A grid-safe and efficiency-optimized architecture for next-generation photovoltaic string inverters under feed-in prevention and PV export conditions

The increasing penetration of photovoltaic systems in distributed energy networks has brought renewed attention to the persistent challenges of reverse power flow and voltage rise in low-voltage grids. Owing to uncertainties in grid infrastructure and stringent utility policies that restrict power injection, developing efficient inverter-level control architectures for reliable zero-export operation and enhanced PV utilization has become a pressing technical priority. However, most commercial string inverters lack embedded mechanisms for adaptive feed-in limitation, as their internal maximum power point tracking and control firmware are vendor-locked, preventing external intervention. To address this limitation, this study introduces a remote terminal unit -enabled feed-in prevention architecture that maximizes photovoltaic utilization while ensuring strict zero-export operation. The proposed system functions as an external supervisory controller that monitors real-time power flows and dynamically regulates inverter output through the Modbus interface, without any modification to the inverter firmware. Unlike conventional curtailment or battery-based systems, the architecture provides a low-cost and inverter-agnostic solution that maintains uninterrupted local load supply and stable inverter operation under varying irradiance and load conditions. Experimental validation on a 6 kW photovoltaic test bench demonstrates seamless transitions between maximum power point tracking and curtailment modes, consistent voltage stability, and full compliance with export limits. The results highlight a scalable, cost-effective, and field-deployable solution that serves as an efficient alternative to energy storage in export-controlled environments, paving the way for next-generation intelligent PV inverter architectures.