IoT Sensor Node for Solar Energy Measurements

This work presents the development of an Open Source Internet of Things (IoT) sensor node for solar radiation measurements, designed for expansion into a sensor network. The system utilizes a Raspberry pi 5 with an attached hardware module (HAT) for current monitoring which incorporates four INA219 sensors, and an environmental sensor BME280. Making use of two different solar cells, the current output of the panels as well as the voltage drop across a shunt resistor is measured with the help of INA219. These measurements are logged to a time series database, namely InfluxDB. Data visualization is supported by a locally hosted instance of Grafana (open source). In addition, the BME280 sensor logs the enclosure temperature values. A dataset of current, voltage and temperature values is created. Using the open source solar modeling tool pvlib and the readings from the two solar cells, the system estimates the global horizontal irradiance using linear regression.