To fully grasp the trunk bus system in PVFARM, it's essential to understand how circuits work within the platform. This guide will walk you through the basics of circuit hierarchy, parent-child relationships, and how to manage your layout effectively.
Circuit Overview
In PVFARM, circuits are represented by different shades of the block color, with each shade corresponding to a specific combiner box. The system will automatically break up the trackers into circuits, more on that later in the article.
Exploring Parent and Child Relationships
In PVFARM, components are organized in a parent-child hierarchy:
eg. In this image the DC combiner box is the parent and the trackers connected to it are the children.
Using the Model Explorer you can navigate this hierarchy:
Select a combiner box and go to "Children" to see connected trackers.
Go "Up" in the hierarchy to move from the combiner box to the inverter, then to the transformer, and finally to the substation.
Using the "Page up" and "Page Down" buttons allow you to quickly change your selection where "Page Up" goes up one level in the hierarchy and "Page Down" does down one level.
Two-High Configurations
In this setup, combiner boxes should group trackers logically to avoid circuit overloads and circuits crossing over where the trunk bus line will be.
When generated, LV wires will run from the inverter and run DC Feeders to the north and/ or the south. You can use this as a potential option where you make sure the equipment and road are centrally located.
Reassigning Trackers
To move a tracker to a different circuit group (or move any children between parents):
Select the tracker.
Choose the parent combiner box while holding Control + P.
Press "Page Down" to confirm the reassignment.
Ensure you don't overload any combiner box or load breaker switch. PVFARM calculates the maximum number of trackers per combiner box based on:
Combiner box amp rating (e.g. 400 amps).
NEC multiplier or Safety Coefficient (e.g. 1.35).
String current (e.g. 13 amps per string).
String number (e.g. 4 strings)
So in the example, we have 400 / 1.35 / 13 / 4 = ~5.69. So the Combiner Box can support up to five trackers.
Visualizing and Managing Circuits
To avoid overloading circuits:
2D Map- Visualize your setup using the Low Voltage Panel.
Run the LV Wires and select “Low Voltage Wiring 2D Map” to see wire connections.
Single Line Diagram- Select the transformer for your block. Open the transformer’s "Single Line Diagram" from the object details. See a SLD view of your circuit layout.
Example Scenario
If you move a tracker and accidentally overload a combiner box (e.g., adding a sixth tracker to a five-tracker limit), you'll need to redistribute trackers to balance the load. Adjust accordingly to ensure no combiner box exceeds its capacity.
Conclusion
This guide has covered the basics of circuit management in PVFARM. In the next article, we’ll dive deeper into analyzing and fine-tuning your setup for optimal performance.