On the determination of coherent solar climates over a tropical island with a complex topography

Many tropical islands aim at developing a greener self-sufficient energy production systems based on renewable energy, notably solar-generated electricity. This work explores the mean diurnal and annual solar cycles over La Reunion island (southwest Indian Ocean: 21 degrees S, 55.5 degrees E), and their spatial behavior, using the Solar surfAce RAdiation Heliosat - East (SARAH-E) satellite-derived data at high spatial (0.05 degrees x 0.05 degrees) and time (hourly) resolutions over period 1999-2016. Comparisons of the SARAH-E data with ground-based measurements over the period 2011-2015 show differences of similar to 15% for diurnal-seasonal variations. The solar resource over the island displays strong spatial variability, with differences larger than 100 W m(-2) between coastal and moun- tainous zones. The mean solar resource is lower on the island than on the nearby sea by similar to 20%. The strongest interactions between the diurnal and annual cycles are found at the windward mid-slopes and near the active volcano, in line with the well-known cloud processes encountered there. A clustering of solar zones, based on diurnal-seasonal cycles, structures the island into a dipole that opposes the western to the eastern side of the island.