Testing diffuse luminous efficacy models for Florianópolis, Brazil

This work comprises two parts. The first part presents an evaluation of diverse luminous efficacy models of the solar diffuse radiation available in the international scientific literature. These models were used for the estimation of the luminous diffuse illuminance in Florianópolis, Brazil. This evaluation has taken into consideration not only the precision of the models but also the justification of the physical behavior of the luminous efficacy. The second part of this study presents the evaluation of the three specific diffuse luminous efficacy models developed for clear sky conditions, also available in the international literature. It also presents a new model that is reported for the first time in the present work. These models have not shown clear statistical balance differences among each other when estimating the diffuse illuminance, and except for one, all the studied models can perfectly explain the behavior of the diffuse luminous efficacy against the solar altitude. Furthermore, the evaluation has shown that the models specifically developed for clear skies show no better results than the general all sky models, analyzed in the first part of this work, when estimating the clear sky diffuse illuminance with them. These latter specific models do not show better results in the estimation of the diffuse illuminance for the clear sky conditions, than the ones obtained with some of the general models, analyzed in the first part of this work.