# r.sun delievering unrealistic Values

I need your help. I'm trying to calculate the global irridiation for a specific area. I'm interested in the results for rooftops in special. I have a DEM, calculated slope, aspect and horizons and started `r.sun` for every day with a monthly changing Linke Factor. All calculated maps (slope, aspect, horizons) seem to have believable values. My Problem is: On the yearly sum (addition of all 365 days) I get values for total global irridiation of about 1900 KW/m². Which is 1,9times more then expected. Especially when the solar constant is only 1368 kW/m².... Could you imagine what went wrong? I'm lost.

• Why are you summing all of 365 days? it doesn't have sense... the global year irradiation, it's the average of all the 654 days not the sum. Sep 2 '14 at 13:37
• sorry, i wanted to calculate the sum of KWh/m² so, as glob_rad gives the Wh/m² per day i sum them up (and divide them by 1000)
– Ulf
Sep 2 '14 at 14:38
• is it neccesary to give input for coef_bh and coef_bf?
– Ulf
Sep 2 '14 at 14:40
• No it's not neccessary. Can you paste here the code of one day and the code that you use for calculating the sum? Sep 2 '14 at 14:59
• I noticed you wanted to delete this question because you've found an answer. Instead of deleting, please consider adding the answer you've found as an answer here, and mark it as accepted, so that people with a similar issue in the future might find your answer. Sep 2 '14 at 18:21