不规则太阳电池临近空间发电模型构建与分析

临近空间长航时飞行器（平流层飞艇、太阳能飞机、高空科学气球等）是目前高空平台（HAPS）的一种发展趋势。目前临近空间长航时飞行器的能量来源主要是太阳电池,由于飞行器形状和体积不同,太阳电池安装位置和面积也不同。飞行器有效铺装面积有限,为了实现能量平衡,因需要铺装更大面积,会遇到不规则形状铺装的情形,但此时的发电预测计算过程比较复杂且速度较慢。该文提出一种基于太阳电池之间关系的发电模型,实现任意单块太阳电池快速预测光伏阵列发电功率。针对现有飞行器不规则铺设太阳电池的进行仿真分析,结果表明,该模型能够准确预测其发电能力,并解决了不规则太阳电池发电能力的准确预测计算过程复杂和速度较慢的问题,修正后的模型在计算用时效率上最多可减少50%。     

在户外条件下测量晶体硅组件最大功率的不确定度分析

依据地面用晶体硅光伏组件设计鉴定和定型标准(IEC61215-2005)的要求,在户外自然光条件下,对地面用晶体硅光伏组件的I-V特性进行了测量;依据光伏器件实测特性的温度和辐照度修正方法标准(IEC60891-2009)对测得的电压、电流及最大功率进行修正,使其结果能回推到标准测试条件(STC)下。分析了产生测量不确定度的因素。通过计算得出回推到标准测试条件下的电压、电流及最大功率的标准不确定度和扩展不确定度。     

南极中山站30 kW光伏发电系统工作特性研究

研究南极中山站地区太阳辐照度和环境温度的联合分布情况,确定极端环境条件;建立不同辐照度和温度条件下光伏电池I-V特性分析模型,分析极端条件对电池发电特性的影响;研究确定2种30 kW光伏发电阵列方案,并对光伏阵列的发电性能进行仿真分析。研究结果:极区环境对光伏组件的发电特性有较大影响,在倾角、辐照度和环境温度等因素影响下,光伏组件的开路电压、最大功率电压能够增大16.9%,短路电流、最大功率电流增大31%,瞬间最大功率可能增大50.2%。     

利用光谱响应研究太阳电池基区少数载流子扩散长度

针对已有的晶体硅太阳电池基区少数载流子的扩散长度测量模型和测试方法中存在的不足,建立利用光谱响应研究硅太阳电池基区少数载流子的扩散长度的模型,该模型考虑了n+pp+型晶体硅太阳电池背面高低结势垒的影响,对基区少数载流子扩散长度的测量模型进行修正。根据硅太阳电池在900~950 nm的长波光谱响应测试结果,并利用该修正模型得到少数载流子在基区的扩散长度。所得结果与PC1 D模拟结果进行比较,两者相近。     

计及表面纹理结构的晶硅太阳电池温度预测模型

根据现代太阳电池工艺,提出一种计及太阳电池表面晶硅纹理结构的光热特性耦合温度预测模型。首先,根据面板几何位置和时间信息对入射光进行等效折算,通过离散坐标辐射传输模型得到波长分布;然后,以光路概率分布计算汇总硅结构反射路径,得到波长对应光学系数;最后,通过能量平衡数值求解得到太阳电池预测温度变化。通过仿真验证和实验数据对比,该模型的预测精度较平面近似温度模型预测精度更高,可用于短时或中长时的太阳电池温度变化预测。     

晶体硅太阳电池串联内阻的函数形式

在已知的四种电阻函数形式中，通过理论推导并结合晶体硅太阳电池功率随着温度上升而下降的实验事实，理论证明晶体硅太阳电池串联内阻具有正温度系数半导体型电阻的数学表述形式。利用该数学形式对实测内阻数据进行拟合，结果令人满意。     

一个新的太阳电池显式模型以预测在任何太阳辐照度和温度时的I-V

采用求解满足实验结果的微分方程，建立一个三参数的显函数模型。经过22条实验数据的验证肯定该模型的正确性。更好的结果是该工作成功地发展出次级模型即模型参数同太阳辐照度及温度的定量关系，从而实现用太阳辐照度和温度预测太阳电池的I-V。     

基于多传感器信息融合的太阳电池动态建模

为获取运动状态下太阳电池输出特性,提出一种基于多传感器信息融合的太阳电池动态建模方法。基于多传感器信息融合测量模型、欧式空间旋转理论、光照强度与太阳电池空间位置关系和太阳电池数学模型及其参数与光照强度之间耦合关系,构建太阳电池动态模型得到其动态输出特性。通过SIMPACK及Matlab/Simulink仿真软件建立太阳电池动态发电仿真平台验证了方法的有效性。结果表明,载体的运动明显影响了太阳电池输出特性,且在太阳电池输出最大功率点处的功率最大减少了18.038%。     

考虑多变量因素影响的光伏PEM制氢系统建模与分析

针对复杂工况对光伏制氢系统性能产生不确定性的影响,提出考虑多变量因素影响的光伏制氢系统模型,探索辐照度、温度、膜厚、压力等因素对光伏质子交换膜（PEM）制氢系统的影响。系统首先建立考虑辐照度、温度、膜厚、压力等因素影响的光伏-质子交换膜电解槽-氢储罐的光伏制氢模型,之后对系统进行定量计算和定性分析,并依据实际光伏数据进行实验验证。结果表明,在额定功率范围内,太阳电池输出电流和功率随辐照度的增加而增大,随温度的升高而降低。质子交换膜电解槽电压随辐照度、膜厚、压力的增加而增大,随温度的升高而减小。太阳电池输出功率、质子交换膜电解槽电压的变化趋势与辐照度变化趋势具有一致性。最终计算得到太阳电池系统、质子交换膜电解槽系统和总系统效率分别为16.8%、72.2%和12.1%。     

基于GA-GRU神经网络的光伏MPPT算法

针对外界环境因素快速变化时，光伏发电系统难以保持在最大功率点输出的问题，提出遗传算法与GRU神经网络相结合的最大功率跟踪算法（GA-GRU-MPPT）。该算法在构建的最大功率点预测模型基础上，采用遗传算法对GRU神经网络的参数进行优化。考虑到数据的关联性，将前一时刻的太阳电池温度、太阳辐照度、最大功率点电压及当前时刻的太阳电池温度和太阳辐照度作为预测模型的输入变量，输出为当前时刻的最大功率点电压。针对3种不同气候情形的仿真结果表明，该算法跟踪精度可达99%，能显著提高光伏系统的能量转换效率。     

Performance study of solar cell arrays based on a Trough Concentrating Photovoltaic/Thermal system

The performances of solar cell arrays based on a Trough Concentrating Photovoltaic/Thermal (TCPV/T) system have been studied via both experiment and theoretical calculation. The I–V characteristics of the solar cell arrays and the output performances of the TCPV/T system demonstrated that among the investigated four types of solar cell arrays, the triple junction GaAs cells possessed good performance characteristics and the polysilicon cells exhibited poor performance characteristics under concentrating conditions. The optimum concentration ratios for the single crystalline silicon cell, the Super cells and the GaAs cells were also studied by experiments. The optimum concentration ratios for the single crystalline silicon cells and Super cells were 4.23 and 8.46 respectively, and the triple junction GaAs cells could work well at higher concentration ratio. Besides, some theoretical calculations and experiments were performed to explore the influences of the series resistances and the working temperature. When the series resistances R_s changed from 0 Ω to 1 Ω, the maximum power P_m of the single crystalline silicon, the polycrystalline silicon, the Super cell and the GaAs cell arrays decreased by 67.78%, 74.93%, 77.30% and 58.07% respectively. When the cell temperature increased by 1 K, the short circuit current of the four types of solar cell arrays decreased by 0.11818 A, 0.05364 A, 0.01387 A and 0.00215 A respectively. The research results demonstrated that the output performance of the solar cell arrays with lower series resistance was better and the working temperature had a negative impact on the current under concentration. In addition, solar irradiation intensity had certain effects on the solar cell’s performance. For the crystalline silicon solar cell arrays, when the solar direct radiation exceeded a certain value, the I–V curves almost became a straight line and the output performances decreased due to the high series resistance leading to the high power loss. For the triple junction GaAs solar cell array, its performance was always excellent.     

非晶硅与晶硅太阳电池在太阳能光伏发电应用中热性能的研究

对在北京地区屋面上固定角度安装(目前光伏发电应用中最常见的安装形式)的非晶硅和多晶硅太阳电池组件进行了近二年的数据采集,纪录了北京地区温度数据和太阳电池阵列的实际发电量,分析了它们各自的特点,为用户更为关心的户外使用情况提供了参考依据;认为如果仅从温度特性考虑,是否采用非晶硅替代晶体硅电池在不同地区应有不同考虑,如果再考虑到人们普遍认为的非晶硅电池没有解决的稳定性问题,表面玻璃的非钢化、效率低等其它问题,非晶硅的使用应慎重,不应盲从.同时在使用中不论何种电池都不应忽视组件的通风问题.     

一种计算空间电池阵输出的新方法

在求解太阳电池阵输出的方法中,有的方法能求出输出功率,但不能求出输出电流、输出电压;有的虽能求出输出电流、电压,但未考虑太阳辐射光强对它们的影响。本文提出一种新的方法,能求出太阳电池阵工作温度、输出电流和输出电压,并考虑了太阳辐射光强的影响。该方法包括一个I-V特征关系式和一个能量平衡模型。光强和太阳电池的温度是I-V特征关系式中的变量。能量平衡模型是在稳态、忽略太阳电池的热容条件下建立的。用该种方法分析了安装在太阳能飞机上的太阳能电池阵。     

Space solar cells—tradeoff analysis

This paper summarizes the study that had the objective to tradeoff space solar cells and solar array designs to determine the best choice of solar cell and array technology that would be more beneficial in terms of mass, area and cost for different types of space missions. Space solar cells, which are commercially now available in the market and to be available in the near future, were considered for this trade study. Four solar array designs: rigid, flexible, thin film flexible and concentrator solar arrays were considered for assessment. Performance of the solar cells along with solar array designs were studied for two types of space missions: geo synchronous orbit (GEO) and low earth orbit (LEO) spacecraft. The Solar array designs assumed were to provide 15 kW power for 15 years mission life in GEO and 5 kW power for 5 years mission life in LEO altitudes. To perform tradeoff analysis a spread sheet model was developed that calculates the size, mass and estimates the cost of solar arrays based on different solar cell and array technologies for given set of mission requirements. Comparative performance metrics (W/kg, W/m², kg/m², and $/W) were calculated for all solar arrays studied and compared, at the solar array subsystem level and also at the spacecraft system level. The trade analysis results show that high-efficiency multijunction solar cells bring lot of cost advantages for both types of missions. The trade study also show that thin film solar cells with moderate efficiency with ultra lightweight flexible array design may become competitive with well-established single crystalline solar cell technologies in the future.     

Ray-trace simulation of light trapping in silicon solar cell with texture structures

We investigated the light trapping effect in a solar cell. We performed ray-tracing simulation for a light trapping structure in a silicon crystalline solar cell. By comparing theoretical and experimental values, the reliability of a simulation technique was evaluated. Using this simulation technique, we evaluated the light trapping effect in the silicon crystalline solar cell and glass with a V-shaped texture. Furthermore, we investigated the light trapping effect in a silicon thin film solar cell. In a silicon thin film with a thickness of 20 μm deposited on V-shaped glass, reflectivity which is comparable to that in a pyramidal texture structure was obtained. We concluded that the simulation technique used in this work is very effective for optimization of the structure in the enhancement of the light trapping effect.     

Modeling the thermal absorption factor of photovoltaic/thermal combi-panels

In a photovoltaic/thermal combi-panel solar cells generate electricity while residual heat is extracted to be used for tap water heating or room heating. In such a panel the entire solar spectrum can be used in principle. Unfortunately long wavelength solar irradiance is poorly absorbed by the semiconductor material in standard solar cells. A computer model was developed to determine the thermal absorption factor of crystalline silicon solar cells. It was found that for a standard untextured solar cell with a silver back contact a relatively large amount of long wavelength irradiance is lost by reflection resulting in an absorption factor of only 74%. The model was then used to investigate ways to increase this absorption factor. One way is absorbing long wavelength irradiance in a second absorber behind a semi-transparent solar cell. According to the model this will increase the total absorption factor to 87%. The second way is to absorb irradiance in the back contact of the solar cell by using rough interfaces in combination with a non-standard metal as back contact. Theoretically the absorption factor can then be increased to 85%.     

基于S-V特性分析的晶硅光伏组件阴影遮障诊断

针对广泛使用的晶硅光伏组件,通过Simulink建立太阳电池双二极管精确仿真模型,对实际应用中最常见的光伏组件阴影遮挡故障进行多种工况的仿真验证。根据I-V曲线拐点、台阶、曲线下积分面积（S）下降的特征,提出一种基于S-V曲线特性的光伏组件阴影遮挡故障的在线诊断方法。该方法建立S-V曲线,根据S-V曲线分叉点位置可判断光伏组件遮挡情况,通过整体积分面积进而判断遮挡比例。对温度、辐照度进行折算,使该方法在全工况下适用。结合光伏组件功率优化器验证该诊断方法有较高的准确率,并且可准确地判断阴影遮挡面积,具有很高的实际应用价值。     

Adaptive neuro-fuzzy inference system-based maximum power point tracking of solar PV modules for fast varying solar radiations

This paper analyses the operation of an adaptive neuro-fuzzy inference system (ANFIS)-based maximum power point tracking (MPPT) for solar photovoltaic (SPV) energy generation system. The MPPT works on the principle of adjusting the voltage of the SPV modules by changing the duty ratio of the boost converter. The duty ratio of the boost converter is calculated for a given solar irradiance and temperature condition by a closed-loop control scheme. The ANFIS is trained to generate maximum power corresponding to the given solar irradiance level and temperature. The response of the ANFIS-based control system is highly precise and offers an extremely fast response. The response time is seen as nearly 1 ms for fast varying cell temperature and 6 ms for fast varying solar irradiance. The simulation is done for fast-changing solar irradiance and temperature conditions. The response of the proposed controller is also presented.     

The absorption factor of crystalline silicon PV cells: A numerical and experimental study

The absorption factor of a PV cell is defined as the fraction of incident solar irradiance that is absorbed by the cell. This absorption factor is one of the major parameters determining the cell temperature under operational conditions. Experimentally the absorption factor can be derived from reflection and transmission measurements. The spectral reflection and transmission factors were measured for a set of crystalline silicon (c-Si) samples with a gradually increasing complexity. The experimental results agree very well with the results from a 2D numerical model that was developed. It was found that the AM1.5 absorption factor of a typical encapsulated c-Si photovoltaic cell is as high as 90.5%. Insight was gained in the cell parameters that influence this absorption factor. The presence of texture at the front of the c-Si wafer of sufficient steepness is essential to achieve such a high absorption factor. Sub-bandgap solar irradiance is mainly absorbed in the very thin emitter by means of free-carrier absorption. By minimizing reflective losses over the entire solar spectrum, the AM1.5 absorption of c-Si cells can theoretically be increased to 93.0%. The effect on the annual yield of PV and PV/thermal systems is quantified.