Control for the Substring-MPP-Tracker

Abstract

The substring MPP tracker is a power electronic circuit that increases the yield of partially shaded photovoltaic modules. The connection occurs directly in the junction box of the photovoltaic module. During the event of shading, the substring MPP tracker prevents bypass diodes from conducting and enables the maximum possible power extraction at the substring level. The previous control of the power electronics is based on voltage control of the substring voltages and current adjustment with maximum power point tracking. Parasitic effects lead to deviations from the actual maximum power point voltages in different shades. This report therefore presents a new feedback-based control method for the substring MPP tracker. This is based on voltage control with feedback of the substring voltages and current adjustment with maximum power point tracking. Measurements at a laboratory-scale test setup demonstrate the functionality of the voltage control. In case of partial shading of the module of the test setup, the feedback-based voltage control we present raises output power up to 2.59% compared to the previous voltage control.