Programmable photovoltaic submodules for hotspot mitigation

Abstract

This paper introduces a novel approach to conventional Photovoltaic (PV) modules that involves regulating the internal connections of the PV strings (or submodules) using a set of switches to isolate shaded submodules while leaving unshaded submodules unaffected. By extending the connection types of the PV submodules to include parallel or series via an external circuit, along with a set of switches, the output voltage and current can be adjusted without requiring additional PV modules to increase the output current. A microcontroller is employed to control the connections of the PV submodules to achieve three modes: series connection, parallel connection, or mixed connection. As a result, there is no need for a buck-boost converter, and the effects of partial shading are minimized, while the hotspot effect is mitigated without bypass diodes. A Matlab/Simulink model is utilized to validate the proposed configurations, and two customized hardware PV modules are fabricated to represent the conventional module and the proposed module. The results obtained from the hardware implementation support the concept of separating shaded PV submodules and regulating the internal connections of the submodules in different configurations. This feature of separating the unshaded submodules is implemented to enhance the efficiency of the PV modules.