Public Energy Alternative Software
Solar Energy Calculator for water heating
Slope (inclination) [degr]
Azimuth (orientation) [degr]
All data should be entered with a dot separator rather than a comma.
Slope (inclination) is the angle between the plane of the solar collector and the horizontal axis. If a panel is lying flat, then the slope angle is 0 degr.
Azimuth angle means the deflection of the collector axis from south direction, so the angle of the collector, which is pointed exactly south is 0 degr.
(east -90 degr.).
You can always edit the data and confirm it pressing button calculate.
Solar thermal system :
Local radiation data
Enter the monthly average radiation (Hm) for each month of the year.
Take into consideration the location of installation, panel slope, azimuth.
Jan Feb Mar Apr May Jun [kWh/m²/month]
Jul Aug Sep Oct Nov Dec [kWh/m²/month]
You can use data from http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php . Use PV Estimation option, mark a location on the map and fill Fixed mounting option (slope and azimuth) then press calculate key. You can select the fields optimize slope and next optimize azimuth to find out what the slope and azimuth are optimal for you location.
Local daytime temperature
Enter the monthly average daytime temperature (TD) for each month of the year.
Jan Feb Mar Apr May Jun [ºC]
Jul Aug Sep Oct Nov Dec [ºC]
You can use data from http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php . Use Monthly radiation option, select a location on the map and mark
Average daytime temperature.
Local daytime hours
Enter the monthly average number of daytime hours for each month.
Jan Feb Mar Apr May Jun [hours]
Jul Aug Sep Oct Nov Dec [hours]
You can use data from http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php . Use Daily radiation option, select a location on the map and subsequently every month, count the number of hours of global irradiance on a fixed plane.
Fuel consumption for water heating
What kind of fuel do you use for water heating at present ? How much is fuel consumed for it in a month ?
Coal [kg/month] or Oil [l/month] or Electricity [kWh/month] or Natural gas [m³/month]
Hot water usage
How much hot water do you use per month and how much does it cost you ?
Hot water [m³/month] Monthly costs [local currency]
Enter the temperature of hot and cold water in your tap
Cold water temperature [ºC] Hot water temperature [ºC]
I plan to install this solar thermal system
Surface of collectors absorber [m²] Number of collectors Optical efficiency [%]
Value k1 [W/m²/K] Value k2 [W/m²/K²] Heat exchanger and DHW circulation losses [%]
You system supplier should give you detailed information about linear heat correction value k1 , nonlinear heat correction value k2
and other important parameters.
You can use the standart parameters: Flat-plate collector ; optical_efficiency=80%, k1=4 W/(m²K), k2=0,01 W/(m²K²) Vacuum tube collectors ; optical_efficiency=80%, k1=1,5 W/(m²K), k2=0,005 W/(m²K²)
Total cost of instalation [local currency] (1)