1 MeV电子辐照下晶格匹配与晶格失配GaInP/GaInAs/Ge三结太阳电池辐射效应研究

对采用MOCVD方法制备的晶格匹配(LM)与晶格失配(UMM)GaInP/GaInAs/Ge三结太阳电池进行了1MeV电子辐射效应研究。结果表明:在电子辐照下,两种电池的I-V特性参数(开路电压Voc,短路电流Isc,最大输出功率Pmax)均发生衰降,且晶格失配电池的I-V特性参数衰降均大于晶格匹配电池。在光谱响应方面,对于顶电池,晶格匹配电池的衰降大于晶格失配电池;而中间电池则前者衰降小于后者;另外,Ge底电池的光谱响应表现特殊,辐照后光谱响应变强。     

Displacement damage analysis and modified electrical equivalent circuit for electron and photon-irradiated silicon solar cells

Solar modules and arrays are the conventional energy resources of space satellites. Outside the earth's atmosphere, solar panels experience abnormal radiation environments and because of incident particles, photovoltaic (PV) parameters degrade. This article tries to analyze the electrical performance of electron and photon-irradiated mono-crystalline silicon (mono-Si) solar cells. PV cells are irradiated by mono-energetic electrons and poly-energetic photons and immediately characterized after the irradiation. The mean degradation of the maximum power (P_max) of silicon solar cells is presented and correlated using the displacement damage dose (D_d) methodology. This method simplifies evaluation of cell performance in space radiation environments and produces a single characteristic curve for P_max degradation. Furthermore, complete analysis of the results revealed that the open-circuit voltage (V_oc) and the filling factor of mono-Si cells did not significantly change during the irradiation and were independent of the radiation type and fluence. Moreover, a new technique is developed that adapts the irradiation-induced effects in a single-cell equivalent electrical circuit and adjusts its elements. The “modified circuit” is capable of modeling the “radiation damage” in the electrical behavior of mono-Si solar cells and simplifies the designing of the compensation circuits.     

Synthesis and characterization of copper doped zinc oxide nanoparticles and its application in energy conversion

Solar cells, in general, perform under light source of solar influx, while the heat energy of solar radiation remains unutilized. Using an aqueous suspension of copper doped zinc oxide nanoparticles in specially-designed electrochemical cells we have observed significant voltage (maximum 632.0 mV) and storage duration (∼47 h) upon thermal excitation. The cells exhibit reasonable energy conversion efficiency (maximum 1.36%). These cells generate voltage even at room temperature (∼30 °C) and the voltage increases gradually with increasing temperature. When the platinum foil separating the two compartments of the electrochemical cell is replaced by a planar lipid membrane, all the parameters e.g., thermovoltage, storage capacity and the energy conversion efficiency increase significantly.     

Interface and bulk properties of Cu(In,Ga)Se2 solar cell with a cracker-ZnS buffer layer

Cu(In,Ga)Se₂ (CIGS) solar cells were fabricated by varying the film thickness of the cracker-ZnS (c-ZnS) buffer layer from 0 nm to 20 nm, and performance was found to depend on c-ZnS film thickness. The best cell efficiency of approximately 8% was obtained from the CIGS solar cell with an 8 nm thick-c-ZnS buffer layer. To investigate the primary factor to determine the cell performance, we utilized the impedance spectroscopy (IS) reflecting interface qualities, and capacitance-voltage (CV) profiling sensitive to bulk properties. In IS results, an equivalent circuit model including the resistance and capacitance was proposed to interpret cell performance, and carrier lifetime was obtained in connection with recombination probability at p-n junction. In CV profiling, the carrier concentration in the CIGS bulk, the depletion width, and the charge distribution related to the defect states along the depth direction were evaluated. The formation mechanism of c-ZnS buffer layer is suggested by measuring the chemical states, which is closely associated with the IS and CV results. The depletion width substantially increased at c-ZnS film thickness more than 15 nm due to the diffusion of Zn atoms toward CIGS layer, resulting in negative influence on cell performance. From this study, we demonstrated that IS and CV profiling are complementary analysis tools for interpretation of the solar cell operation concerning the interface and bulk properties.     

带有蓄热装置的直膨式太阳能热泵系统的模拟研究

介绍了一种带有相变蓄热装置的直膨式太阳能热泵系统。以青岛天气为例,对该系统的蓄热模式进行数值模拟,得出蓄热装置进出口制冷剂的温度、蓄热材料的液相率随时间的变化,结果表明在太阳能辐射量变化时,该系统的蒸发温度维持25℃左右,系统能够稳定运行;对系统热力学性质进行理论计算得出系统在冷凝温度为70℃时,系统的COP能维持在5.3左右,系统能够高效运行。     

Lattice Boltzmann Simulation for Complex Flow in a Solar Wall

In this letter,we present a lattice Boltzmann simulation for complex flow in a solar wall system which includes porous media flow and heat transfer,specifically for solar energy utilization through an unglazed transpired solar air collector(UTC).Besides the lattice Boltzmann equation(LBE) for time evolution of particle distribution function for fluid field,we introduce an analogy,LBE for time evolution of distribution function for temperature.Both temperature fields of fluid(air) and solid(porous media) are modeled.We study the effects of fan velocity,solar radiation intensity,porosity,etc.on the thermal performance of the UTC.In general,our simulation results are in good agreement with what in literature.With the current system setting,both fan velocity and solar radiation intensity have significant effect on the thermal performance of the UTC.However,it is shown that the porosity has negligible effect on the heat collector indicating the current system setting might not be realistic.Further examinations of thermal performance in different UTC systems are ongoing.The results are expected to present in near future.     

Verification of a generalized Planck law for luminescence radiation from silicon solar cells

A generalization of Planck's radiation law based on the principle of detailed balance predicts the emission of luminescence radiation from absorption data for direct transitions in semiconductors. Its validity for indirect transitions is questionable due to the participation of phonons. We have tested the validity for the indirect transitions in Si by measuring absolute values of the emission intensity from Si solar cells under forward bias at room temperature and find good agreement with theoretical predictions based on existing absorption data. The generalized Planck law, thus verified for the indirect transitions in Si, allows to determine the performance of solar cell materials from measuring the absolute intensity of their emission of luminescence radiation when irradiated by the sun.     

聚光型光伏电池冷却热管蒸发端的数值模拟

针对碟式聚光型太阳能光伏电池效率受温度制约的问题,采用两相闭式热虹吸管(重力热管)散热的方式,工质采用水.热管的蒸发端与聚光太阳能电池接触,其温度场对电池性能和热管效率影响显著.通过FLuENT建立了蒸发端底部的数学模型,计算过程中考虑热流密度、蒸汽饱和温度以及充液量对蒸发端性能的影响.计算结果表明,在聚光倍数为140...     

Estimation of the required collector area of a solar assisted heat pump

The solar assisted heat pump represents a method of increasing the heat pump COP by transferring solar radiation heat to the heat pump evaporator. In this paper a method of calculating the minimum design limit for the collector area based on the second law efficiency is introduced by using a set of experimental data on a certain design of a solar assisted heat pump system during winter time. A comparative study is made between the actual and ideal conditions, and a minimum required area of the collector is suggested.     

Radiation effects in silicon solar cells

Silicon solar cells have been utilized as the principal source of electrical energy for space satellites during the past decade. Despite the reliability of these photovoltaic devices, degradation of their power output by charged particle radiation in the earth's geomagnetic field has continued to be the primary problem for their use on flights of long-duration. A study of radiation damage induced by 1 MeV electrons in a variety of current silicon solar cell types has been conducted as a function of dopant impurity and resistivity of the base region. A companion study of radiation damage induced by nominal 0.2 MeV protons was performed in solar cells with coverslips having small cell areas exposed alongside the coverslip. The photovoltaic current-voltage characteristics were measured under a solar simulator emitting 140mW/cm² at air mass zero. Irradiations were performed at room temperature to fluences of 1 × 10¹⁵ e/cm² and 1 × 10¹⁵ p/cm². The efficiency of 10 ohm-cm cells after large fluences was superior to cells of 2 ohm-cm base resistivity. No significant differences were observed between boron- and aluminum-doped cells. Solar cell exposure to low energy Protons resulted in an 8 per cent loss in power at a fluence of 1 × 10¹⁴ p/cm² when as little as 2 per cent of the solar cell surface was left unshielded.     

30m~2槽式太阳能集热器性能模拟研究

本文针对30 m~2槽式太阳能集热试验装置,对太阳能集热器的性能进行了模拟。分析了太阳能集热器光热转化过程,建立了太阳能能量转换与传递模型,并开发了模拟计算程序,研究了集热器关键结构参数和运行参数对集热性能的影响规律。具体考察了太阳辐照强度、工质流量、环境风速、吸热管管径等对集热效率的影响。结果表明:太阳能集热器的集热效率随太阳辐照强度的增加而增大,随工质流量的增加而增大,存在最佳的吸热管管径使得集热效率最大。研究结果将为太阳能集热器的设计提供参考依据。     

直膨式太阳能热泵热水器的实验研究

建立了直膨式太阳能热泵热水器实验样机,该样机采用裸板式太阳能集热器作为蒸发器。在室内模拟光源(0～1000W/m2)下,对该热水器进行了性能测试,得出热水平均加热功率为1.04 kW,热泵平均COP为4.18。通过对实验数据加以整理和分析,得出了热水温度、集热/蒸发板温度、热水加热功率及热泵COP随太阳辐射强度及运行时间的变化规律,并提出了热泵COP的改善措施。     

Effect of gamma and beta radiation on I–V characterization of the solar cell panel

ABSTRACT

Optoelectronic devices, widely used in high energy and nuclear physics applications, suffer severe radiation damage that leads to degradations in its efficiency. In this paper, the influence of gamma radiation (¹³⁷Ce source) and beta radiation (⁹⁰Sr source) on the photoelectric parameters of the Si solar cell, based on the I–V characterization at different irradiation exposer, has been studied. The penetrating radiation produces defects in the base material, may be activated during its lifetime, becoming traps for electron–hole pairs produced optically and, this will, decrease the efficiency of the solar cell. The main objective of the paper is to study and measure changes in the I–V characteristics of solar cells, such as efficiency, maximum current, maximum power, and efficiency, due to the exposure of solar systems to different doses of γ and β irradiations.     

氧化随机织构硅表面对单晶硅太阳电池性能的影响研究

热氧化生长的SiO\-2 薄膜经常在高效单晶硅太阳电池中被用作扩散掩膜,化学镀掩膜,钝化层或者基本的减反射层.在这些高效太阳电池中,经常使用碱性溶液对单晶硅表面进行处理,得到随机分布的正金字塔结构的织绒表面,减少表面的光反射.表面氧化后的正金字塔太阳电池暗反向电流-电压呈现"软击穿"现象,并联电阻明显下降.研究结果表明引起这些现象的原因在于氧化正金字塔表面会导致在体内形成位错型缺陷,这些缺陷能够贯穿整个pn 结,导致太阳电池的并联电阻下降,同时载流子在位错型缺陷在能隙中引入的能级处发生复合,导致空间电荷区 关键词： 热氧化 随机织构 位错 太阳电池     

低温容器高真空多层绝热性能分析

高真空多层绝热性能对于低温容器的应用与安全至关重要。文中依据逐层导热计算模型,对高真空多层绝热低温容器的气体导热、间隔材料的固体导热和反射屏的辐射换热进行了分析计算,给出了多层绝热层中每一层的温度分布情况,气体导热、固体导热及辐射换热所占的比例,换热系数随层数的变化情况,以及真空度对绝热性能的影响,为提高高真空多层绝热性能提供了理论依据。     

Evaluation and prediction of the degradation of space Si solar cells induced by a low-earth-orbit radiation environment

Space-graded silicon solar cells are evaluated by 1 MeV and 2 MeV electron-irradiation. The mean degradation of the maximum power (P_max) is presented and analyzed. The degradation at both electron energies has been correlated with the displacement damage dose (D_d). A good linearity between the electron D_d and the mean P_max degradation is obtained. The concept of D_d has also been used to predict the Si solar cell response in a low-earth-orbit (Altitude 799 km, Inclination 99^o) radiation environment, considering the shielded effect of a 120 μ m-thick silica coverglass on reducing the radiation. Compared with the on-orbit data from a Si solar array of a Chinese satellite (duration from April 2007 to July 2010), a good match can be found between the on-orbit data and the predicted results using D_d methodology, indicating the method is appropriate for evaluating the radiation damage of the solar cells, and also to provide a new technique for studying radiation effects on the optoelectronic detectors used in many high energy physics applications, where harsh radiation environments produce damage in optoelectronic device materials.     

电子束蒸发沉积Ir膜真空紫外反射特性

Ir是一种重要的真空紫外反射材料,在太阳物理、宇宙物理、生命科学、大气物理、同步辐射等方面有着十分重要的应用.对电子束蒸发沉积Ir膜在真空紫外波段的反射特性进行了系统的理论和实验研究.根据吸收材料基底上单层金属膜数学计算模型,对不同基片上各种厚度的Ir膜真空紫外反射率进行了优化计算.根据计算和前期实验结果,采用电子束蒸发方法,在石英、K9玻璃基片上沉积了不同厚度的Ir膜,在入射波长120 nm处获得了近30%正入射反射率,对应的Ir膜厚度为12 nm.过厚或过薄均不利于Ir膜反射率的提高.经退火处理后,Ir膜中张应力有所释放但并未消除,同时晶粒平均尺寸显著增大,反射率下降.     

Ti0.33WO3电子结构和太阳辐射屏蔽性能第一性原理研究

节能减排已成为当今社会发展的主题,对节约能源、提高太阳能的高效综合利用的新型窗用透明隔热材料的理论设计和研究尤其重要.本文采用基于密度泛函理论的计算方法,研究了六方相三氧化钨Ti掺杂前、后的晶格参数、电子能带结构、形成能和光学性质.研究结果表明,Ti掺杂后晶格体积增大,系统能量降为负值,体系具有更好的稳定性;掺杂后电子能带结构发生很大的变化,但材料仍保持n型电导率;随之,其光学性质也发生改变,掺杂前h-WO3无近红外吸收性能,掺杂后的Ti0.33WO3具有很强的近红外吸收性能.在此基础上研究了Ti掺杂h-WO3前、后的太阳辐射屏蔽性能,掺杂前无太阳辐射屏蔽性能;掺杂后的Ti0.33WO3薄膜具有可见光高透明、近红外屏蔽的性能.计算结果为Ti掺杂h-WO3在窗用透明隔热材料方面的研究提供了理论依据.     

Effects of electron radiation on shielded space and triple-junction GaAs solar cells

The displacement damage dose methodology for analysing and modelling the performance of triple-junction InGaP₂/GaAs/Ge solar cells in an electron radiation environment is presented. Degradations at different electron energies are correlated with displacement damage dose (D_\rm d). One particular electron radiation environment, relative to a geosynchronous earth orbit (GEO), is chosen to calculate the total D_\rm d behind the different thicknesses coverglasses to predict the performance degradation at the end of the 15-year mission.