Assessment and mapping of the solar irradiation in Timor-Leste using ERA5, MERRA2 and SOLCAST data

Abstract

This work is part of the Master's thesis in Solar Energy Engineering and aims to assess and map the solar resource in East Timor. To this end, reanalysis data from ERA5 and MERRA2 were used, involving a grid with an area between 123.75º and 127.5º of longitude, and between -9.5º and -8.0º of latitude over a period of 23 years (2000-2022), as well as Solcast data acquired at 39 points distributed throughout the municipalities of Timor-Leste over 16 years (2007-2022). The reanalysis data was subjected to an adjustment of the original grid to a resolution of 0.5º x 0.5º and then to 0.01º x 0.01º by means of triangular bicubic and linear interpolation in order to carry out the evaluation and mapping. In addition, the influence of altitude, cloud cover and precipitation on the solar irradiance was also investigated. The results of the study show that the relationship between the ERA5 and MERRA2 data for the GHI (Global Horizontal Irradiance) variable has a coefficient of determination of R2=0.386, while for the GHI in clear sky conditions it is R2=0.992. The relationships of the Solcast data, also for the GHI, have coefficients of determination R2=0.717 and 0.299, with the ERA5 and MERRA2, respectively. For clear skies, R2=0.930 and 0.944 for ERA5 and MERRA2, respectively. The monthly maps between ERA5 and MERRA2 show a similarity between the months of July and August, with the remaining months being very different.