Dear Zaynab,
"POA on cell" is the solar irradiance incident on the surface of the concentrating module. It is calculated as follows:
POA = DNI * soiling * IAM * alignment * wind flutter * optical
The inputs for the error factors are on the Module and Array input pages.
If you set all of the losses to 1, then you should see that POA = DNI.
Best regards,
Paul.