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Fixed-tilt - stringing

Jonas Žemaitaitis

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Stringing

There are four main stringing types:

  • Single-row stringing - This stringing type connects every panel in the row in series into a singular string spanning the whole row;

  • U-stringing - This stringing type connects all the panels in the frame in a series connection, with the positive and negative end terminals placed on one side. Please note this stringing requires the number of rows to be an even number;

  • Leap frog - This stringing type connects every second module going to one side and comes back via the remaining modules, with the positive and negative end terminals placed on one side.

  • Custom stringing - This option enables you to manually create custom patterns of one or more strings within one or more PV frames.

For our example, we will select custom stringing. Here we have the option to name our custom preset. We will give it the name 2C20. Then we click Select frame and we can choose one or more frames on which we want to model the custom stringing. In our case, we will work with a singular frame.

Once we have our frame selected, we press the Space or Enter key on the keyboard and we are given the unstringed frame as a canvas to work on. We select the module we want to start on and by left-clicking on it, the module becomes our positive terminal, represented by the + symbol.

Then we go to the right and when we click here, we can see that it gives us some dashed lines. If we were to go back to the module that is right next to our positive terminal and left-click on it, we can see that this module became the negative terminal and the previously-seen dashed lines became intertwined.

This is how we can create a leap frog string in PVcase.

We will repeat the steps for the unused modules: We click on the module just below our other positive module, click on the module on the far-opposite side and return to the start and click on the module just to the side of the positive terminal. We now have a frame stringing preset with two leapfrog strings.

To delete the string, right-click on the entire string - this will remove the string that you drew.

We can mirror this preset should you need to quickly re-orient the preset to have the terminals on the other side of the frame.

To string our frames, we have two options:

  • String area - using this function, we can select a PV area that we want to fully string with this preset on supported frames;

  • String frames - using this function, we can select individual frames to which we would apply these features.

Should we want to remove some or all of the stringing, we can click on Destring Frames, and upon selecting the frames we want to destring, press Space or Enter on the keyboard.

It's important to take into account where we wish to have DC combiners/string inverters ultimately placed, to adjust the direction of strings accordingly. This is more of a recommendation since it is always possible to change strings direction later. For instance, in the example below, we aim to place the electrical devices alongside the yellow line:

Knowing that, we can plan to have the strings on either side of the line facing the line (West frames facing east & East frames facing West). This can help reduce the DC cable run length:

To accommodate that, you may use the mirror function. The mirror function will automatically invert the position of the strings, as can be seen below:

Tips and tricks

After completing the electrical design and adding all labels and devices, you may have noticed a string or two with the polarity around the wrong way. This can be adjusted by selecting a string right-clicking on it, navigating to PVcase, and choosing Reverse string polarity.

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