A Solar Energy Harvester for a Wireless Sensor System toward Environmental Monitoring

Harmful environments can cause severe health problems to individuals. Thus, this study proposes a solar-powered wireless sensor system to monitor the physical parameters of an ambient environment in real-time. This system is developed based on two sensors and a NodeMCU board that includes a microcontroller with a Wi-Fi chip. This system is built to measure the ambient temperature, relative humidity, atmospheric pressure, and ultraviolet (UV) index. The power supply of the system is a solar energy harvester, which consists of a solar cell, a DC-DC converter, and a rechargeable battery. This harvester is practically tested outdoors under direct sunlight. The proposed system experimentally consumes an average power of 40 mW over one hour, and the lifetime of this system is 123 hours in the active-sleep mode. The results demonstrate that the system can sustainably operate for monitoring the environmental data.