Analysis of the temporal variability of solar radiation in Douala – Cameroon.

One of the solutions for energy deficit in Central Africa is to promote renewable energy sources. Several studies have shown that Cameroon has a high solar potential. The knowledge of the solar variability represents a determining factor for design, dimensioning, performance assessment, and energetic management of renewable energy conversion systems. In this work, we analyze the behavior of different solar cycles mainly for the region of Douala. Observed data (temperature, insolation and precipitation) and satellite products (Solar irradiation Data provided by Soda Solar Project and cloud product acquired from Meteosat Second Generation (MSG)) were computed. The result shows the existence of forth solar season: The great dry season corresponding to the most enlightened period is in December – January - February (DJF), the great rainy season with the least illuminated period detected in June – July – August - September (JJAS). The two intermediate periods, March – April – May (MAM) and October – November (ON) correspond to semi-illuminated period (illuminated in the morning and dark in the afternoon and vice versa). Using a Hierarchical Clustering Analysis (HCA), we found that Douala has 5 types of solar diurnal cycle. A characterization of sky condition during the 5 solar cycles was carried out. The analysis of the situation of sky confirmed clearly that clear sky condition is observed during the illuminated cycle and a cloudy sky condition is detected for the dark cycles.