Open-Source Smart Wireless IoT Solar Sensor

This repository contains the source code (both software/firmware code and hardware schematics) for a smart wireless sensor that measures solar irradiance using a single small photovoltaic module that simultaneously serves as the energy harvester and sensing element.

The device integrates a low-power ESP32 microcontroller, a precision multi-channel ADC, and a programmable electronic load to sweep the PV I–V curve and estimate the MPPT. Irradi- ance is then computed from electrical power and the solar-cell temperature via a third-order polynomial derived from laboratory calibration and field data. The system supports multiple industrial and IoT protocols (Modbus RTU/TCP, MQTT, ZigBee), and operates either continuously from battery/seald lead-acid/Li-Po supplies or periodically from supercapacitors through sleep–wake cycles.

Hardware

You can find the schematics inside the schematics/ subdirectory. You will need Kicad to open them locally.

Software

ESP32 firmware used for the experiments can be found esp32-firmware/. It requires Platform IO to build and flash it onto the custom ESP32-based board.

The firmware communicates serially with a Python-based service that may be ran on a Raspberry PI.