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Solar Water Heating

Solar Water Heating

Solar water heating panels energy yield calculator

m2 degrees
 
  Vhc Th Ti D Qhw R Tf Sf
  Daily hot water demand Required hot water temperature Incoming water temperature Days requiring hot water Daily heat requirement Daily mean solar irradiation Tilt factor to be used Solar fraction
  m3 degrees Celsius degrees Celsius   MJ MJ/m2    
JAN         %
FEB         %
MAR         %
APR         %
MAY         %
JUN         %
JUL         %
AUG         %
SEP         %
OCT         %
NOV         %
DEC         %
Annual water heating requirement (P)   MJ
Annual heat amount converted from solar energy (Q)   MJ
or   kWh equivalent (1kWh = 3.6MJ)
Annual solar fraction (Q / P)   %

 

  1. This is a simple calculator for appreciating the year-round performance of solar water heating systems. It is not intended to be a design tool because many simplifying assumptions have been made. Solar panels are assumed to have a constant efficiency, and facing south while tilted at the angle chosen. The solar water heating system is assumed to serve the purpose of pre-heating the incoming water. When solar radiation is insufficient, the gas/electric water heater will make up the difference.

  2. For average system efficiency, can try 30% to 40% for flat-plate collectors, and 40% to 45% for evacuated tube collectors. Note that efficiency also depends on the tilt angle and orientation of the collectors.

  3. Daily mean solar irradiation figures are based on data of King's Park weather station.

  4. The formulae adopted are:
    Qhw = Vhc x 4.2 x (Th - Ti)
    Sf = A x R x Tf x Eff / Qhw, equated to 100% if this exceeds 100%
    Annual water heating requirement = summation over twelve months of (D x Qhw)
    Annual heat amount converted from solar energy = summation over twelve months of (D x Qhw x Sf)