Transport Optimisation in Crystalline Silicon Photovoltaic Systems: Design, Fabrication, and Experimental Evaluation of a 60 A Maximum Power Point Tracking Charge Controller

Abstract

Photovoltaic energy conversion in crystalline silicon is governed by the nonlinear carrier transport properties of the p–n junction, whose current–voltage characteristic exhibits a distinct maximum power point (MPP) that shifts continuously with irradiance and junction temperature. Conventional pulse-width-modulation controllers cannot follow it and forfeit 20–30% of available energy. Well-characterised medium-to-high-current maximum power point tracking (MPPT) controllers designed for local fabrication are absent from the Nigerian technical literature; this work addresses that gap. A 60 A MPPT charge controller built on an asynchronous buck converter topology was designed, fabricated and evaluated. A Perturb and Observe algorithm runs on an Arduino Mega 2560, current is sensed through Hall-effect transducers that galvanically isolate the control stage from the power path, and five protection mechanisms guard against overvoltage, overcurrent, short circuit, reverse polarity and thermal runaway. Laboratory characterisation with a programmable PV-array emulator over 200–1000 W m⁻² yielded a peak power conversion efficiency of 95.8%, a peak MPPT tracking efficiency of 98.2% and an output voltage ripple of 0.67%, with a maximum MOSFET junction temperature of 76 °C at the rated 60 A load. Outdoor testing over five clear-sky days using two 250 Wₚ monocrystalline panels in series returned average conversion and tracking efficiencies of 94.8% and 97.5%. Every design decision is traced to its condensed matter basis. The results establish that locally fabricated controllers built from commercially available semiconductor components can match imported commercial units, lowering the cost barrier to off-grid photovoltaic deployment in sub-Saharan Africa.