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The current-voltage ( I-V) equation in equivalent circuit model (ECM) of photovoltaic (PV) module is implicit and the dependence of model parameters on environmental conditions is uncertain, which causes inconvenience in output performance prediction. In this paper, a novel method based on power-law model (PLM) is proposed to predict the I-V characteristics and output power of PV modules under varying operating conditions. The irradiance and temperature dependence on shape parameters in PLM are deduced from the irradiance and temperature dependence on SC, OC and MPP analytically and investigated thoroughly. The relationship between parameters in PLM and manufacturer datasheet information are established. Due to inherent simplicity and explicit expression of PLM, the proposed method predicts the I-V characteristics and output power without using any iterative process, which reduces the computational complexity. The proposed method is validated by different types PV modules and under a wide range of environmental conditions. Comparing with traditional methods based on ECM, the proposed method has better agreements with experimental results in all irradiance and temperature intervals. The accuracy and effectiveness are verified both in short-term and long-term output power prediction. The proposed method is simple and suitable to predict the actual output properties of PV modules under varying operating conditions.

In traditional methods, electrical property estimation of photovoltaic (PV) modules is achieved through two steps. First, a certain condition (usually standard testing condition, STC) is selected as the reference condition, and the physical parameters under the reference condition are extracted from current–voltage data points. Second, physical parameters under varying operating conditions are obtained by transforming equations, and the electrical properties of the PV modules are estimated. In this paper, the influence of different reference conditions on the accuracy of performance estimation is studied. The estimation results using different reference conditions are compared to obtain the error distribution pattern, which has essential reference significance for the selection of reference conditions in practical applications. In addition, a method of the selecting reference condition is proposed. A new objective function is proposed by considering three key operating points for each I–V curve under different operating conditions, which balances accuracy and computational complexity. A large amount of experimental data for different types of PV modules are used to validate the effectiveness and accuracy of the proposed method. In comparison with the traditional methods using STC as the reference condition and existing method in Matlab/Simulink, the results obtained by the proposed method exhibit better accuracy. It can be further used to estimate the output power of PV system under varying operating conditions.

With the development of hydrogen energy, containerized hydrogen fuel cell systems are being used in distributed energy-supply systems. Hydrogen pipelines and electronic equipment of fuel cell containers can trigger hydrogen-explosion accidents. In the present study, Computational Fluid Dynamics (CFD) software was used to calculate the affected areas of hydrogen fuel cell container-explosion accidents with and without protective walls. The protective effects were studied for protective walls at various distances and heights. The results show that strategically placing protective walls can effectively block the propagation of shock waves and flames. However, the protective wall has a limited effect on the reduction of overpressure and temperature behind the wall when the protective wall is insufficiently high. Reflected explosion shock waves and flames will cause damage to the area inside the wall when the protective wall is too close to the container. In this study, a protective wall that is 5 m away from the container and 3 m high can effectively protect the area behind the wall and prevent damage to the container due to the reflection of shock waves and flame. This paper presents a suitable protective wall setting scheme for hydrogen fuel cell containers.