Experimental Analysis of Conditions Based Variations of Characteristics and Parameters of Photovoltaic Modules

This paper presents an experimental determination of the main and advanced characteristics of photovoltaic (solar-PV) modules as affected by variations in the solar irradiance and temperature. In addition, the effects of connecting modules in series, and in parallel are inspected. The measured main characteristics are the current/voltage (IV), and power/voltage (PV) relations, while the advanced characteristics include the form factor (FF), shunt resistance (Rsh), series resistance (Rs), characteristic resistance (Rch), and efficiency (). The impacts of the various levels of partial shading on the performance of the modules are also presented. Two identical 10 Wp modules are used in the tests. The sun’s energy is simulated using two lighting sources: One 1 kW halogen floodlight and four 100 W incandescent lamps. These light sources offer spectral which is very close to that of the black body radiation; however, they provide a lower color temperature in comparison with the sun. Therefore, they closely match the requirements of the IEC 60904-9 Edition2 and ASTM E927-10 standards of solar simulators. The electrical load is represented using two wound rheostats of 1200, and 500. The temperature is measured by a remote temperature sensor, while the electrical variables are measured using digital multi-meters. For cost reduction, the solar irradiance is estimated based on the linear relation between the short-circuit current, and the solar irradiance. The results are presented within the main text, and summarized in the conclusions section. It is found that the parameters such as Rs, Rsh, Rch, FF, and  are not constant, but they are highly dependent on the variations in the irradiance, and the temperature. The salient conclusion is that the standard equivalent circuit model of solar-PV modules that includes constant parameters needs to be significantly enhanced by considering the variations of the circuit parameters as affected by the variations in the solar irradiance and temperature.<br>

本研究通过实验测定了受太阳辐照度与温度变化影响的光伏（photovoltaic，solar-PV）组件的基础与进阶性能特性。此外，本研究还考察了组件串、并联连接所带来的影响。本次实验测得的基础特性包括电流-电压（IV）与功率-电压（PV）关系曲线；进阶特性则涵盖填充因子（FF）、分流电阻（Rsh）、串联电阻（Rs）、特性电阻（Rch）以及效率（η）。此外，本研究还分析了不同程度的局部遮阴对组件性能的影响。实验采用两块规格一致的10峰瓦（Wp）光伏组件。本研究采用两种光源模拟太阳光能：一台1千瓦卤素泛光灯与四盏100瓦白炽灯。这两种光源的光谱分布与黑体辐射极为接近，但相较于太阳光，其色温更低。因此，该光源完全符合太阳能模拟器的IEC 60904-9 第2版与ASTM E927-10标准的要求。实验采用两台绕线变阻器作为电学负载，阻值分别为1200欧姆与500欧姆。温度通过远程温度传感器进行采集，电学变量则采用数字万用表进行测量。为降低实验成本，本研究基于短路电流与太阳辐照度之间的线性关系对太阳辐照度进行估算。实验结果已在正文中详述，并在结论部分进行了总结归纳。研究发现，Rs、Rsh、Rch、FF以及η等参数并非恒定值，而是高度依赖于辐照度与温度的变化。本研究的核心结论为：传统的恒定参数光伏组件等效电路模型亟需得到大幅改进，需将太阳辐照度与温度变化对电路参数的影响纳入考量范围。