Performance Assessment and Design Recommendations of Nonisolated DC/DC Converters and Maximum Power Point Tracking Techniques for Standalone Photovoltaic Systems

Abstract

A maximum power point tracking (MPPT) algorithm is mandatory to operate the system at its maximum power point (MPP) under different irradiance and temperature for improved efficiency. This requires an impedance-matching mechanism in the form of a DC/DC converter between the photovoltaic (PV) modules and the load. Each MPPT algorithm and DC/DC converter governs the overall PV system performance differently. Published work in that regard is mainly analytical and narrative in comparing different DC/DC converters, in addition to being independent of MPPT methods. Unlike previous studies that treated MPPT techniques and DC/DC converter topologies in isolation or with limited integration, this paper offers a holistic cross-comparative analysis that systematically combines multiple MPPT algorithms with various converter architectures under a unified evaluation framework. This paper presents a comparative study of various nonisolated DC/DC converter topologies, including the step-down buck (linear but limited in tracking the MPP to low resistive loads), the step-up boost (continuous-energy-flow but limited to high resistive load MPP tracking), and the inverting step-up or step-down MPP load nonrestrictive buck–boost converters. These converters are explored with different MPPT techniques, primarily the perturb and observe (P&O) (simple, fast, and accurate but oscillatory), constant voltage (fast and relatively accurate), and power increment (capable of tracking global MPP [GMPP] but slow). Key findings of this study are verified in simulation and hardware experimentation and are summarized as follows: there is no universal optimal solution for PV systems with MPPT techniques and DC/DC converters. The MPPT choice depends on factors such as location, cost, implementation complexity, accuracy, and tracking speed. Ultimately, its the designer’s decision based on considerations of efficiency, complexity, loading limits, and capture zones for the chosen DC/DC converter. With quantified performance indices (PIs), verified results, and design recommendations, this work fills a critical gap in integrated MPPT-converter analysis and provides practical guidance in off-grid PV applications.