Estimation of surplus energy in off-grid solar home systems

Abstract

A recent survey shows that a large percentage of people living in underdeveloped countries do not have access to electricity and are isolated from the rest of the world. Solar energy can help meet the energy demand; however, it has an intermittent nature and relatively high installation cost. The improvement in off-grid Solar Home Systems (SHS) helped many people get access to electricity. However, systems are sized to meet demand on cloudy days, which results in significant wastage of available energy on sunny days, reducing the energy return on investment. This research paper discusses the load requirement of the people living in rural locations. It uses data collected over the last year by collaborating organisations, providing detailed load and solar charging data for off-grid households in Odisha, India. This dataset is analysed to understand the working principle of the installed SHS and the typical daily load profile. Next, the solar data is compared with solar data from online accessible software on an hourly basis and on a 5-minute scale to evaluate the surplus energy. The data shows a significant surplus of solar energy for most of the year that could be used for other low-powered devices. Various methods are discussed to detect surplus energy available during the daytime based on the provided solar data.