Design and Installation of a Low-Cost Solar-Powered IoT Device for Ammonia Monitoring in Small Home Chicken Coops

Abstract

Ammonia from chicken manure is a common problem in small home poultry coops in crowded city areas, yet ready-made NH3 monitors cost IDR 1.5–5 million, far too much for a farmer who keeps five to ten hens. This paper describes how we designed, built and installed a monitoring device made from common parts for IDR 189,100 (about USD 12). The device uses an MQ-135 gas sensor, a DHT22 temperature and humidity sensor, a small LCD screen, an indicator LED and a buzzer, all controlled by a NodeMCU ESP8266. Power comes from a 2600 mAh Li-ion battery charged by a 5 V, 1 W solar panel. Two design choices make it different from earlier low-cost monitors. First, the MQ-135 heater is turned on and off by a P-channel MOSFET, so it can be switched off between readings to save power. Second, the ppm value is corrected using the temperature measured at the same moment, not a fixed value. Our calculation shows the device uses about 1,018 mAh per day, which means it can run for 61 hours with no sunlight. The device has been installed on a working coop with five laying hens in a crowded neighbourhood in Bandar Lampung. Testing the sensor against certified reference gas and running it for a long period are not covered here and remain to be done.