Design and implementation of efficient curve tracer for photovoltaic system under partial shaded conditions

Abstract

Photovoltaic (PV) panels are subjected to problems such as hot spots and reduced output power when operating in partially shaded conditions. Although bypass diodes are utilized to alleviate these problems, the diodes cause multiple-peak characteristics. Tracking the maximum output power in partially shaded conditions is difficult using conventional software-based maximum power point tracking (MPPT) techniques. Curve tracers can assist software-based MPPT to track the true/global maximum power point (MPP) by scanning several potential MPP areas. Therefore, a software-based MPPT with an I-V curve tracer is a preferred solution. Moreover, curve tracers reveal more about the PV array performance and the fastest method to do so. This paper investigates the advantages and disadvantages of several I-V curve tracers and proposes a load self-adaptive PV panel characteristic curve tracer by applying a hysteretic selfcontrolled duty-modulated load resistor (DMLR) to a boost converter I-V curve tracer. Several advantages are achieved such as simple structure, cost-efficient implementation and no tracing limitation near the Voc. A circuit for 72 W PV panel is used to verify the feasibility of the proposed curve tracer.