr, Mn, Fe, Ni, Co, Cu, Mo, Sn, W and Pb) of interest for solar cell applications have been investigated by GDMS. These detection limits are approximately 1 ppba or below, except for B, Al, P, Ca and Pb. All concentrations reported are quantitative since calculated relative sensitivity factors (RSF‘s) for Si matrix have been used. The detection limits have been achieved with minimum sample preparation and short analysis time.