Currently i am trying to calculate sunshine hours duration from r.sun (GRASS Plug in ) from QGIS 2.12. I want to calculate sunshine duration for 21 st jun and 21st December for same elevation data set. After time consuming process i managed to get sunshine duration. But when i saw output for summer as well as winter both duration hours value are same. Is it related to DEM size or tools issue. because similar process i run with ArcGIS solar radiation tools and got very accurate results. if anybody worked on this please let me know
Have you seen this blog post using r.sun.hourly from GRASS: http://courses.neteler.org/will-the-sun-shine-on-us/
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