Comparative assessment of a stand-alone and a grid-connected hybrid system for a community water supply system: A case study of Nankese community in the eastern region of Ghana

Abstract

Community water supply systems in Ghana are grid connected which is intermittent leading to breakdown of the systems and causing water shortages. In addition, high electricity tariffs have led these systems into huge debts. This research, therefore, aims to conduct comparative assessment of adopting a hybrid grid-connected and a stand-alone power system for these systems, using HOMER pro software. A daily average of 121.25 kWh was obtained from the chosen site as an input. Two scenarios were considered: a Grid-PV (Scenario 1) and a PV-Genset (Scenario 2) hybrid systems. The grid-connected (Grid-PV) was the best option with a LCOE of $0.0824/kWh while the standalone (PV-Genset) system was $0.309/kWh. Comparing them with $0.233/kWh for the Grid-only system, the Grid-PV system was about 184% cheaper while the PV-Genset system was about 24% more expensive. The PW of the scenarios yielded $58,422 and -$43,371, an IRR of 15.3% and 1.6% and a SPP of 6.21 and 24.13 years respectively. Although Scenario 1 was economically viable for investment, it yielded the highest GHG emission of 12,341.5kg/yr. Scenario 2, on the other hand, was not an economically viable option but yielded the least GHG emission of 4775.57kg/yr. Although this system was relatively expensive from the financial point of view, environmental considerations together with the grid tariff evolution in its life-cycle will make it cheaper.