Design of Buck-Boost Converter as Battery Charger on AC Power Usage Based on 20W Solar Cell

An automatic battery charging system has been designed using the Buck-Boost Converter (BBC) method based on a 20W solar cell with AC power output that can be monitored and controlled using a Smartphone. The main objective of this research is to create a stable charging system for the battery using energy sources generated from the sun, and to maintain the voltage on the battery so as not to overcharging or undercharging. The results of this study indicate that the automatic charging system on the battery has been created successfully, with the working principle of automatic cut off on the battery when the voltage reaches 14.2 V and cut off the power output on the load when the battery voltage is below 12 V. The BBC circuit is able to stabilize the input voltage from the panel to 16 V. Then it is regulated by the LM 317 regulator to 14.2 V. The LM 317 circuit which is connected to the battery through a relay is able to limit the battery voltage so that it does not exceed 14.2 V. This system is controlled by the Arduino Uno microcontroller. The data in this study is displayed on an LCD and sent to the user via the internet by IoT. Charging and output from the battery to the inverter can be controlled and monitored using the Blynk application on the Smartphone. The output of this system is a 220 V AC voltage source which is inverted by a 12 V DC – 220 V AC inverter