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.     

Reflection-type single long-pulse solar simulator for high-efficiency crystalline silicon photovoltaic modules

Photovoltaic module measurements are predominantly taken by using pulsed solar simulators. However, significant errors can be generated when the existing simulators are applied to current high-efficiency crystalline silicon photovoltaic modules. This paper presents the design and implementation of a novel solar simulator featuring reflection-type light source and single long-pulse flash. The analysis and experimental study of the capacitance effect and the technical details of the simulator including reflection-type lamp house, xenon flash lamp power supply, and source-measure unit are introduced. The results show that the complete system achieves Class AAA performance in accordance with the international standard. The proposed simulator outperforms other similar products on the market and has been adopted by some well-known photovoltaic module manufacturers. The practical application demonstrates that this high-performance and cost-effective simulator is quite suitable for photovoltaic module production line.     

太阳能发电示范基地的光伏发电试验及效益分析

文章以乾安县气象局太阳能发电示范基地为例,介绍了太阳能光伏发电的总体设计思想和系统组成;阐述了采用多晶硅、单晶硅等多种材料,并以固定式、单跟踪式、全跟踪式多种发电方式的太阳能光伏发电试验,分析了光伏发电的社会效益和经济效益。     

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。     

Investigation of photoconductivity of silicon solar cells by a near-field scanning microwave microscope

The photovoltaic effect in silicon solar cells were investigated by using a near-field scanning microwave microscope (NSMM) technique by measuring the microwave reflection coefficient at an operating frequency near 4 GHz. As the photoconductivity in the solar cells was varied due to the incident light intensities and the wavelength, we could observe the photoconductivity changes at heterojunction interfaces inside the solar cells by measuring the change of reflection coefficient S₁₁ of the NSMM. By measuring the change of reflection coefficient, we also directly imaged the photoconductivity changes at heterojunction interfaces inside the solar cells.     

国产DCS在大型多晶硅生产装置中的应用

多晶硅是太阳能光伏产业和电子工业的基础原料,其发展前景光明。随着国内集散控制系统(DCS)的不断成熟和完善,国产DCS逐步打破了国外DCS长期在多晶硅行业的垄断局面。本文在阐述了1500吨/年多晶硅生产装置中的生产工艺基础上,基于国产ECS-100DCS控制系统完成DCS总体设计和关键控制方案,针对工艺特点提出了多种模式自动控制方案、安全联锁保护、智能设备信息集成方案等,这些成果在1500吨/年多晶硅生产装置上得到成功应用。     

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.     

Instrumentation for accelerated life tests of concentrator solar cells

Concentrator photovoltaic is an emergent technology that may be a good economical and efficient alternative for the generation of electricity at a competitive cost. However, the reliability of these new solar cells and systems is still an open issue due to the high-irradiation level they are subjected to as well as the electrical and thermal stresses that they are expected to endure. To evaluate the reliability in a short period of time, accelerated aging tests are essential. Thermal aging tests for concentrator photovoltaic solar cells and systems under illumination are not available because no technical solution to the problem of reaching the working concentration inside a climatic chamber has been available. This work presents an automatic instrumentation system that overcomes the aforementioned limitation. Working conditions have been simulated by forward biasing the solar cells to the current they would handle at the working concentration (in this case, 700 and 1050 times the irradiance at one standard sun). The instrumentation system has been deployed for more than 10?000 h in a thermal aging test for III-V concentrator solar cells, in which the generated power evolution at different temperatures has been monitored. As a result of this test, the acceleration factor has been calculated, thus allowing for the degradation evolution at any temperature in addition to normal working conditions to be obtained.     

可横向分光的大接收角非成像式聚光系统

以传统聚光系统为基础的聚光电池虽然可以减少电池量,但需要精度高的跟踪装置,同时由于电池的吸收光谱较窄,而太阳光谱却较宽,会浪费很多能量.针对这种弊病,对横向非成像光学系统进行了研究,设计了两套接收角分别为6°和10°,聚光比分别为30和20,电池接收面积均为1 cm×1 cm,并能分光的聚光光学系统.设计结果表明,这些系统的光学效率在接收角范围内均大于90%.该类系统拓宽了太阳光谱的吸收范围,降低了对跟踪系统的要求,与高效太阳电池相结合,可制成高效、便携式、非跟踪太阳电池组件,为野外或战场上应用的技术装备提供电源,从而改善它们的灵活性、耐受性和有效性.     

基于DSP的新型太阳方位跟踪系统

为了提高太阳方位跟踪精度,降低光伏发电系统的成本,利用光伏电池旋转产生的短路电流是交变电流的这一特点,通过离散傅里叶变换（DFT）求解交变电流的初相位,计算太阳的高度角和方位角,实现了对太阳方位的自动跟踪。并依此方法设计出了一套基于数字信号处理器（DSP）的新型太阳方位跟踪系统。实验结果表明,该系统能实现太阳光大范围内检测,并迅速跟踪,可避免多块光敏元件的不一致性所带来的问题,有效地提高了跟踪系统的精确性,可望在太阳能光伏发电工程中得到应用。     

Design and implementation of a low-cost multi-channel temperature measurement system for photovoltaic modules

An efficient and low-cost temperature logging system with a 16-channel input was developed for measurements of photovoltaic module temperature. This paper reports the principle of operation, design aspects, as well as the experimentation and performance of the simultaneous temperature measurement of 16 solar cells/modules. The system consists of a 16 channel multiplexer, a 12 bit A/D, a differential amplifier and NTC temperature sensors. The temperature range of the sensor is from −20 °C to 120 °C. The simplistic design requires no large internal memory to store data but incorporates a high degree of sensitivity and dynamic range (according to climate condition), thus the cost of the design remains low and makes it suitable for field applications. The system was successfully tested for the operating temperature of a 40-cell mono crystalline Si photovoltaic module under realistic outdoor conditions during a summer and a winter day. The temperature Instrumentation developed for avoidance of special interface card use enabled the successful collection of data from long distances with negligible level of noise.     

太阳能级晶体硅中杂质的质谱检测方法

太阳能级晶体硅材料中杂质的种类和含量直接影响太阳能电池的发电效率,因此硅材料中杂质含量和分布的检测至关重要。当今社会光伏产业的迅猛发展,推进了晶体硅检测技术的更新和发展。本文总结了近年来在硅材料杂质检测中所使用的方法以及这些方法的不足;比较了电感耦合等离子体质谱（ICP-MS）、辉光放电质谱（GDMS）、二次离子质谱（SIMS）和激光电离质谱（LIMS）四种可用于太阳能级晶体硅检测的原理和优缺点。     

晶体硅太阳能电池PECVD SiNx：H薄膜工艺研究

通过在工业化生产线上研究了PECVD法沉积Si Nx：H薄膜过程中工艺温度和气体流量对其厚度和折射率的影响、工艺气体流量和射频功率对晶体硅太阳能电池光电转换效率、开路电压以及短路电流的影响,最后研究了PECVD对不同类型晶体硅电池的钝化效果。结果表明,随着气体Si H4流量增加,Si Nx：H膜的厚度和折射率上升;随着温度上升,Si Nx：H膜的厚度先上升后下降,折射率无明显变化规律;对于多晶硅太阳能电池,工艺气体NH3与Si H4流量比为11时,光电转换效率最高,随着射频功率从2800W增至4200W,光电转换效率先上升后下降,3700W时达到峰值;Direct Plasma PECVD对多晶硅太阳能电池的钝化效果好于对单晶硅太阳能电池。     

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.     

太阳能水下航行器光伏系统MPPT控制仿真研究

通过光伏电池的简化模型,研究了光伏电池的输出特性,并分析了BUCK斩波电路寻找最大功率点的实现原理.提出了变步长扰动MPPT策略,并在Matlab仿真环境中开发了带有此策略的仿真模型.利用此模型进行计算机仿真,结果表明,太阳能水下航行器光伏系统变步长MPPT控制,能够准确地跟踪太阳能电池的最大功率点,提高了太阳能电池利用效率.     

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。     

基于PLC光伏发电自动跟踪控制方法在酒泉应用

由于太阳位置随时间而变化,使光伏发电系统的太阳能电池阵列受光照强度不稳定,从而降低了光伏电池的效率,因此,设计太阳自动跟踪器是提高光伏发电系统工作效率的有效措施。该文针对已有的光伏跟踪控制方法的缺陷与不足,考虑到执行电机在转动时间内对太阳位置角度的变化与跟踪误差范围的预测与控制,提出了一种采用PLC的跟踪控制方法,并通过理论分析与Matlab/Simulink仿真结果验证了其可行性,具有很高的推广应用价值。     

一种适用于CPV的太阳模拟器的光学结构与分析

太阳模拟器是聚光光伏(CPV)领域内对电池片、组件及系统进行在线检测的一种必不可少的光源设备,其要求辐照度大于800 W/m2,准直角度小,辐照度均匀,光谱接近AM1.5。要同时达到这些指标有一定的难度。通过分析实现既辐照均匀又辐照准直的太阳模拟器需要克服的因素,提出了一种太阳模拟器结构方案以满足上述要求。同时,配比不同焦距的准直透镜还可实现辐照面积可调。利用ZEMAX软件对该结构进行了仿真,验证了该方案的实现效果。     

Design of Reflective Concentrator Model with Application for Concentrator Photovoltaic System

The nonuniform irradiation in the standard photovoltaic(PV) cells causes their relatively high series resistance,which results in a considerably lowered efficiency of PV cells.Currently the concentrator of uniform irradiation designed for concentrator photovoltaic is rare in China and lack sufficient theoretical research.In this paper,a systematic research on the solar reflective concentrator is conducted.A novel structure for a solar reflective concentrator is designed with the application of a flat mirror matrix to concentrate the sunlight for concentrator photovoltaic(CPV) systems.Sunlight beams are focused through the reflection of the mirror array on the solar cell to generate electricity.The concentrator is capable of producing much more uniform sunlight with a certain concentration ratio.The design scheme includes laying out the flat mirrors,optimizing the optical pathway and the parameters of each mirror.The prototype of the CPV system was installed at Nanjing,China.In the configuration of the prototype,it is composed of 24 pieces parallelogram flat mirrors,which are arranged into a total reflective array of 5 rows and 5 columns.In comparison with the parabolic trough concentrator,the experimental measurements verify such design has high efficiency.The concentrator model of a flat mirror matrix and the proposed new design method will lay a solid foundation for designing the concentrator of uniform irradiation.     

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.