Heliostat Range of Movement for Chosen Target Simulation

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This documentation is part of the Open Sun Harvesting Project.

Before using a target, it’s a good idea to double check to see if your heliostat is physically capable of reflecting the light to it throughout the day. To make this task easier, I have written a program that outputs the machine’s angles for one day of movement.

Running the Program

Click here to start the program. (I recommend that you right click and choose “Open in New Window” so that you can leave this documentation open.) After you click the “Graph It” button, you should see the same thing that is in the picture below.

The graph represents the path your heliostat will follow during one day of travel based on your selected target. You will find its azimuth on the x-axis and the altitude on the y-axis.


Using the Program

To customize the program for your area, input your latitude, longitude, and timezone. If you live south of the equator, make sure you uncheck the “North of the Equator” option. (I have found that it is kind of hard to click this option if you click in the middle. Try clicking on the upper left hand corner if you have this same problem.) The Northern and Southern Hemisphere Differences in the Sun Tracking / Heliostat Program page explains the difference between the two options.

To choose the time of the year, just fill in the year, month, and day. (The year doesn’t really have that much of an affect, so you can just leave it as it is if you want.)

Some useful dates are…

June 21 (Summer solstice in northern hemisphere / Winter in southern hemisphere)

December 21 (Winter solstice northern hemisphere / Summer in southern hemisphere)

September 22 (One of the equinoxes)

To choose a target, just set the altitude and azimuth for the target.

The default direction for where azimuth = 0 is south.

If you live in the southern hemisphere, you might prefer to to use north as the direction where azimuth = 0. To switch from south to north, just uncheck the checkbox next to “Azimuth = 0 When Pointing South.”



As an example of using this program, let’s say I have a heliostat which, for whatever reason, is only capable of turning +65 degrees along the azimuth.

Now, if I use this heliostat with a target which has an altitude and azimuth of 0, It will work. Check out the bottom right hand corner of the graph and you will see that the maximum range of the heliostat for this target is just within +60 degrees.


Let’s try it again with a target which has an azimuth of 35 degrees and an altitude of 0 degrees. If you look at the graph below, you will see that the range the heliostat will need to move along the azimuth is outside of +65 degrees.

This isn’t a target I would want to use because this heliostat isn’t capable of turning far enough to achieve the correct azimuth.


Fair Warning

Keep in mind that this program is just a simulation. It should be accurate, but I do make mistakes.

This documentation is part of the Open Sun Harvesting Project.

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