How do I set up a model file that contains solar panel groups?

This article makes use of an MDL file to define the vehicle's visual structure, solar panels, and articulation properties. It assumes that you are familiar with the internal structure of an MDL file. If you are not, then please consult the STK Help for more information.

You can also use COLLADA models to convert CAD models into a format readable by STK. See our Help and FAQ: How to Convert CAD Models for Use in STK for more on using COLLADA models. For STK versions 11.5 and later, STK natively supports the .glTF format, a high-fidelity visual format that leverages the free and open-source Blender suite. AGI recommends the .glTF format for use with STK, and you can find additional documentation on our Help and FAQ: Converting Models to glTF for STK pages.

Even if you didn't build the model and have no idea where within the text file the cells are defined, we'll show you how to find the definition for the cells after you open the model in Modeler, AGI's stand-alone model file viewing utility.

Once you load the model and it is visible — you may have to zoom in — you can discover where the definition of any component is by holding down the Ctrl key and right-clicking anywhere on the model. The component selected will flash red. The component name and what line number it can be found on within the text file will appear in the information section just below the OpenGL window.

Other mouse-key combinations are:
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A. DEFINING THE POLYGONS TO USE  
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B. ARTICULATIONS AND POINTING: Setting up the "Pointing" command

We need to make sure that the array in the panel above is parented to articulates, so that it can rotate around the yoke and point at the Sun.

Below, on line 761, we see the parent component that refers to all the child components that make up the solar arrays. The articulation is around the Y axis, and the pointing command is set on the X axis.

Give the "pointing" command a name and a vector on which to point along. Pointing depends on which axis is perpendicular to the face of the panel.
 
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C. SOLAR PANEL GROUPS AND THEIR EFFICIENCY: Defining the solar panel groups and the efficiency rating for the panels

You can place the group definition and efficiency rating anywhere in the text file, as long as it remains outside the definition of the model. Here it is done at the top of the file. Using our example file again, notice the text in italics below:
 
Each solar panel group must have its own definition. You can either have two groups, one for each array, or you can have both arrays within the same group, as we have done here.

Each would begin with the argument "SolarPanelGroup" followed by the solar panel name as defined at the component level.

The efficiency rating depends on the design and construction of the panels used. This number is a percentage of how well the solar cell can convert solar to electrical energy. The higher the number is, the more efficient the panels are. In this example, the efficiency is 14.0%.

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CONCLUSION:
Once you set these three conditions, when you load  the model into STK, the arrays will automatically begin to track the sun.