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The heterojunction (HJ) solar cell is one of the best possible options to upgrade the conventional single homo-junction c-Si solar cell. In this work, a single HJ solar cell based on crystalline silicon (c-Si) wafer with zinc oxide (ZnO) is designed to reduce the loss of power conversion owing to the reflection of incident photons by the top surface of silicon. A PC1D simulation is used to evaluate the optimum numerical value of key photovoltaic parameters for HJ-based c-Si solar cells. The average reflectance for ZnO/Si HJ-based c-Si is 7.65% in the wavelength range of 400-1000 nm. The highest efficiency (η = 24.8%) of the ZnO/Si HJ-based c-Si solar is obtained with a 400 μm base thickness, 20 μm emitter thickness, doping concentration of 1.1 × 1017 cm−3 in the base and a doping concentration of 5.1 x 1016 cm−3 in the emitter. The proposed ZnO/Si HJ-based c-Si solar cell with high efficiency would be one of the best possible alternative HJ device to the conventional single homo-junction c-Si solar cell.

Pure and Mg-doped manganese oxide thin films were synthesized on heated glass substrates using the spray pyrolysis technique. The surface chemical composition was investigated by the use of X-ray photoelectron spectroscopy (XPS). Structural and morphological properties were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscopy (AFM). Optical properties were characterized by UV-visible spectroscopy. XPS spectra showed typical Mn (2p3/2), (2p1/2) and O (1s) peaks of Mn3O4 with a slight shift attributed to the formation of different chemical states of manganese. XRD analysis revealed the tetragonal phase of Mn3O4 with a preferred (211) growth orientation that improved with Mg-doping, likewise, grain size is observed to increase with the Mg doping. SEM images of Mn3O4 films showed rough surfaces composed of uniformly distributed nanograins whose size decreases with the Mg-doping. The manganese oxide films surface observed in AFM show a textured, rough and porous surface. The combination of transmittance and absorption data in the UV-visible range allowed determining the energy values of the Eg band gap (1.5–2.5 eV). The decrease of the band gap with the Mg-doping increase is attributed to the influence of the greater size of the Mg2+ ion in the manganese oxide lattice.

The total monthly average of daily radiation on a horizontal surface at the site of Oran (35.38 deg N, 0.37 deg W) is achieved by applying two models. We present a comparison between the first one which is a regression equation of the Angstrom type and the second model, developed by the present authors: Some modifications were recommended using relative humidity as the input meteorological parameter) and longitude, latitude, and altitude as the astronomical parameters. The process of examining similarities is made using root mean square error (RMSE), the mean bias error (MBE), mean absolute error (MAE), and mean absolute percentage error (MAPE). This comparison shows that the second model is closer to the experimental values of the Angstrom model.

This paper analyses the necessity of PLL (Phase Locked Loop-controlled) circuit for series resonant inverter in high frequency induction heating power supply. We were interested in modeling and simulation of an inverter with SIT (Static Induction Transistor) functioning at resonance and intended for the induction heating of high frequency ferromagnetic cylindrical piece. During the heating of the ferromagnetic piece, the resistive and inductive equivalent parameters of the inductor-load varied with the temperature. Thus it became necessary to vary the frequency of operation of the inverter to maintain the resonance. An order by PLL was employed for the continuation of the frequency resonance. The model simulation of the resonant inverter series model was established in MATLAB/Simulink. The simulation results indicate that this circuit can keep the power-factor angle just changing within an acceptable range. It can guarantee the inverter to operate in the small-inductive condition, reduce the switching losses of SITs, and enhance the security of the power supply. Also, the obtained results show that the proposed electrical circuit track perfectly the resonance frequency even around the Curie temperature of the material despite the large variation of the frequency near the Curie point.