Evaluation of solar irrigation system under multipurpose use in the coastal region of Bangladesh

Abstract

Solar irrigation system has evolved as a green farming technology in areas of abundant irradiance. The challenge in Bangladesh is to make the technology affordable for marginal farmers. This study reports the results of a series of experiments carried out to evaluate the performance of solar irrigation pumps (SIPs) in the coastal region of Bangladesh. In this regard, field experiments were conducted on brinjal during the consecutive winter seasons of 2019-2020 and 2020-2021. A field survey on 24 diesel operated low lift pumps (LLPs) schemes and 6 electric AC pump schemes was carried out to estimate the suitable pump size for an average farmhouse in the coastal area. An SIP scheme with a solar pump (0.8 ​kW) was eventually developed to irrigate using three drips, and one furrow irrigation treatment. The experiment was laid out with a randomized control block design and was replicated thrice. Under the SIP schemes, drip irrigated plots produced higher average yields compared to the furrow irrigated plots. The best irrigation frequency under SIP was found to be 5 days under drip method considering the average solar irradiance in the coastal area. In order to emulate multipurpose use, a solar home system (SHS) was also developed receiving power stored from the SIP scheme at times when there was no need for irrigation. The financial evaluation showed that SIPs with multipurpose use could be a profitable investment when compared to LLPs, and electric AC pumps. The discounted benefit-cost ratio, and the internal rate of return for SIPs under multipurpose use were found to be 1.46 and 30% respectively. The break-even point of SIPs (0.80 ​ha) was found to be well within its command area (1.36 ​ha). This indicates that SIPs are a superior investment option for the existing diesel pump owners in the coastal area of Bangladesh and similar regions.