Solar energy usage is thriving day by day. These solar panels are installed to absorb solar energy and produce electrical energy. As a result, the efficiency of solar panels depends on different environmental factors, namely, air temperature, dust (aerosols and accumulated dust), and solar incidence, and photovoltaic panel angles. The effects of real conditions factors on power and efficiency of photovoltaic panels are studied in this paper through testing the panel in real environmental tests. To study the mentioned parameters precisely, two panels with different angles are used. The case study is regarding a region of Tehran, Iran, in summer and winter seasons. The results show that panel efficiency during winter is higher than summer due to air temperature decrement. It is discovered that among air pollutants, Al and Fe have the most share in polluting the air that affect the photovoltaic efficiency. Moreover, measuring the accumulated dust on the panels shows more amount in winter in comparison with summer. The important point in studying the effect of tilt angle is that inconformity between solar incidence and photovoltaic panel angles would result in solar radiation absorption and eventually panel efficiency loss and also, photovoltaic panel installation angle would affect the amount of dust deposited on its surface.

The reliability of power electronic devices and components is very important to manufacturers. In recent years, many researchers have conducted reliability assessments of power electronic devices, yet the reliability of numerous circuits used widely has not been evaluated. This paper presents a comprehensive reliability evaluation of fundamental multilevel inverters. The reliability of the multilevel inverters is analyzed by calculating the mean time to failure for each component. The calculation was performed by two methods (approximate and exact) to achieve better comparisons. The approximate method is similar to the parts count method used in MIL-HDBK-217 reliability standard, and the exact method exhibits the parts stress method. In the exact method, due to the direct relationship between component failure and temperature, we used Matlab Simulink to determine power losses in diodes and switches taking into account the temperature factor. The results determined by the approximate method showed that the three-level cascade H-bridge was the most reliable of the inverters considered. Although the exact method validates those results, and shows that cascade H-bridge (CHB) had a longer lifespan, but the calculated values are different. Therefore, using different approaches for evaluating reliability results in different outcomes.

The Vernier permanent magnet machine is a high-torque, low-speed system suitable for direct-drive applications such as in-wheel electrical machines and wind generation turbines. In this paper, specific critical parameters of the electrical machine for auxiliary tooth and slot are investigated in different conditions. It should be noted that all the models are fully optimized and compared under the same condition by FEA analysis. The results illustrate that the stator with α ≠ β = θ is the best choice for stator split pole. Also, the concentrated winding is wound around the main stator tooth and the magnets mounted on the rotor surface. Besides, all essential characteristics for an electric machine such as torque, cogging torque, power factor, and efficiency are investigated. Furthermore, many basic formulas for designing a Vernier machine are proposed. This comparison helps designers choose the best combination among α, β, and θ in the split-pole structures. There is a nomenclature to organize this manuscript for the reader. It should be noted that all the figures are baked by ANSYS Electronics Maxwell version 19.0. Moreover, all of them are modified by Origin software to show with high quality.