Estimation of Diffuse Solar Radiation in the City of Natal – RN Based on the KT Index

Objective: This study aimed to validate and compare three models for estimating diffuse solar radiation in the city of Natal - RN, using data from the SONDA Project, with a focus on developing and validating the Ubial model. Theoretical Framework: The research is based on solar radiation concepts, which are essential for optimizing photovoltaic systems. Accurate models for estimating diffuse radiation are necessary for the efficient performance of these systems, especially in locations like Natal - RN. Method: The methodology adopted a quantitative and comparative approach, analyzing the Erbs, Bourges, and Ubial models. Data from the SONDA Project were used, and the statistical analysis included evaluating the Mean Bias Error (MBE) and correlating the data with the clearness index (Kt). Results and Discussion: The Ubial model showed superior performance, with a negative MBE, indicating greater accuracy without overestimating the data. These results were discussed in light of the theoretical framework, highlighting the suitability of the Ubial model for the climatic conditions of Natal - RN. Research Implications: The implications of this research include the potential application of the Ubial model in other regions with similar climatic characteristics, contributing to the optimization of photovoltaic systems. Originality/Value: This study introduces an innovative model that incorporates additional variables, resulting in more accurate estimates of diffuse solar radiation, with a direct impact on the solar energy field.