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Most solar module manufacturers guarantee the minimum performance of their modules for 20 to 25 years. But some time after their installation, one observes faults which appear on the various components of these modules. During long-term exposure to severe climatic conditions, these faults, which accumulate over time, lead to performance losses of the module. This performance degradation is due to several factors such as humidity, temperature, heat, irradiation etc. These factors cause various degradation processes which can be electrical, chemical, mechanical, thermal, etc. The tropical zone, the middle of our study being characterized by high heat and humidity, has definite impacts on the electrical parameters of photovoltaic modules. The electrical parameters degradation is among others cause of photovoltaic modules performance loss. This study purpose is to study the degradation of the shunt resistance, the series resistance and the form factor of photovoltaic modules installed in tropical areas in order to appreciate their impact on the performance loss of the latter. For that, we used Peck performance degradation analytical model and Braisaz degradation analytical models of shunt resistance and the series resistance to calculate over a period of forty years, in real conditions in the tropical environment, the degradation of these electrical parameters of the photovoltaic module. The results obtained are compared to those obtained during the Hulkoff experimental tests in the state of Miami in Florida in 2009. The degradation rates obtained in the six cities concerned by the study vary between 17.33-35.67% for resistance shunt, between 3.77-7.55% for the series resistance and between 8-19% for the fill factor. In addition, these electrical parameters degradation rates obtained experimentally by Hulkoff and taken up by [1], are respectively 35.14% for the shunt resistor, 9.43% for the series resistor and 3.03% for the fill factor over the study period. So, future researches on crystalline silicon photovoltaic solar module can be effect of Damp-Heat on short circuit current and open circuit voltage in tropical area.

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We analyze analytically the effects of anisotropy in permeability and that of a transverse magnetic field on thermal convection in a porous medium saturated with a binary fluid and confined in a horizontal cavity. The porous medium, of great extension, is subjected to various conditions at the thermal and solutal boundaries. The axes of the permeability tensor are oriented obliquely with respect to the gravitational field. Based on a scale analysis, the velocity, temperature, and heat and mass transfer rate fields were determined. These results were validated by the study of borderline cases which are: pure porous media and pure fluid media discussed in the literature. It emerges from this study that the anisotropy parameters influence the convective flow. The application of a transverse magnetic field significantly reduces the speed of the flow and thereby affects the temperature field and the rate of heat and mass transfer.

Multi-junction photovoltaic cells composed of III-V semiconductor materials are widely used in photovoltaic systems. They offer very high efficiencies compared to single-junction photovoltaic cells. Knowledge of the behavior of their electrical parameters in real operating conditions is essential for their best use. This work presents an analytical model for predicting the behavior of the output electrical parameters of the sub-cells composing the Ga0.67In0.33P/GaAs/Ga0.70In0.30As triple junction photovoltaic cell, operating under the actual conditions of two selected sites. The dependence of the external quantum efficiency at the wavelengths corresponding to the absorption ranges of the top (Ga0.67In0.33P), middle (GaAs) and bottom (Ga0.70In0.30As)$$ sub-cells is analyzed and discussed. The influence of temperature and irradiation on the V oc ,J sc, F F and η parameters is discussed taking into account the meteorological characteristics of two selected locations. An average daily conversion efficiency of the Triple-Junction solar cell of 37.24% and a daily electrical power of 1613.1 W/m2 for the typical day(TD) of the sunniest month of the Bujumbura site were found. Similarly, under the same conditions, for the Bugarama site, we found an average daily efficiency of 37.28% and a daily electrical power of 1619.7 W/m2. The developed model can also be used to design a more suitable Photovoltaic system at any specified place, provided that local weather data is available.