The problem of low power factor in household electrical installations can lead to reduced energy efficiency. This condition is generally caused by the dominance of inductive loads without adequate reactive power compensation. Therefore, a system capable of automatically monitoring and correcting the power factor is needed to maintain power quality and improve energy efficiency, particularly in residential settings with a 2200 VA supply. This study was conducted by designing an automatic power factor monitoring and correction system using an ESP32 microcontroller and a PZEM-004T sensor. The system is equipped with a capacitor bank consisting of four 20 uF capacitors, which are automatically controlled via relays based on the measured power factor. Electrical data are displayed on an I2C LCD, and the system provides an audible warning via a buzzer if the power factor falls below a specified threshold. Test results show that the system is capable of significantly improving the power factor, from an initial range of 0.64-0.76 to 0.83-0.99 after activating the capacitor bank, approaching the ideal value of 1. The average measurement error of the PZEM-004T sensor compared to a reference instrument was below 4%, namely about 2% for voltage, 2% for current, 2% for active power, 0.3% for frequency, and 0.4% for power factor. In addition, the system also recorded an increase in the measured active power as well as an improvement in apparent power efficiency of up to 27.9%, 32.7%, 26.1%, and 24.7% across the four tested load conditions. With its capability to monitor electrical parameters in real-time and perform effective automatic compensation, the system is considered suitable for application in household installations to improve energy consumption efficiency, reduce power losses, and maintain overall power quality.
Keywords: power factor, ESP32, PZEM-004T, capacitor bank, energy efficiency, automatic monitoring