Automated Solar LED Street Light with LDR Daylight & PIR Motion Dimming

Rural street lighting installations often deplete battery reserves before dawn. This smart solar luminaire switches on at dusk via an LDR Light Dependent Resistor, operating at an energy-saving 20% standby glow until the HC-SR501 PIR Motion Sensor detects pedestrians, ramping up to 100% brightness via an IRFZ44N Power MOSFET.

Hardware Bill of Materials (In Stock at Ghumti Pasal):

• Microcontroller: Arduino Nano V3.0 Solderless (Without Cable)
• Light Sensor: LDR Light Dependent Resistor 5mm Photoresistor Sensor Module
• Motion Sensor: HC-SR501 Adjust IR Pyroelectric Infrared PIR Module
• PWM Switch: IRF Z44N N-Channel Power MOSFET
• Battery Charging: Type C 5V 1A 18650 TP 4056 Lithium Battery Charger Module
• Battery: 18650 3.7V 3000mAh Lithium-Ion Battery

Circuit Pinout & Wiring Connections:

Arduino Control Code:

const int ldrPin = A0;
const int pirPin = 2;
const int mosfetPin = 9;

const int duskThreshold = 400; // Calibrated for evening twilight

void setup() {
  Serial.begin(9600);
  pinMode(pirPin, INPUT);
  pinMode(mosfetPin, OUTPUT);
  analogWrite(mosfetPin, 0);
}

void loop() {
  int lightLevel = analogRead(ldrPin);
  bool motionDetected = digitalRead(pirPin);

  if (lightLevel > duskThreshold) { // Nighttime
    if (motionDetected) {
      analogWrite(mosfetPin, 255); // 100% Full High Beam
      delay(15000); // Keep illuminated for 15 seconds
    } else {
      analogWrite(mosfetPin, 50);  // 20% Energy Saving Standby Glow
    }
  } else {
    analogWrite(mosfetPin, 0);    // Daytime Off & Charging
  }
  delay(200);
}