P50/P90 simulation error

when I do the simulation it gives me the following error:
"Calculated negative diffuse horizontal irradiance" I would like to know if this is really an error or it only appears because I am using GHI and DNI as data I attach a couple of files of the historical data that I am using: 

Hi Sergio,

That error message tends to be for time steps at the beginning and end of the day when the sun is low on the horizon and the array is not producing very much power. If that is the case for you, then you can ignore the messages because the problem does not have a large impact on the total monthly or annual energy value.

Best regards,
Paul.