Using Tracking in a Solar Design

This article is in the Projects > Design section of the app.

If a project requires tracking, you can customize the tracking system on OpenSolar. (For information on a fixed tracking system, please refer to this article).

Once you have designed your solar panel array in the Design page, you will be able to switch on tracking.

First, ensure the panel array is selected by clicking on it (a yellow box should appear around the array).

Then navigate to the left toolbar, select Advanced Layout and choose the tracking mode from the dropdown called "Tracking Mode".

You have a few different options here. Here are brief descriptions of them:

• None (fixed) - This is the default setting which will not apply any special output changes.
• 1 Axis Horizontal (No Backtracking) - This is the tracking mode in which the panels tilt left and right about an axis which runs from the top to the bottom of the panel to track the sun's daily movement. So if a panel group is facing north or south then the tracking will happen in the east and west directions.
• 1 Axis Horizontal (With Backtracking) - This is the same as above except that the SAM algorithm for backtracking (where the panels change their tilt to minimize self shading) is implemented.
• 1 Axis Tilted (No Backtracking) - This is the tracking mode in which the panels tilt forwards and backwards about an axis which runs from one side of the panel to the other in order to follow the sun's seasonal movement.
• 1 Axis Tilted (With Backtracking) - This is the same as above except that the SAM algorithm for backtracking (where the panels change their tilt to minimize self shading) is implemented.
• 2 Axis - This is where the panels can rotate both east to west and north to south to track the daily and seasonal movement of the sun.

The impact of Backtracking

SAM’s backtracking for one-axis tracking algorithm was developed by NREL for SAM. It involves checking whether the panels in certain rows will be shaded by other panels or not and adjusts accordingly.  

Backtracking should be used ONLY when there is self-shading between rows of modules. If there is no self-shading then backtracking attempts to minimize this non-existent shading loss so the tilt is sub-optimal while the backtracking does this, hence why there is less energy output if backtracking is enabled WITHOUT enabling self-shading.

If you wish to read more about this, please see here.