Solar Sizing and Battery State of Charge Tracking for Low-Cost Environmental Monitoring in Uganda.

Abstract

Wireless sensor networks refer to a group of spatially dispersed sensors dedicated for monitoring and recording physical conditions of the environment and organizing the collected data at a central location. Sensor networks require a long lifetime and for these to be highly effective, reliable power supply is a necessity. The development of reliable solar systems that ensure the power supply never goes off for a given period (days of autonomy) is therefore one of the primary goals in solar system design yet the current options for solar system design have no protocol to demand what reliability the user expects. An optimal solar panel size that delivers sufficient energy for a given period is important for a highly reliable solar home system. The traditional technique of sizing solar photovoltaic (PV) panels involves the use of a blanket value of the expected hours of solar radiation in a given area and balancing it with the total load wattage. This does not take into consideration the microclimates which can cause similar systems to have different reliability performance when located in the same climatological zone. There is thus a need to improve the solar panel sizing for these systems. On the hand the energy obtained needs to be stored in a battery therefore choosing lithium Iron Phosphate Battery which has better characteristics and battery technology as compared to other batteries. This battery however doesn’t have an off the shelf battery state of charge monitoring device that can help track the battery percentage for a battery that has been deployed. This project therefore focuses on building a battery state of charge monitoring device for a LiFePO4 battery that is a rather new battery technology.