An Energy-Harvesting Shield and Solar Testbed for IoT: LoRa Performance Insights and Power Measurements

Designing firmware for energy-harvesting (EH) IoT devices requires testing under realistic and repeatable conditions, yet most simulation tools abstract away critical physical constraints, and field testing is often impractical or non-reproducible. This paper presents a two-part platform to address this challenge: (i) a modular shield for the STM32 NUCLEO development boards that integrates a solar panel, energy harvesting power management, environmental and motion sensors, GPS, and flash memory; and (ii) an indoor testbed that reproduces real-world solar irradiance using programmable dimmable lamps driven by recorded sunlight traces. Together, these tools enable reproducible experimentation on energy-aware firmware, including runtime adaptation and energy budgeting strategies. Furthermore, we analyze real-world LoRa communication performance and highlight a lesser-known phenomenon where higher spreading factors, while theoretically robust, experience signal degradation due to synchronization loss. Our platform provides a practical foundation for long-term, realistic evaluation of EH-powered IoT systems.