Aggregate Modeling of Behind-the-Meter Solar Photovoltaic Systems and Defining Critical Penetration Thresholds for Distribution Fault Studies

The increasing adoption of behind-the-meter (BTM) solar photovoltaic (PV) systems in electric distribution networks has raised questions about their impact on fault analysis. Traditional fault studies often omit the contributions of distributed BTM PV generation, potentially introducing inaccuracies in fault current calculations and complicating protection coordination. This study investigates whether there exists a critical PV penetration threshold, defined as a percentage of total system load, beyond which BTM PV contributions significantly affect fault current levels. A range of PV penetrations is evaluated using both dynamic and static PV fault models, and composite load aggregation techniques are examined as a means to simplify model complexity. Detailed simulations using OpenDSS on the IEEE 8500 Node Test Feeder reveal that BTM PV has a minimal effect on primary-side fault currents, even at high penetration levels. As a result, strict modeling of BTM PV in distribution fault studies may not be necessary for most planning scenarios. Additionally, simple aggregation methods are shown to reduce model complexity and simulation time without compromising accuracy for static simulations. These findings can help utilities streamline fault study practices even as BTM solar deployment continues to grow.