CSP Parabolic Trough

Dear Sir,
with my version of SAM 2015.6.30 (CSP Parabolic Trough Physical) I have one situation with some hourly output values of "Field thermal power produced" higher than values of "Field thermal power absorbed". In my understanding : (Field Thermal Power Produced = Field Thermal Power Absorbed – Field Thermal Power Header Pipe Losses - Internal Energy Increase). Is it correct? How is possible an higher value?
Thanks in advance
Best Regards

Dear Carlo,
There are a couple of situations that may cause the solar field thermal power produced to be greater than the thermal power absorbed by the field.
1. At night, SAM shows the absorbed thermal power as negative due to receiver and header pipe losses, but it sets the power generated by the field to zero:

2. At the end of the day, some heat remains in the field HTF and receiver tubes:

Best regards,

Paul.