Comparison of three solar radiation models and their validation under all sky conditions – case study: Tetuan city in northern of Morocco

To optimize the use of solar energy, a fundamental need is to get to know the amount of solar radiations at a specified Earth location by using the available climatological measured data. The present work aims to predict direct, diffuse and global solar fluxes depending on the sky-condition at a given position, in our case Tetuan city in northern of Morocco (35.57361 latitude, −5.37528 longitude). To do this, we have retained three empirical models from literature, such as ASHRAE, Campbell and Benjamin et al. models. The results obtained by these models with the acquired data by the local meteorological station show different level of accuracy and it has been concluded that some models can be preferred to estimate the solar radiation intensities for the studied site and for other locations that have similar climate conditions.