Design and Implementation of a Low-Cost IoT-Based Smart Energy Monitoring System

This paper presents the design and implementation of a low-cost IoT-based smart energy monitoring system for residential applications. The proposed system measures real-time voltage and current using dedicated sensors and computers instantaneous power and cumulative energy consumption using an ESP32 microcontroller. The architecture integrates an ACS712 Hall-effect current sensor, a resistive voltage divider network, an LCD display for local readout, and a Wi-Fi-enabled data transmission module. The system is evaluated across four representative household appliances an LED bulb, a ceiling fan, a laptop charger, and an electric heater spanning a power range from 10 W to 1000 W. Experimental results demonstrate that the system provides reliable monitoring with a mean absolute percentage error (MAPE) below 5% across all tested loads. The total hardware cost is kept under $15 USD, making the solution substantially more affordable than commercial smart meters. The proposed system offers a cost-effective, scalable, and user-friendly solution for improving residential energy awareness, which is a critical first step toward demand-side energy management.