Hi Afin,
From the Solar Water Heating model description in Help:
"The solar water heating (SWH) model represents flat-plate solar collectors with a one tank water or glycol storage system and a auxiliary electric heater. "
You can find more information about the model in Help, and a detailed description in DiOrio, N "Technical Manual for the SAM Solar Water Heating Model" (Draft) available at
sam.nrel.gov/solar-water-heating.html
.
Best regards,
Paul.