Solar PV powered micro irrigation systems for Sri Lanka : a case study

Abstract

The escalating global population and diminishing natural resources have underscored the critical need for efficient water and energy management. Advancing technological solutions have become imperative to curb resource overuse and optimize utility, especially within the agricultural sector, where water and energy play pivotal roles. Contemporary agricultural practices increasingly rely on innovative technologies aimed at fostering sustainable resource management. In rural agricultural regions, where access to conventional energy infrastructure is often limited solar powered micro irrigation systems have emerged as a viable and efficient alternative for addressing these challenges, enabling judicious water and energy usage. This research focuses on evaluating the feasibility of implementing solar photovoltaic (PV)- powered micro irrigation systems in Sri Lanka’s agricultural landscape. The study primarily explores existing technological approaches documented in the literature related to solar-assisted micro irrigation. To identify the most appropriate system, qualitative data were collected through field visits and stakeholder interviews, assessing operational requirements and challenges. The investigation identified drip and sprinkler irrigation systems integrated with solar PV-powered direct current (DC) submersible pumps as the most technically suitable configurations. A case study was conducted on a farm in Matale, located in Sri Lanka’s Central Province, to assess the techno-economic viability of the selected systems. Spanning a period from 2021 to 2022, the research entailed comprehensive data collection, including solar irradiance levels, pump performance metrics, crop yield data, and economic returns. Results showed that the drip irrigation system delivered a 52.82% increase in onion yields compared to the sprinkler system (11,920 kg vs. 7,800 kg per 0.5 acre). The economic analysis affirmed the strong financial feasibility of these systems. When subsidized, the combined irrigation setup achieved a Net Present Value (NPV) of $15,391.71, with a payback period of 3.5 years. Notably, the drip irrigation system alone yielded an NPV of $9,969.21 and a shorter payback period of 3.08 years. Operationally, the solar pumping system demonstrated 85% reliability during cultivation periods, adequately meeting irrigation demands on the majority of days. Furthermore, the Levelized Cost of Energy (LCOE) for solar pumping was calculated at $0.21/kWh, significantly lower than the $0.47/kWh cost associated with kerosene-based pumps. The findings of this research highlight the considerable promise of solar PV-powered micro irrigation systems for Sri Lanka’s small- and medium-scale agricultural enterprises, presenting a sustainable solution for resource conservation and income enhancement. The study advocates for the prioritization of government subsidies toward drip irrigation technologies to amplify agricultural output and promote energy sustainability.