In order to improve the photovoltaic (PV) production, the researchers are interested in developing new methods to reach the Maximum Power Point (MPP) produced by the photovoltaic field to be injected into the utility grid. This article describes a new method called the Optimized Steepest Gradient Method (OSGM), it is based on the first (gradient) and second order (hessian) derivatives of the power function in order to find the best variation of the voltage (Vpv) with the calculation of the optimal step allowing the convergence to the tension value (Vref) which ensures the MPP. The mathematical model has been developed and implemented under Matlab/Simulink environment. To analyze Maximum Power Point Tracking (MPPT) algorithm performances, time response, oscillation, overshoot and stability are taken into account. The OSGM is implemented and compared to three others algorithms (one of these algorithm is the ANFIS proposed in previous work). Performances obtained by the proposed algorithm offer faster response, less oscillations around MPP and a low energy loss. In addition, numerical computation of the gradient and the hessian of the power function allow bypassing modeling inaccuracies.
In this work, titanium dioxide (TiO 2) thin films have been deposited on glass and monocrystalline silicon by Atmospheric Pressure Chemical Vapor Deposition (APCVD) technique using titanium tetrachloride TiCl 4 as precursor. The structural, electrical and optical properties of the prepared TiO 2 thin films were evaluated by Atomic Force Microscopy (AFM), Four Point Probe (FPP) and Spectroscopic Ellipsometry (SE), respectively. These properties were exploited for application of the TiO 2 layers as antireflection coatings on monocrystalline silicon solar cells. Our experimental results show that the deposited TiO 2 thin films were polycrystalline, homogenous, compact and relatively smooth. The measured average optical transmittance of the TiO 2 films was about 85-90%. From the ellipsometry analysis, the refractive index of our TiO 2 thin films was found to be n=2,25 at the wavelength λ= 550 nm, with a thickness of 56,2 nm. These experimental results obtained by APCVD are in excellent agreement with the computed results of the TiO 2 refractive index and thickness required for a high quality antireflection coating in industrial conditions. The obtained results demonstrate the real opportunity of the APCVD technique to prepare high quality antireflection coatings for crystalline solar cells. This indicates that the APCVD antireflection coatings may have a high potential industrial application.
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