Questions about SWH technical manual

Hi Paul, I have some questions about the technical manual given in sam´s solar water heating model page.
About the equation 2.1.11, where does this assumption came from? and in the case that it is using internal energy, what does it happen about the specific heat? because fron my point of view, the value that should be used is that from constant volume (Cv).
I'm working on a thesis about this issue and also about wind and photovoltaic energy, occupying sam as a validation model, so I´m trying to understand how does this program works.

Best regards and stay healthy.

Hi Aldo,

I'm not sure about that assumption for Equation 2.1.11 in the draft DiOrio (2014) Technical Manual for the SAM Solar Water Heating model available from sam.nrel.gov/solar-water-heating .

Best regards,
Paul.