Experimental assessment of the solar energy potential in the gulf of Tunis, Tunisia

This work carries out the availability of the global solar radiation over the site of Borj-Cedria in the gulf of Tunis (36°43′04″N latitude and 10°25′41″E longitude), Tunisia. Global solar radiation variability was assessed on hourly, daily, monthly and seasonal scales. Solar potential in the gulf of Tunis was evaluated using the solar radiation data collected by the meteorological NRG weather station installed in the Center of Research and Technologies of Energy (CRTEn) in the Borj-Cedria area. The collected measurements during the last three years (2008, 2009 and 2010) were based on 10 min time step. These data have allowed us to evaluate the global solar flux, the sun duration, the yearly and the seasonal frequency distribution of the global solar radiation. Moreover, a conventional model has been used to estimate the hourly solar radiation on a horizontal plane and it has been validated by experimental measurements in specific days. The results show that the global solar radiation predicted by the conventional model has a good agreement with the experimental data during the clear sky conditions with a mean absolute percentage error (MAPE) of 4.1%. However, the limitation of the conventional model appears under the cloudy sky weather which is proved by the highest value of relative error percentage reaching 14.26% occurred during the autumnal equinox day.