Konsumsi energi listrik yang tidak terpantau dapat menyebabkan pemborosan dan biaya listrik yang tinggi. Oleh karena itu, diperlukan sistem pemantauan energi listrik yang dapat memberikan informasi secara real-time kepada pengguna. Penelitian ini bertujuan merancang sistem pemantauan energi listrik berbasis web menggunakan sensor PZEM-004T dan mikrokontroler NodeMCU ESP8266. Sensor PZEM-004T mengukur tegangan, arus, daya, dan energi listrik, sementara NodeMCU ESP8266 mengolah serta mengirim data ke server. Sistem dikembangkan dengan PHP, MySQL, HTML, CSS, dan JavaScript. Metode penelitian meliputi perancangan perangkat keras dan lunak, serta pengujian pada beban listrik: resistif (setrika listrik), induktif (kipas angin), dan kapasitif (charger HP). Hasil menunjukkan setrika listrik memiliki daya 448.20 W hingga 454.00 W, kipas angin sekitar 40.50 W hingga 41.40 W dengan fluktuasi kecil, dan charger HP .10 W hingga 7.20 W dengan variasi arus yang lebih signifikan. Pemantauan dilakukan selama 5–25 menit dan sistem mampu memberikan informasi konsumsi energi secara real-time melalui antarmuka web.

Unmonitored electricity consumption can lead to waste and high electricity costs. Therefore, a real-time energy monitoring system is needed to provide users with accurate information. This study aims to design a web-based electrical energy monitoring system using the PZEM-004T sensor and NodeMCU ESP8266 microcontroller. The PZEM-004T sensor measures voltage, current, power, and energy consumption, while the NodeMCU ESP8266 processes and transmits data to the server. The system is developed using PHP, MySQL, HTML, CSS, and JavaScript. The research method includes hardware and software design, as well as testing on different electrical loads: resistive (electric iron), inductive (fan), and capacitive (phone charger). The results show that the electric iron consumes between 448.20 W and 454.00 W, the fan ranges from 40.50 W to 41.40 W with slight fluctuations, and the phone charger varies from 5.10 W to 7.20 W, with more significant current variations. Monitoring is conducted for 5 to 25 minutes, and the system successfully provides real-time energy consumption information through a web interface.