IoT-Based Electrical Power Monitoring and Control using NodeMCU and PZEM-004T for Energy Management in Small-Scale MSMEs

Abstract

Efficient monitoring and management of electrical energy are important for small-scale micro, small, and medium enterprises (MSMEs). Conventional prepaid electricity monitoring requires users to inspect the meter directly, which is less practical for continuous monitoring. This study presents the design and implementation of an Internet of Things (IoT)-based electrical power monitoring and control prototype using a NodeMCU/ESP32 controller and PZEM-004T sensor. The system measures voltage, current, power, energy, frequency, and power factor, displays data locally through an I2C LCD, accepts prepaid-energy top-up input through a 4×4 keypad, and controls the electrical load using a relay. Blynk is used for real-time remote monitoring. Top-up values in Indonesian rupiah are converted into kWh using a fixed electricity tariff, while the energy balance is reduced according to measured consumption. Tests were performed by comparing the prototype with a digital watt meter and by evaluating top-up, balance reduction, relay control, and Blynk monitoring functions. The prototype successfully displayed electrical parameters in real time. At 60 min, the prototype measured 234.4 V, 0.2 A, 22 W, and 0.022 kWh, while the reference watt meter measured 232.4 V, 0.175 A, 21 W, and 0.021 kWh. The reported maximum errors were 1.52% for voltage, 14.29% for current, 6.28% for power, 10.00% for energy, 15.69% for power factor, and 0% for frequency. Top-up and relay-control tests were successful, and the five principal functional tests achieved a reported 100% success rate.