A simple evaluation procedure is developed for the case study
and the calculation is based on the savings compared to the use
of an electric water heater. Details of the evaluation procedure
are described as follows.
Firstly, the annual heating load is estimated by the following
equation:
Q¼365mcDt ð1Þ
whereQis the required heating load per year;mis the mass of hot
water required per day;cis the specific heat of water; andDtis the
water temperature difference between the inlet and the outlet
temperatures.
Secondly, the useful solar thermal energy collected by the solar
collectors is calculated by
Qu¼AcItgcoll
ð2Þ
whereQuis the useful solar thermal energy per year;Acis the area
of solar collector;I
tis the maximum annual solar radiation received
by the solar collector; andgcollis the efficiency of the solar collector
loop.
The conventional energy consumption is then evaluated: