Ls = solar energy supplied to the load (GJ).
Lu = useful load (GJ).
Therefore, after Qst is estimated, fTL can be obtained from the f-charts as usual. The solar fraction f can also be represented by Ls/Lu, i.e., the solar energy supplied to the load divided by the useful load, then Eq. (11.74) becomes:
Storage tank losses can be estimated by considering that the tank remains at Tmin during the month or by assuming that the average tank temperature is equal to the monthly average collector inlet temperature, which can be estimated ...