一种高精度解析提取太阳电池参数的新方法

基于太阳电池光生电流远大于反向饱和电流、并 联电阻远大于串联电阻以及光生电流 近似等于负的短路电流3个边界条件,结合太阳电池在短路点、开路点和最大功率点处的极值 表述, 提出了一种解析求解太阳电池光生电流、反向饱和电流、理想因子、并联电阻和串联电阻5个电性参 数的方法,并研究了方法的特点。通过与文献实验数据的对比表明,本文方法不仅具有正确 性,而且 适用于各种条件下的各种类型电池;通过实验表明,本文方法具有较高的计算精 度和速度,误差在2%以下,时间小于0.2s。     

Analysis of the current-voltage characteristic of solar cells

The parameters for the generation-recombination current and diffusion current of a solar cell including series and shunt resistance are determined experimentally by a new method through applying equal current steps to the cell rather than voltage steps. This allows a simple evaluation of the generation-recombination current term in the presence of a low shunt resistance of the cell. In a second measuring cycle the series resistance and the diffusion current term of the cell are determined in a similar way. The presented method is a relative simple and low-cost analysis and it allows a quick and accurate on-line determination of the parameters of the current-voltage characteristic, especially for silicon solar cells.     

光照下太阳电池结品质因子解析的新方法

本文给出一种描述太阳电池在光照条件下其结品质因子的解析表示式。根据这种表示,高效率太阳电池的结品质因子仅利用电池的四个输出参数(V_(oc),I_(sc),V_m和I_m)便可确定。 使用这种方法对所研制的n~+p,MIS/IL和MINP太阳电池的结品质因子分别进行测算,并与已有的测算方法所得结果进行比较,结果表明,此方法具有计算简单,测试方便,数值准确等优点。     

高效太阳能电池

设计了一种可提高太阳能电池吸收太阳光的效率和有效存储能量的方法和装置.介绍了太阳能电池的伏安特性和法拉电容的充放电特性.该装置通过凹面镜实现太阳光的双面吸收,并以法拉电容存储太阳能.和传统单面受光电池以及用蓄电池储电相比,该装置太阳光吸收效率高、法拉电容充电时间快、放电电流大,可广泛适用于路灯及楼道灯照明等领域.     

基于近红外图像的硅太阳能电池故障检测方法

太阳能光伏发电是现今具有远大发展前景的新能源领域,先进高效的太阳能电池制造产业对于太阳能光伏发电具有重要意义,因此生产制造过程中太阳能电池探伤技术具有巨大的应用价值。当前新发展出的利用近红外图像对太阳能电池探伤的技术,对于检测太阳能电池故障比较有效,但当前工业界所使用的后期处理较为简单。通过对太阳能电池近红外图像作一定图像处理,可以较为快捷地分辨出太阳能电池的碎片、隐裂、断栅等故障。相对于已有的后期处理方法,可检测的故障类型较为全面,故障检测效率有较大提高,可以显著降低太阳能电池生产中的太阳能电池故障率。     

A new method to characterize bifacial solar cells

We present a new method to characterize bifacial solar cells under standard test conditions (STC). The method considers the bifacial operation of the cell and provides the characteristics for simultaneous front and rear side illumination rather than providing the front and the rear side characteristics separately. The method involves measurements of front side electrical parameters (efficiency, open‐circuit voltage, short‐circuit current and fill factor) and rear side short‐circuit current under STC. Two new parameters are introduced, namely bifacial 1.x efficiency (effective efficiency) and gain‐efficiency product, which are calculated from the measured STC parameters. The former provides information related to the cell design considering the bifacial operation, whereas the latter provides the end‐use benefits from the modules with bifacial cells for a particular installation. To calculate the bifacial 1.x efficiency and the gain‐efficiency product, a one‐diode solar cell equivalent circuit is used. Characteristic plots are shown for the newly introduced parameters as a function of rear‐side illumination for various example solar cells. A sensitivity analysis is performed to understand the influence of each single‐sided STC solar cell parameter on the newly introduced parameters. This sensitivity analysis shows that the fill factor and the rear‐to‐front current ratio are the most critical parameters for bifacial solar cells. Copyright © 2012 John Wiley & Sons, Ltd.     

Measurement of minority carrier lifetime in solar cells from photo-induced open-circuit voltage decay

We present an experimental technique for determining the excess minority carrier lifetime within the base region of p-n junction solar cells. The procedure is to forward-bias the solar cell with a flash from a stroboscope and then to monitor the decay of the open-circuit voltage. Results are given for conventional horizontal-junction devices, as well as for vertical single- and multijunction solar cells. Lifetimes obtained with this technique are compared with those obtained from a method based on open-circuit voltage decay following the abrupt termination of a forward current, and with results obtained from a traveling light spot measurement of base minority carrier diffusion length in vertical-junction solar cells, from which the lifetime can be inferred. It is found that the forward current method does not yield a reliable lifetime estimate.     

晶体硅太阳电池烧结工艺优化

金属电极与硅的接触电阻是影响太阳电池填充因子和短路电流进而影响光电转换效率的重要因素之一。首先对晶体硅太阳电池的烧结工艺进行了优化,利用平台式烧结温度曲线代替陡坡式烧结温度曲线。然后,采用Core Scan方法测试工艺优化前后晶体硅太阳电池丝网印刷烧结银电极与硅之间的接触电阻Rc,并测试了工艺优化前后电池片的IV特性。数据显示烧结工艺优化后可减小银电极与硅的接触电阻,从而提高了太阳电池的光电转化效率。平台式烧结温度曲线更适用浅结高方阻的电池结构。     

Optimum Design of Dye‐Sensitized Solar Module for Building‐Integrated Photovoltaic Systems

This paper presents a method for determining the optimum active‐area width (OAW) of solar cells in a module architecture. The current density–voltage curve of a reference cell with a narrow active‐area width is used to reproduce the current density profile in the test cell whose active area width is to be optimized. We obtained self‐consistent current density and electric potential profiles from iterative calculations of both properties, considering the distributed resistance of the contact layers. Further, we determined the OAW that yields the maximum efficiency by calculating efficiency as a function of the active‐area width. The proposed method can be applied to the design of the active area of a dye‐sensitized solar cell in Z‐type series connection modules for indoor and building‐integrated photovoltaic systems. Our calculations predicted that OAW increases as the sheet resistances of the contact layers and the intensity of light decrease.     

Investigation of methods used in calculations of solar cell parameters

Analytical expressions have been obtained for extracting the electrical parameters and characteristics of solar cells, including series and shunt resistances, and the saturation current. The method of Lagrange multipliers was used for computing the shape factor of the current-voltage characteristic (CVC) of solar cell. The calculation results demonstrated a satisfactory agreement with experimental data.     

Thermal behaviour of new crystalline semitransparent solar cell structure

This paper presents the structure of a novel semitransparent solar cell and its thermal behaviour, which cell can be used for building integrated applications. The crystalline self-made test cells can be manufactured using basic semiconductor technological steps, arbitrary pattern of holes can be etched. We report on two alternative methods for thermal behaviour characterisation of the novel semitransparent solar cell compared to non-transparent solar cells. The first method is thermal dependence and High Temperature Store (HTS)—condition A testing and the second is application of conventional thermal imaging in combination with electrical current heating of the solar cell. I–V characteristic measurements at preset temperatures demonstrate that the new semitransparent sample despite the throughout holes can be as effective as the without hole solar cell. IR imaging results reveal the localised resistive heating zones or shunting in the test cells. This research examines the influence of the through-holes on the thermal properties of solar cells.     

Characterization of solar cells by thermal transient testing

The current paper deals with the application of thermal transient testing as a characterization tool for solar modules. Based on the measurement of different samples (concentrator solar cell, single junction silicon solar cell) we prove the applicability of this measurement technique and address some specific issues of the characterization of solar cells by the thermal transient method.From the measurement metrics such as junction-to-base plate thermal resistance and thermal capacitance(s) can be derived and can serve as a basis of a multi domain solar cell model. The used technique also enables us to verify the quality of attachment layers in a solar module allowing fair quality control and reliability analysis of these devices. Finally a method is proposed to regain the data that is covered by the initial electric transient following the power step. This initial electric transient can be high in large surface devices like solar cells, and covers valuable data describing the structure near to the p–n junction. To eliminate this, simulated transients were fitted to the part of the actual measured thermal transient where the electric transient already decayed. This way the part of the thermal transient that was covered by the electric transient can be reconstructed.     

Fabrication and Characterization of GaAs Solar Cells on Copper Substrates

This letter presents performance comparison between a GaAs/mirror/copper thin-film solar cell and a conventional GaAs solar cell with a thick GaAs substrate. The GaAs thin-film solar cell was fabricated by transferring a GaAs solar cell onto a AuGe/Au mirror-coated copper substrate. With the aid of the excellent copper conductor, the thin-film solar cell exhibits significant improvement in both open-circuit voltage and short-circuit current density. The improved current–voltage ($I$– $V$) performance of the thin-film solar cell originates from the following two factors: reduced reverse saturation current by good heat dissipation of copper and enhanced light absorption by the highly reflective AuGe/Au mirror. The role of the mirror can further be verified in the measurement of external quantum efficiency (EQE) response where the thin-film solar cell exhibits a larger EQE response in the wavelength range of 700–900 nm than the conventional GaAs solar cell with the same active absorbing thickness.      

光强和温度对多结太阳电池的影响研究

基于模拟太阳光源的方法,在室内研究了在不同光照强度、不同工作温度下GaAs多结太阳电池的输出特性.通过实验得出:随着光源辐照强度的增加,太阳电池的特性参数:短路电流Isc线性增加,开路电压Voc对数增加,最大输出功率P线性增加,光电转换效率η随聚光比增加到一定程度后减小.对比分析了光强和温度对电池输出特性的影响,数据结...     

Influence of cracks on the local current–voltage parameters of silicon solar cells

The existence of cracks in silicon solar cells can drastically reduce the electrical performance of an individual cell and even of an entire photovoltaic module. An in‐depth understanding of the influence of cracks on solar cells enables therefore calculations of the crack impact and other following effects on module level. This paper shows a detailed analysis of the electrical influence of cracks with two different spatially resolved methods including global and local current–voltage characteristics. The main influence of cracks is an increased recombination current density in the depletion region, which is clearly shown by spatially resolved dark lock‐in thermography measurements with local current–voltage investigation. This increased recombination current density affects further cell parameters such as the efficiency, which is confirmed also by the global current–voltage characteristics. The additionally used ratio image technique based on electroluminescence measurements is in comparison with the local current–voltage method, the more reliable and faster method for the crack detection itself, and allows on cell‐level and module‐level a continuous inspection of cracks. Copyright © 2013 John Wiley & Sons, Ltd.     

不同反射率双面太阳电池背面综合转换效率差异性研究

双面太阳电池是指硅片的正面和反面都可以接受光照并产生光生电压和电流的太阳电池,由于受到结构等各种因素的影响,目前还没有完善的测试方案用于双面太阳电池的完整测试。基于太阳能仿真环境PC1D,采用控制变量的方法来测定电池背面反射率对双面太阳电池综合转换效能的影响,研究了双面电池在不同背面受光条件下的测试结果,得出电池背面背景反射率增大时,双面太阳电池的综合转换效能的变化规律;确定了双面电池合理的测试条件,给出了双面电池科学的测试方案。结论对双面太阳电池的测试和应用具有重要意义。     

Polycrystalline Silicon-Film™ Thin-film Solar Cells: Advanced Products

Thin-film polycrystalline silicon has the potential to achieve the cost reduction and performance improvement necessary for large-scale electricity markets. Reduced cost is achieved by capitalizing on the benefits of thin films grown on low-cost, large-area substrates. Improved efficiency is realized, in spite of reduced material quality, by incorporating enhanced optical absorption and back-surface passivation. The cornerstone of AstroPower's thin-film solar cell technology is the Silicon-Film™ process: a method for the manufacture of solar cell-quality, polycrystalline films of silicon on a variety of low-cost, supporting substrates. Three thin-film solar cell designs, based on this technology, are currently under development. This paper presents the key design features of these three products and briefly reviews the current status of the development of the key technologies that comprise the advanced thin-film solar cell products.     

Solar power generation system for reducing leakage current

This paper proposes a transformer-less multi-level solar power generation system. This solar power generation system is composed of a solar cell array, a boost power converter, an isolation switch set and a full-bridge inverter. A unipolar pulse-width modulation (PWM) strategy is used in the full-bridge inverter to attenuate the output ripple current. Circuit isolation is accomplished by integrating the isolation switch set between the solar cell array and the utility, to suppress the leakage current. The isolation switch set also determines the DC bus voltage for the full-bridge inverter connecting to the solar cell array or the output of the boost power converter. Accordingly, the proposed transformer-less multi-level solar power generation system generates a five-level voltage, and the partial power of the solar cell array is also converted to AC power using only the full-bridge inverter, so the power efficiency is increased. A prototype is developed to validate the performance of the proposed transformer-less multi-level solar power generation system.     

Determination of minority carrier lifetime and effective back surface recombination velocity in BSF silicon solar cells from transient measurements

The method of determining the base lifetime ?B and the effective surface recombination velocity Seff in a BSF solar cell from the transient decay of open-circuit voltage and short-circuit current is extended to include emitter recombinations. If the emitter recombinations in modern Si solar cells are neglected in interpreting the experimental data, the experimental value of Seff is found to be in large error.     

菲涅耳透镜下多结电池表面局部高辐射功率对短路电流的影响

为探索以菲涅耳透镜为聚光器的聚光光伏模组中,多结电池中心局部高辐射功率对短路电流的影响,测量菲涅耳透镜的高亮度光斑直径,并据此分别测试室内不同局部光照面积下和户外不同尺寸透镜下的GaInP/GaInAs/Ge三结电池的短路电流,利用电路网络模型分析实验结果。结果表明,短路电流与局部聚光的面积无关;小尺寸菲涅耳透镜聚焦下,沿光轴电流与辐射功率同步变化;透镜尺寸增大到一定程度,电池中心局部承受过高辐射功率,电流受峰值隧穿电流限制,宏观体现为焦平面处短路电流下降。电池放置在焦平面两侧,均可缓解局部高辐射功率,短路电流最高提升 8.0%。