Sol-Ark PCS 200A Power Control System Application Note

Key Concepts and Capabilities

This application note provides guidance on designing and commissioning Sol-Ark inverters with 200 A pass-through. The primary goal is to maximize Power Control System (PCS) compatibility for whole-home and large-load applications, ensuring code-compliant interconnections (NEC 705.13).

• 200 A Pass-Through: Allows the inverter to be placed in-line with a standard 200 A residential service feeder.
• PCS (Power Control System): Uses grid-sense Current Transformers (CTs) to dynamically limit export and cap back-feed currents, satisfying utility non-export rules.
• Self-Consumption Optimization: Prioritizes serving local loads from PV/battery, importing only deficit power from the grid.

Design Flexibility

The PCS feature allows for flexible interconnection methods:

• Breaker-Fed (Load-Side): Enables interconnection with a larger breaker than traditional 120% busbar rules allow, provided the system is accepted by the AHJ/utility.
• Supply-Side (Line-Side Tap): Useful when the main load center cannot accept additional back-feed. The PCS still controls export at the service point.
• Whole-Home 200 A Pass-Through: The inverter acts as the gatekeeper between the utility and the house, ensuring non-export and keeping service conductors within ratings.

CT Hardware and Installation Details

Proper CT placement is critical for the system to function correctly. Follow these guidelines:

• Conductors: Install CTs only on ungrounded (hot) service conductors; never on neutrals or grounds.
• Orientation: Follow the arrow/labeling. The arrow should point toward the load (the grid for service conductors).
• Location: Place CTs on service conductors upstream of all load panels for global control.
• Lead Routing: Keep CT leads away from high-noise cables, use twisted pairs, and respect maximum lead length.
• Verification: Confirm correct installation by checking that a known resistive load (1-2 kW) displays as an import in the inverter UI.

Inverter Settings for PCS

To maximize PCS performance, configure the following settings:

• Mode: Set to Self-Consumption / Priority Load.
• Export Limit: Set to Zero (non-export) or a specific kW/kVA cap as allowed by the utility.
• Grid Charge Windows (TOU): Configure to allow off-peak charging to raise State of Charge (SoC) for on-peak discharge.
• SoC Reserves: Maintain a UPS reserve (e.g., 20-40%) while enabling peak shaving above that level.

Troubleshooting

If the system is not behaving as expected, check the following:

• PCS blind to house loads: Ensure CTs are on the service conductors, not just the inverter feeder.
• Export shows as import: This indicates reversed CT polarity; flip the CT orientation.
• Generator back feed risk: Never allow export toward a generator; use an approved transfer switch/ATS and place CTs on load conductors.