Development of a Microcontroller-Based Relaying System for Grid-Connected Photovoltaic Systems for Small Appliance Loads

Abstract

The use of photovoltaic (PV) cells to convert solar irradiation is one of the most popular forms of renewable energy utilization and improvements in the existing technologies has been one of the focus of various research studies. The implementation of photovoltaics for the study mainly focused on the use of PV system as a grid-tied element which served as the primary power supply for small appliance loads during loaded operation with the grid providing the backup supply in the case that the PV system failed to provide sufficient power. Such was the case when (a) sunlight is not sufficient to energize the load, (b) the energy storage unit, which is the battery, had insufficient charge, or (c) the current generated by the PV modules is less than the current through the load. These factors were monitored through the monitoring and control system elements of the design which also performed the necessary supply switching for the conditions of the system while also monitoring the energy consumed from the grid and energy delivered back to the grid. Through the system created, power generated by the PV modules was delivered to the load or fed to the grid, and load was shifted back to the grid, as necessary. The responses of the relay were the most suggestive of the effective implementation of the design. The responses recorded were of high accuracy and high precision in nature as tested for dependence through analysis of binary data by comparing the occurrence of expected outcome and actual observed outcome.