Horizon Shading hourly - monthly difference?

[Rapha123]

Hi,

When I run a simulation which has horizon shading effects and also output the hourly file, there is a difference in the monthly HrzLoss values when you export a customised table compared to the sum of the hourly values which have been exported on an output file. I've tried this on a few projects and got the same results, with the monthly values greater than the sum of the hourly values. The hourly values are given in W/m2 but summing them should be equivalent to the monthly value given in kWh/m2. Is this a bug or am I doing my calculations wrong?

Thanks,

Rapha

[André Mermoud]

I don't know. Normally the values of a given variable should match between the monthly table and the hourly values on the ASCII file, as this is the same variable in the program.

However you are right. I just tried and also observed a slight discrepancy (0.8%, i.e. 0.3 kWh/m2/year on the horizon loss in the monthly tables). This is probably due to accounting the monthly values when the Incident irradiance is below the threshold of 10 W/m2, what is not done in the hourly values. I will check.