Single-axis trackers - stringing

Stringing types

Select the stringing option in PVcase that best fits your site layout and electrical design requirements:

• 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 panels in the frame in series, with the positive and negative end terminals 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 to one side and returns via the remaining modules, with the positive and negative end terminals on one side.

• Manual Stringing - This is an interactive electrical design feature that allows you to manually define stringing paths by drawing a path directly across solar modules in your drawing workspace.

• Smart Stringing - This automated method groups solar modules into strings based on a user-defined module range and the "Row End Exception," which determines how leftover modules are handled.

  • Leave Unstrung: Excludes extra modules at row ends from the stringing plan.
  • S/U String: Loops leftover modules into an S- or U-shaped pattern to complete a string within the row.
  • Jump Row: Extends leftover modules into the next row to complete the string length.

  Note: Smart Stringing is primarily used for fixed-tilt systems, but is also available for single-axis trackers (SAT).

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

Workflow example

For this example, choose Custom Stringing to create a more personalized leapfrog solution. Name your preset (for example, 1C81), then click Select frames and choose the frame you wish to string. In this case, we'll select just one frame.

Once you have the frame selected, press Space or Enter, and the unstringed frame becomes your canvas. Select the module you want to start with, and left-click it to make it our positive terminal, represented by the + symbol.

Then left-click the module next to your positive terminal to assign the Negative (-) Terminal. The previously seen dashed lines become intertwined. This is how we can create a leapfrog string in PVcase.

Repeat the steps for the unused modules: Click the module directly below your first positive terminal, click the far-opposite module on that row, and return to click the adjacent starting module to complete the second string.

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

You can mirror this preset if you need to quickly reorient it so the terminals are on the other side of the frame.

Stringing

In order 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. 

To remove some or all of the stringing, click Destring Frames, select the frames you want to destring, then press Space or Enter.

String Orientation

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

Based on that, we can have shorter DC cables, if each string is facing its own device. This would mean having the strings facing South, in the upper part of the design:

And have strings facing north, at the lower part of the design. Which can easily be accomplished using the mirror function. The mirror function will automatically invert the position of the strings, as can be seen below:

Reversing strings

After completing the electrical design and adding all labels and devices, you may notice a string or two with the wrong polarity. You can adjust this by selecting a string, right-clicking it, going to PVcase, and choosing Reverse string polarity.