Design and Fabrication of a 3-D Printed Concentrating Solar Thermoelectric Generator for Energy Harvesting Based Wireless Sensor Nodes

This letter presents the design of a solar thermoelectric generator (STEG) system for long-range wireless sensor networks in precision agriculture applications. The proposed STEG consists of a sunlight concentrator structure integrated with a Fresnel lens and a commercial thermoelectric module that is adapted to an energy harvester circuit and a wireless sensor node. The STEG is assembled using an inexpensive 3-D printed structure that can be mechanically adjusted to different sun exposure conditions. The proposed STEG prototype has been fabricated and tested. Measurement results demonstrate the STEG's capability of generating a maximum temperature difference of 60 °C between the hot-side of the thermoelectric module and the heatsink attached to the cold-side, with a maximum instantaneous output power of 6.93 mW. Charging a 0.22 F supercapacitor, the STEG supplies enough energy in approximately 2.2 h to sustain the operation of a wireless sensor node that measures soil temperature, humidity, and conductivity for precision agriculture applications. This letter presents a promising, cost-effective new approach to the conversion of solar energy into electricity for self-powered sensor networks.