Hardware Capacity Enhancement and Thermal Performance Optimization of an MPPT Solar Charge Controller for Stand-Alone Photovoltaic Systems

Abstract

The operational efficiency and service life of stand-alone solar photovoltaic (PV) systems are critically governed by the performance of the charge controller. However, conventional Maximum Power Point Tracking (MPPT) charge controllers deployed in decentralized installations frequently encounter hardware bottlenecks, including excessive thermal dissipation in switching semiconductors, elevated conduction losses, and limited current-handling capability under scaled array capacities. This study presents the design implementation and empirical performance evaluation of targeted hardware enhancements applied to an MPPT solar charge controller. The modifications comprise: (i) an upgraded toroidal inductor within the DC–DC converter stage to reduce current ripple and prevent magnetic saturation, (ii) the integration of a power MOSFET with lower on-state resistance (RDS(on)) and higher breakdown voltage, (iii) an enlarged heatsink profile, and (iv) an active 12 V DC cooling fan regulated via a temperature sensor with hysteresis control. Field experiments were conducted under outdoor irradiance conditions using three PV configurations: 2 × 80 W panels in series, 2 × 180 W panels in series, and a combined 4-panel parallel-series array connected to a 12 V, 220 Ah tubular lead-acid battery. Experimental results showed that the controller’s average energy conversion efficiency increased from 67.70% under the 2 × 80 W baseline to 89.24% under the 2 × 180 W configuration. Thermal evaluation confirmed that the active cooling mechanism reliably prevented thermal runaway and stabilized operating temperatures under high-load conditions without incurring parasitic losses at low loads. Battery charging assessments verified practical field viability, requiring approximately 22 effective solar charging hours from a 50% state-of-charge. These findings demonstrate that targeted component-level upgrades provide a cost-effective route to enhancing the reliability, capacity, and energy harvest of solar charge controllers in resource-constrained environments.