Published February 16, 2026 © MIT

Smart Energy Bill Optimizer & Real-Time Power Monitor

An IoT device that tracks real-time power and reduces electricity bills. ⚡

BeginnerFull instructions provided8 hours1,119

Smart Energy Bill Optimizer & Real-Time Power Monitor

Things used in this project

Software apps and online services

Arduino IDE

Story

⚡ Introduction

Electricity bills are increasing every year, but most users still do not know:

How much power they are consuming right now

How much power they are consuming right now

Which appliance consumes more electricity

Which appliance consumes more electricity

How much bill will come before the billing cycle ends

How much bill will come before the billing cycle ends

Whether their load is safe or overloaded

Whether their load is safe or overloaded

Traditional electricity meters only show total units consumed. They do not provide real-time analytics.

To solve this problem, I developed a Smart Electricity Bill Saver + Real-Time Power Monitor using ESP32 and PZEM-004T energy monitoring module.

This IoT-based system provides real-time monitoring, bill estimation, overload detection, and cloud connectivity.

🔥 Problem Statement

Most homes and small businesses face:

❌ Unexpected high electricity bills❌ No real-time monitoring❌ No overload alert❌ No consumption analytics❌ No smart control

Without monitoring, energy waste continues silently.

💡 Proposed Solution

This project provides:

✔ Real-time Voltage Monitoring✔ Real-time Current Monitoring✔ Real-time Power (Watt) Calculation✔ Energy Tracking (kWh)✔ Live Electricity Bill Estimation✔ Overload Detection✔ MQTT Cloud Monitoring✔ Optional Auto Load Cut-off

🧰 Required Hardware

1️⃣ ESP32 (Main Controller)

Role:

WiFi connectivity

WiFi connectivity

Data processing

Data processing

MQTT communication

MQTT communication

Core system logic

Core system logic

ESP32 acts as the brain of the system.

2️⃣ PZEM-004T v3.0 Energy Monitor

Role:

Measures Voltage

Measures Voltage

Measures Current

Measures Current

Calculates Power

Calculates Power

Tracks Energy (kWh)

Tracks Energy (kWh)

The CT coil is installed on the AC phase wire.

3️⃣ 5V SMPS Power Supply

Role:

Provides stable DC power to ESP32 and relay module.

4️⃣ Optional Relay Module (Overload Protection)

Role:

Automatically cuts power if overload is detected.

🔌 Wiring Connections

ESP32 ↔ PZEM

TX2 → GPIO17

TX2 → GPIO17

RX2 → GPIO16

RX2 → GPIO16

VCC → 5V

VCC → 5V

GND → GND

GND → GND

CT Coil

Install on AC phase wire only.

Relay (Optional)

IN → GPIO4

IN → GPIO4

VCC → 5V

VCC → 5V

GND → GND

GND → GND

⚠ Always follow proper electrical safety standards while working with 220V AC.

⚙️ Working Principle

1️⃣ ESP32 reads voltage and current from PZEM2️⃣ Calculates real-time power (Watts)3️⃣ Tracks total energy consumption (kWh)4️⃣ Calculates estimated electricity bill5️⃣ Sends data to MQTT cloud6️⃣ Detects overload7️⃣ Cuts load (if relay connected)

Data updates every few seconds.

💰 Bill Calculation Formula

Energy (kWh) × Electricity Rate (₹ per unit) = Estimated Bill

Energy (kWh) × Electricity Rate (₹ per unit) = Estimated Bill

Example:

Energy consumed = 150 kWhElectricity rate = ₹6

Estimated bill = ₹900

The bill updates live in real-time.

📡 MQTT Topics Used

power/voltage power/current power/watt power/energy power/bill power/alert

power/voltage
power/current
power/watt
power/energy
power/bill
power/alert

These topics allow easy integration with web dashboards and mobile apps.

📊 Key Features

✔ Real-time monitoring✔ Instant bill estimation✔ Overload alert✔ Remote cloud monitoring✔ Low-cost solution✔ Scalable architecture

🏠 Applications

Residential homes

Residential homes

Shops

Shops

Offices

Offices

Hostels

Hostels

Solar systems

Solar systems

Small industries

Small industries

Energy audit services

Energy audit services

💼 Business Opportunity

This solution can be commercialized as:

Smart home product

Smart home product

Energy audit device

Energy audit device

Rental monitoring system

Rental monitoring system

Industrial load monitor

Industrial load monitor

IoT-based commercial product

IoT-based commercial product

Low cost + high awareness = strong market demand.

🚀 Future Enhancements

Android App Integration

Android App Integration

Web Dashboard with Graph

Web Dashboard with Graph

Monthly bill prediction

Monthly bill prediction

GSM alert system

GSM alert system

3-phase monitoring

3-phase monitoring

Smart appliance-level tracking

Smart appliance-level tracking

📞 Project Support & Custom Build

If you need:

✔ Complete Source Code✔ Web Dashboard✔ Android App✔ PCB Design✔ Ready Device✔ Commercial Deployment

📲 WhatsApp: +91 7052722734

Affordable solution available for students, developers, and businesses.

🏁 Conclusion

The Smart Electricity Bill Saver + Real-Time Power Monitor is more than just a monitoring device — it is a smart energy management solution.

It helps users:

✔ Reduce electricity bills✔ Track consumption✔ Improve efficiency✔ Prevent overload damage

A practical and scalable IoT solution for modern energy management.

Smart_Energy_Monitor_ESP32

Smart_Energy_Monitor_ESP32

C/C++

/*
====================================================
SMART ENERGY MONITORING SYSTEM USING ESP32 + PZEM

This code reads Voltage, Current, Power and Energy
from PZEM-004T sensor using ESP32.

Features:
- Calculates electricity bill (based on unit rate)
- Sends real-time data to MQTT broker
- Provides overload protection using relay
- Automatically cuts power if current exceeds limit
- Publishes system status and alerts via MQTT

Use Case:
Home / Industry Power Monitoring System
IoT Based Energy Meter with Remote Monitoring
====================================================
*/

#include <WiFi.h>
#include <PubSubClient.h>
#include <PZEM004Tv30.h>

const char* ssid = "YOUR_WIFI_NAME";
const char* password = "YOUR_WIFI_PASSWORD";

const char* mqtt_server = "broker.hivemq.com";
const int mqtt_port = 1883;

#define RELAY_PIN 4
#define PZEM_RX 16
#define PZEM_TX 17

float overloadCurrent = 10.0;
float electricityRate = 6.0;
bool relayState = true;

WiFiClient espClient;
PubSubClient client(espClient);
HardwareSerial pzemSerial(2);
PZEM004Tv30 pzem(pzemSerial, PZEM_RX, PZEM_TX);

void connectWiFi() {
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) delay(500);
}

void connectMQTT() {
  while (!client.connected()) {
    client.connect("PowerMonitorClient");
  }
}

void setup() {
  Serial.begin(115200);
  pinMode(RELAY_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, LOW);
  connectWiFi();
  client.setServer(mqtt_server, mqtt_port);
}

void loop() {

  if (!client.connected()) connectMQTT();
  client.loop();

  float v = pzem.voltage();
  float c = pzem.current();
  float p = pzem.power();
  float e = pzem.energy();

  if (isnan(v) || isnan(c)) return;

  float bill = e * electricityRate;

  client.publish("power/voltage", String(v,2).c_str());
  client.publish("power/current", String(c,2).c_str());
  client.publish("power/watt", String(p,2).c_str());
  client.publish("power/energy", String(e,2).c_str());
  client.publish("power/bill", String(bill,2).c_str());

  if (c > overloadCurrent) {
    digitalWrite(RELAY_PIN, HIGH);
    relayState = false;
    client.publish("power/alert", "Overload - Cut");
    client.publish("power/status", "OFF");
  } else if (!relayState) {
    digitalWrite(RELAY_PIN, LOW);
    relayState = true;
    client.publish("power/status", "ON");
  }

  delay(3000);
}