This project creates a self-powered PIR motion sensor that runs entirely on solar energy. It’s ideal for remote locations where running power cables or changing batteries is impractical. The system stores energy in a supercapacitor or rechargeable battery, providing operation through the night.<\/p>\n
Difficulty:<\/strong> Advanced A small solar panel charges a supercapacitor or lithium battery during the day. An ultra-low power PIR sensor (Excelitas PYD 2597 or Panasonic EKMB) draws only 2-6 \u00b5A, allowing continuous operation. When motion is detected, the system wakes a microcontroller to process the event and optionally transmit via low-power radio (LoRa, Zigbee, or Bluetooth).<\/p>\n Component power consumption:<\/strong><\/p>\n With 10 events\/day:<\/strong> 0.216 mAh + (15 mA \u00d7 0.5s \u00d7 10 \/ 3600) = 0.216 + 0.021 = 0.237 mAh\/day<\/p>\n With 1000 mAh battery:<\/strong> 1000 \/ 0.237 \u2248 4,200 days \u2248 11.5 years!<\/p>\n But battery self-discharge limits practical life to 2-3 years. Solar charging extends indefinitely.<\/p>\n For continuous operation without battery, you need enough solar power to cover daily consumption:<\/p>\n A 50x50mm solar panel is sufficient for most locations.<\/p>\n This energy-harvesting PIR sensor provides maintenance-free operation in remote locations. With proper design, it can operate indefinitely without battery changes.<\/p>\n","protected":false},"excerpt":{"rendered":" Project Overview This project creates a self-powered PIR motion sensor that runs entirely on solar energy. It’s ideal for remote locations where running power cables or changing batteries is impractical. The system stores energy in a supercapacitor or rechargeable battery, providing operation through the night. Difficulty: Advanced Estimated time: 4-6 hours Estimated cost: $40-60 How […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-3908","post","type-post","status-publish","format-standard","hentry","category-projects"],"blocksy_meta":[],"yoast_head":"\r\n
\nEstimated time:<\/strong> 4-6 hours
\nEstimated cost:<\/strong> $40-60<\/p>\nHow It Works<\/h2>\n
Materials Needed<\/h2>\n
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Circuit Diagram<\/h2>\n
Power Management Section<\/h3>\n
\nSolar Panel (+) --- Schottky Diode ---+--- TP4056 IN (if using battery)\n |\n +--- Supercapacitor (+) (if using cap)\n |\n +--- LDO (MCP1700) IN\n |\nSupercapacitor\/Battery (-) ------------+--- LDO GND\n |\nLDO OUT (3.3V) ------------------------+--- PIR VCC\n +--- MCU VCC\n<\/pre>\n
Sensor Connection<\/h3>\n
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Component<\/th>\n Pin<\/th>\n MCU Pin<\/th>\n<\/thead>\n \nPIR Sensor (PYD 2597)<\/td>\n VCC<\/td>\n 3.3V<\/td>\n<\/tr>\n PIR Sensor<\/td>\n GND<\/td>\n GND<\/td>\n<\/tr>\n PIR Sensor<\/td>\n OUT<\/td>\n GPIO (with pull-up resistor 10k to 3.3V)<\/td>\n<\/tr>\n PIR Sensor<\/td>\n WUP (wake-up)<\/td>\n GPIO (interrupt pin)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Arduino Code (ESP32-C3 with Deep Sleep)<\/h2>\n
\/\/ Energy Harvesting PIR Sensor\n\/\/ Uses ESP32-C3 with deep sleep and wake-on-interrupt\n\n#include <esp_sleep.h>\n\n\/\/ Pin definitions\nconst int pirPin = 4; \/\/ PIR output\nconst int wakePin = 5; \/\/ PIR wake-up pin (optional, if separate)\nconst int ledPin = 8; \/\/ Status LED (optional)\n\n\/\/ Battery monitoring (voltage divider)\nconst int batteryPin = 3; \/\/ ADC pin with voltage divider (1M + 2M)\n\nRTC_DATA_ATTR int eventCount = 0; \/\/ Store across deep sleep\nRTC_DATA_ATTR unsigned long lastWakeTime = 0;\n\nvoid setup() {\n Serial.begin(115200);\n \n pinMode(pirPin, INPUT);\n pinMode(ledPin, OUTPUT);\n \n \/\/ Check why we woke up\n esp_sleep_wakeup_cause_t wakeup_reason = esp_sleep_get_wakeup_cause();\n \n if (wakeup_reason == ESP_SLEEP_WAKEUP_EXT0) {\n \/\/ Woken by PIR motion\n Serial.println(\"Wake-up: Motion detected\");\n \n \/\/ Blink LED to indicate detection\n digitalWrite(ledPin, HIGH);\n delay(500);\n digitalWrite(ledPin, LOW);\n \n \/\/ Increment event counter\n eventCount++;\n \n \/\/ Send notification (if radio available)\n sendNotification();\n \n \/\/ Record wake time\n lastWakeTime = millis();\n \n } else if (wakeup_reason == ESP_SLEEP_WAKEUP_TIMER) {\n \/\/ Periodic wake-up for battery reporting\n Serial.println(\"Wake-up: Timer (battery check)\");\n reportBattery();\n }\n \n \/\/ Go back to sleep\n goToSleep();\n}\n\nvoid sendNotification() {\n \/\/ If using LoRa, send packet here\n \/\/ If using BLE, advertise connection\n \n Serial.print(\"Motion detected! Total events: \");\n Serial.println(eventCount);\n \n \/\/ Simulate transmission (actual implementation depends on radio module)\n \/\/ This would normally take 50-200ms\n delay(100);\n}\n\nvoid reportBattery() {\n \/\/ Read battery voltage through voltage divider\n \/\/ Assuming 1M + 2M divider: Vbat = Vread * (1M+2M)\/2M = Vread * 1.5\n int raw = analogRead(batteryPin);\n float voltage = (raw \/ 4095.0) * 3.3 * 1.5; \/\/ 3.3V reference, 1.5x divider factor\n \n Serial.print(\"Battery voltage: \");\n Serial.println(voltage);\n \n \/\/ Could send via LoRa here\n}\n\nvoid goToSleep() {\n Serial.println(\"Entering deep sleep...\");\n delay(100);\n \n \/\/ Configure wake-up on PIR interrupt (HIGH level)\n esp_sleep_enable_ext0_wakeup((gpio_num_t)pirPin, 1); \/\/ Wake on HIGH\n \n \/\/ Also wake every 24 hours to report battery\n esp_sleep_enable_timer_wakeup(24 * 60 * 60 * 1000000ULL); \/\/ 24 hours in microseconds\n \n \/\/ Deep sleep\n esp_deep_sleep_start();\n}\n\nvoid loop() {\n \/\/ Not used - all code in setup()\n}\n<\/code><\/pre>\nPower Budget Calculation<\/h2>\n
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Solar Panel Sizing<\/h2>\n
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Enclosure Design<\/h2>\n
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Installation Steps<\/h2>\n
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Project Extensions<\/h2>\n
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Troubleshooting<\/h2>\n
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Conclusion<\/h2>\n