I have two questions related with SWH system circulation pumps:
1) How does SAM calculate the amount of hourly electricity that circulation pumps spend in Solar water heating system?
I checked the official SAM help file and "Technical Manual for the SAM Solar Water Heating Model", but could not find an answer to this question.
Does SAM just use the actual "Pump Power (W)" input as the hourly overall consumption of circulation pumps?
2) If yes, then in which cases are these two pumps considered to be working?
NREL's "Technical Manual for the SAM Solar Water Heating Model" mentions the pump power as one of the parameters in calculation of saved energy (Qsaved):
Qsaved = Qaux,only - Qaux - Ppump
But when does SAM consider the pumps to be working, and when it does not?
Thank you for the reply.