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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.

In this work, the excitons distribution function in organic bulk hetero junction solar cells, at a depth z has been determined from solving the charge continuity equation, by exploiting the Laplace transform with appropriate boundary conditions. Next, the influence of the electron-hole pair separation distance on the excitons dissociation probability, the internal quantum efficiency and the binding energy, has been studied. The simulated results show that the probability density of the carriers photo generated depends on the generation rate, excitons dissociation and the charge carriers in the cells. The potential improvement of the internal quantum efficiency of charge generation depends on electron-hole pair separation distance, the excitons dissociation probability into free charges and depends strongly on the optical absorption of the photons in the active layer.

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.