Solar Radiation Simulation Model

Introduction

This Solar Radiation Simulator is a program in JavaScript for generating numerical data with the same properties as real solar radiation data in the tropics.

To use the program enter the input values for the data you want in the form below, and click the button at the bottom of the form. The data file then appears in a separate window.

Information Input

The items of input required are as follows:

Latitude (deg):
The latitude given must be within the interval +25 deg (north of the equator) to −25 deg (south of the equator) because the model is correct only for the tropics. Initially the latitude "15" (for Central Thailand) appears in this text box, but you should fill in the correct latitude of your location.
Mean daily solar irradiation on a horizontal surface each month (MJ/m2):
Initially typical values for Central Thailand appear in the monthly text boxes, but you should fill in the correct values for your location.
Orientation of tilted surface:.
The Azimuth (deg W) is the angle between south (= zero degrees) and the direction in which the tilted surface is facing, measured towards the west. For example, west is 90 degrees, north is 180 degrees, and east is −90 degrees. The Tilt angle (deg) is the angle between the surface and the horizontal plane, which is the same as the angle between the normal to the surface and the zenith.

Days of the Year

You can do the calculation for the whole year (365 days), or for selected days at regular intervals. Day #1 is 1 January, day #2 is 2 January, ..., day #365 is 31 December.

The numbers which appear initially in the form compute data from day #17 to day #365 with daily step 30; in other words, one day in the middle of each month: 17 Jan, 16 Feb, 18 Mar, 17 Apr, 17 May, 16 Jun, 16 Jul, 15 Aug, 14 Sep, 14 Oct, 13 Nov, 13 Dec.

Enter the first and last day, and the number of days in each interval step, to get data for the days you want.

Solar Radiation Simulator

Copyright © 1999 by R. H. B. Exell

Latitude of place for which simulation is to be done:

Latitude (deg):   Latitude must be in the range −25 to 25.

The latitude of central Thailand is shown. Change this to the latitude of your location.

Mean daily solar irradiation on a horizontal surface each month (MJ/m2):

Jan:   Feb:   Mar:   Apr:   May:   Jun:
Jul:   Aug:   Sep:   Oct:   Nov:   Dec:

Typical values for central Thailand are shown. Change them to the values for your location.

Orientation of tilted surface:

Azimuth (deg W from S):   Tilt angle (deg):

The angles for a surface facing south tilted 15 degrees are shown. Change these angles to the angles for your surface.

Days of the year for which simulation is to be done:

Compute data from day # to day # with daily step

The numbers for one day in the middle of each month are shown. Change these numbers to get the days you want.

Select simulated data to be included in file:

Day in the year.

Daily clear sky global irradiation (MJ/m2).   Mean daily global irradiation (MJ/m2).   Random daily global irradiation (MJ/m2).

Hourly position of the sun:
Azimuth of the sun (deg W from S).   Zenith angle of the sun (deg).
Hourly clear sky irradiance (W/m2):
Global.   Beam.   Diffuse.   Total on tilted surface.
Mean hourly irradiance (W/m2):
Global.   Beam.   Diffuse.   Total on tilted surface.
Random hourly irradiance (W/m2):
Global.   Beam.   Diffuse.   Total on tilted surface.

(Hourly values are at 6:00, 7:00, ..., 17:00, 18:00 apparent solar time.)

To make your data file click this button.
Your file will then appear in the "Data File" window with the words "End of Data File" at the end.

By R. H. B. Exell, 1999. King Mongkut's University of Technology Thonburi.