Thanks for the hint.I did the calculations with the default value of the linke Linke turbidity coeffcient, which is 3.0 In the output table of PVGIS the Linke turbidity coeffcient is in february 2.7, so I think this should be okay.
Any other ideas?
Alberto Pettazzi schrieb:
Maybe the problem is due to a Linke turbidity coeffcient too low (atmosphere too transparent)...Frank Reekers escribió:the global radiation, calculated with r.sun, seems to be very high in comparison to PVGIS (Photovoltaic Geographical Information System).- r.sun for 14. Feb: ~2363 Wh/m² per day- PVGIS: 1330 Wh/m² per day Irradiation on horizontal plane for february on averageBelow the detailed steps I did in GRASS and with PVGIS: 1. PVGIS:a) http://re.jrc.ec.europa.eu/pvgis/apps3/pvest.php -> search for location 'Osnabrueck, Germany' -> choose monthly radiation -> click calculate -> the output table shows 1330 Wh/m² Irradiation on horizontal plane for february.2. GRASSa) Take an existing DEM with the resolution of 1m and set all z-values to 68m to have a completely horizontal plane:GRASS 6.4.0RC6 (GRASS)> r.mapcalc dsxx94c68=dsxx...@permanent*0+68.00 b) Set Region GRASS 6.4.0RC6 (GRASS)> g.region rast=dsxx94c68 c) Create slope & aspect:GRASS 6.4.0RC6 (GRASS)> r.slope.aspect elevation=dsxx94...@permanent slope=sdsxx94c68 aspect=adsxx94c68 --overwrited) Run r.sun for day 45:GRASS 6.4.0RC6 (GRASS)> r.sun elevin=dsxx94...@permanent aspin=adsxx94...@permanent slopein=sdsxx94...@permanent glob_rad=g45phxx94c68 day=45 --overwritee) Get global radiation:GRASS 6.4.0RC6 (GRASS)> r.what input=g45phxx94c68 east_north=3435430.596,5794315.993435430.596|5794315.99||2362.9213867188 Is there a reasonable explanation for this or did I something wrong? Thanks for your help Frank _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
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