Power Optimization of Solar Powered Standalone Wireless Sensor System

Abstract

Wireless sensor systems are common in applications where harsh environmental conditions or remote locations make it difficult to run wires. Having these sensor systems self-powered is essential as it is difficult for battery replacement. Using solar as an alternative source of energy can be a medium to charge the battery in such scenarios. With an increasing number of portable devices powered by battery; more and more research is focused on low-power design technique. For this thesis, a microcontroller (Texas Instruments MSP432) was used along with a digital sensor (Bosch BME280) to provide temperature, pressure and humidity information, and Wi-Fi module (Espressif ESP8266) to transmit the information to the Internet where it was posted to a spreadsheet on a web server. Power levels were measured with different modes in order to compare the power consumption of the MSP432. In addition, a solar charging circuit was designed to provide management of a Lithium-ion battery to explore the feasibility of operating this Internet connected sensor system entirely off the power grid. Incremental steps were taken to reduce the power consumption by the system and a system was designed to run with the lowest power consumption. The power requirements for each component connected to the microcontroller were calculated and then optimized. The minimum current required during transmission was reduced by 25.71%. A 2000mAh battery was selected for the final design to maintain system operation during extended dark hours. Solar panels were able to charge the battery whenever sunlight was available with the intent to keep the system running continuously on battery power. The system was tested for 20 days, and it ran without any interruption