This study proposes a control-integrated architecture for a Fully Parallel Embedded Z-Source Inverter (FPEZSI) with a Quad-Leg topology, designed for Flexible Photovoltaic (FPV) systems in low-voltage four-wire distribution networks. The inverter addresses critical power quality challenges under distorted grid conditions and non-linear, unbalanced loading. Its topology incorporates two isolated DC sources—typically PV arrays—within an X-shaped impedance network, ensuring continuous DC input current and eliminating the need for bulky LC filters, thereby improving system compactness and cost-efficiency. The Quad-Leg configuration enables full neutral current compensation, essential for unbalanced four-wire grids. A corrected p-q control strategy is developed to support multifunctional operation, including Maximum Power Point Tracking (MPPT), Active Power Filtering (APF), and DC bus voltage regulation. This unified control approach allows simultaneous energy extraction, harmonic mitigation, and voltage stabilization. Performance evaluation under distorted voltage and asymmetrical load conditions confirms the inverter’s dynamic stability and harmonic suppression capabilities. The system achieves a boost factor of B=1.8 at a modulation index of D=0.3, maintains a stable DC link voltage at VC=550 V, and reduces source current Total Harmonic Distortion (THD) to 0.81%, significantly outperforming the IEEE 519 standard threshold of 5%. These results validate the FPEZSI’s reliability, scalability, and suitability for smart grid integration and advanced energy management, particularly in distributed renewable environments requiring robust power quality and multifunctional inverter control.