Solar sizing and battery state of charge tracking for low cost environmental monitoring in Uganda.

Abstract

The use of Wireless Sensor Networks in automated environment monitoring has grown significantly in the past decade because they are small, cheap and easily scalable compared to their traditional wired counterparts, which have dominated this area for a long time. The poor penetration of electric power grids requires battery-powered deployments, which must consume as little power as possible to maximize battery life in the short and long term. The effects of seasonal patterns and microclimate variations require the solar energy harvesting units (solar cells) to be sized using new data-driven techniques, because the traditional techniques may underestimate the required size by a large factor. As such, the techniques necessary to implement robust very low power WSNs are still very much open questions. To maximize battery life and prevent short-term failure, this study proposed several low power design guidelines. The study proceeded to compare various electrochemical energy storage technologies for WSN use cases. Lithium Iron Phosphate battery was chosen as the battery of choice for its superior performance over the other batteries. To improve the reliability of the network, there was a need to determine the state of charge the battery.