The radiation reaching the earth’s surface can be represented in a number of
different ways and one of the ways is through GHI determination. This study
determined the Global Horizontal Irradiance (GHI) in the Province of Bukidnon. GHI
is the maximum concurrency of solar radiation at specific time and location on the
surface of the earth. It was determined monthly from January to December 2014
using the R.sun model that runs in an open source Grass Geographical Information
System (GIS) software which can compute direct (beam), diffuse and reflected solar
irradiation raster maps for a given day, latitude, surface and atmospheric conditions.
Inputs such as topography, location, Linke Turbidity and ground albedo, slope and
aspect and sun’s declination were also taken into account in the calculation. The
results suggest that the values of GHI in a clear sky condition differ by almost 90%
greater than the real sky condition. The highest GHI values were recorded in the
month of January and May for clear and real sky, respectively. Thus, the output of
this study recognized and may utilize further to assess the solar energy potential
of the Province in terms of GHIs.