Downscaling of global solar irradiation in R

TL;DR

This paper presents a methodology using R software to improve the spatial resolution of satellite-derived solar irradiation data through downscaling techniques, including topographical analysis and kriging, demonstrated in La Rioja, Spain.

Contribution

It introduces a novel R-based approach combining topographical analysis and geostatistical methods for downscaling solar irradiation data in complex terrains.

Findings

25.5% reduction in mean absolute error compared to original data

Effective integration of topographical and geostatistical methods

Improved accuracy in solar resource estimation in complex terrains

Abstract

A methodology for downscaling solar irradiation from satellite-derived databases is described using R software. Different packages such as raster, parallel, solaR, gstat, sp and rasterVis are considered in this study for improving solar resource estimation in areas with complex topography, in which downscaling is a very useful tool for reducing inherent deviations in satellite-derived irradiation databases, which lack of high global spatial resolution. A topographical analysis of horizon blocking and sky-view is developed with a digital elevation model to determine what fraction of hourly solar irradiation reaches the Earth's surface. Eventually, kriging with external drift is applied for a better estimation of solar irradiation throughout the region analyzed. This methodology has been implemented as an example within the region of La Rioja in northern Spain, and the mean absolute error found is a striking 25.5% lower than with the original database.