Design and Evaluation of an IoT-Based Real-Time Energy Monitoring System Using NodeMCU and PZEM-004T

The increasing demand for accurate and affordable household electricity monitoring has driven the development of Internet of Things (IoT)–based systems. This study designed and evaluated a real-time energy monitoring system using a NodeMCU microcontroller integrated with a PZEM-004T sensor module. The system was tested on three household appliances, an electric iron, a fan, and a refrigerator, and its measurements were compared with a calibrated reference wattmeter and manual energy calculations. The results showed that the system’s readings closely matched those of the reference device, demonstrating reliable accuracy in capturing real-time energy consumption. Higher deviations were observed against manual calculations, mainly due to the inability of manual methods to capture dynamic load fluctuations, particularly from the refrigerator’s compressor. Overall, the system achieved an average error of 1.19% compared with the reference measurements, confirming its technical feasibility for practical household energy monitoring. Future work should improve accuracy for fluctuating loads through adaptive sampling and expand system scalability via cloud-based integration.