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 Heliostat Target Efficiency Simulator

To make it easier for people to check whether or not their chosen target is the best one, I uploaded a program to this site which first simulates the angles between the sun and the target and then calculates the percentage of light that hits the heliostat based on those angles.

Make sure that you check out the page "How to Maximize Your Heliostat's Efficiency by Choosing Good Targets" before using the program so that you have a good idea of what it is showing you.

_{Starting the Program}

Click here to start the program. It will open in a new window and run in your browser. After you click the "Graph It" button, you should see the same thing that is in the picture below.

 

_{Using the Program}

To customize the program for your area, input your latitude, longitude, and time zone.

 

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."

 

_{Making the Program Explode}

There are certain circumstances where the math that calculates the angles for the heliostat breaks apart. I've only ever seen it happen when using targets with either fairly large or fairly small values for the azimuth. I've never bothered to put in the time to fix it because targets with extreme azimuths aren't very efficient to use.

Targets that are mostly in front of the heliostat are best.

The best way to learn which is a good target and which is bad is by experimenting.

If you manage to create a graph which "breaks" like you see in the picture below, then this would be a target that you probably shouldn't use (at least during the time of the day when the break occurs.

The best time of the year to check for this behavior is the summer solstice.

If your graph looks smooth and continuous like the one in the picture below, then you should be good to go.

Fair Warning

Keep in mind that this program is just a simulation, so you shouldn't view the results as absolute truth. As with all computer programs, they are often plagued by human error, both the programmer's and the user's (mostly the user's :^)(ok usually not the user's). It does its job, but there are a lot of variables involved which could mess things up, so make sure the results make logical sense before assuming them to be correct.

 

Have fun!

 

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