discrepancy in the results obtained

Good morning,

I would like to ask some information about the formula SAM uses to calculate the 'Array POA rear side direct and diffuse radiation after (IAM)'. In fact how I show in the picture below in some cases the first value of certain days seems to be out of scale in comparison with the data of the hours after.

In the same hour the sum of the 'Array POA rear side direct and diffuse radiation after (IAM)', the Array POA rear side radiation reflected from the ground after (IAM)' and of the 'Array POA rear side radiation reflected from the rear row after (IAM)' does not match with the value reported in Array POA rear side total radiation after reflection (IAM)'; unlike all the other moments of the day.