Improving electrical performance of reliable solar-powered irrigation system

Abstract

A solar-powered irrigation system has been developed to address the lack of affordable irrigation solution for the marginal farmers in India. An MIT spinout, Khethworks, has designed an efficient water pump with low power rating, and created a low-cost irrigation system with the pump, a photovoltaic panel, and a battery. This thesis analyzes the electrical properties of such a configuration, and determines whether implementing maximum power point tracking (MPPT) can improve the system's performance. This is accomplished through modeling and conducting a system-level simulation. The amount of electrical energy generated by the photovoltaic panel and the amount of water delivered by the pump are chosen as the key measures of the system's performance. The simulation result indicates that implementing MPPT with the current version of the Khethworks irrigation system - using lower-power panels of the 48 or 60 cell variety - would not significantly increase its performance. However, an irrigation system with higher power rating (e.g., a 72-cell panel, such as with a 320 W rating) would significantly benefit from the MPPT, and the MPPT's benefits are consistent over the variation in location and time. Based on the finding, we identify circumstances under which each of the direct load line and the maximum power point tracking approaches are preferable, and recommend an action plan to Khethworks accordingly.