DESIGN AND CONSTRUCTION OF A SOLAR CHARGE CONTROLLER

Abstract This project focuses on the design and construction of a 12V, 60A solar charge controller for regulating voltage from photovoltaic (PV) panels to rechargeable batteries. The increasing global energy demand and depletion of fossil fuels necessitate efficient utilization of renewable energy sources, particularly solar power. However, solar panels often produce voltages exceeding battery ratings, leading to overcharging and battery damage. To address this problem, a solar charge controller was developed using Maximum Power Point Tracking (MPPT) algorithm and a series feedback voltage regulator. The system incorporates a microcontroller unit (MCU), voltage and current sensors (ACS712), relays, and voltage regulators (LM7805, LM7812) to maintain stable output. The controller automatically switches between solar panel and rechargeable battery sources, prevents reverse current flow, and protects against overcharging, overheating, and overcurrent. Testing was conducted between 10:30 AM and 4:30 PM, showing no-load voltage of 14–15V and on-load voltage of 11–13V at the charger output, with load current ranging from 0.8A to 2.5A. The MPPT-based design achieved approximately 95% efficiency. A 220Ah lead-acid battery provided approximately 10 hours of backup. The final device successfully regulates voltage to meet mobile phone and battery charging requirements (13.7V, 4A). The project demonstrates a low-cost, high-efficiency solution for small-scale solar power applications, particularly in regions with unreliable grid electricity. **Keywords:** Solar charge controller, MPPT, voltage regulation, battery protection, renewable energy, PWM, photovoltaic system.