How to Effectively and Efficiently Model Solar PV Farm Earthing

SafeGrid Earthing Software can model large solar PV earthing systems.

To effectively model the solar PV farm earthing, you should include enough detail to avoid overestimating touch voltages. The model should include all the interconnecting earthing conductors, array posts, and supports.

This detailed article explains how to model the earthing system for a large-scale solar PV plant:

https://elek.com.au/articles/earthing-design-and-modelling-guide-for-solar-farms/

A sample DXF CAD file of a solar farm earthing system is attached to this article which you can import into SafeGrid.

Modeling solar PV farm earthing may involve long computation times caused by the model's high number of conductors and the system's sheer size. Therefore to efficiently model the earthing, the following is suggested:

• Model a subsection (partial model) of the solar farm earthing and use the worst-case fault current scenario to check if compliance can be achieved. If so, then the full model should also comply.
• Avoid modeling conductors buried close to the ground surface (Z=0). We use depth-based segmentation, which means the nearer conductors are to the ground surface, the more segmentation (dividing segments into more segments) is performed for accuracy. You can model posts as vertical segments from 0.3 m below the ground.
• Reduce the number of segments by modeling only the below-ground segments. You can achieve this by modeling the supports as buried insulated conductors interconnected between the posts. The insulated conductors should be kept at or deeper than 0.3 m, which aligns with the previous suggestion.

• Minimize the number of voltage profile points by increasing the maximum spacing between points. Also, you can create a voltage profile which covers only a corner of the solar farm earthing and the calculated voltages should be respresentative for the rest of the installation.
• Draw your conductors in AutoCAD in drawing layers. For example, all the posts should be in a separate (and named) layer, and all your supports (or insulated buried equivalents) should be in another layer. By doing this, when you import as DXF, you can assign the same conductor types and properties to the conductors (for example, make them all insulated).
• The number of soil layers directly affects the computation time. Multiple shallow soil layers can also affect computation time because conductors that cross soil layers need to be divided into additional conductors. If your soil model consists of multiple horizontal layers, consider reducing (by consolidating) the number of soil layers.