Voltage-based dynamic string reconfiguration for enhanced power harvesting in partially shaded PV panels

Partial shading significantly degrades the performance of photovoltaic (PV) panels by creating electrical mismatches among series-connected strings, leading to substantial power losses. Conventional bypass diodes mitigate hotspot formation and reduce mismatch effects; however, they discard the useful energy that can still be generated by partially shaded strings. Although numerous dynamic reconfiguration techniques have been proposed, most focus on redistributing array connections while continuing to supply a single load, thereby limiting the utilization of power available from shaded strings. To address this limitation, this study proposes a voltage-based dynamic string reconfiguration strategy incorporating a secondary load for energy harvesting from shaded strings. The proposed method continuously monitors string voltages and calculates the voltage difference among PV strings. When the voltage mismatch exceeds a predefined threshold, the affected string is disconnected from the primary load and redirected to a secondary load through a matrix switching circuit, enabling simultaneous utilization of both shaded and unshaded strings. The technique was evaluated using MATLAB Simulink under 121 partial shading scenarios and experimentally validated using a 50 W PV panel under controlled irradiation conditions. Under severe partial shading conditions, the proposed method achieved a maximum power improvement of 61.7%, increasing the extracted power from 11.9 W to 19.3 W compared with the conventional bypass-diode configuration. Experimental results showed strong agreement with simulations, with a mean absolute percentage error of 2.55%, an RMSE of 0.89 W, and a maximum deviation below 5%. These results confirm the effectiveness of the proposed dual-load reconfiguration strategy for enhancing PV energy harvesting under partial shading conditions.