Optimal sizing of a grid-connected DC microgrid for agricultural applications with water-energy management system considering battery cycle life

This paper presents an optimal sizing method for a DC microgrid topology commonly installed in agricultural farms. The microgrid comprises solar photovoltaic (PV) panels, a battery energy storage system (BESS), an electric water pump, an elevated water reservoir (WR), and a household electrical load. The sizing optimization procedure includes selecting a suitable PV array size and optimizing the WR and BESS capacities. For the technical evaluation of possible solutions, a water-energy management system (WEMS) is proposed. Water is treated as an independent demand. The irrigation regime is modeled on the basis of farmers’ experiential knowledge and a temperature constraint to avoid unnecessary evaporation due to irrigation in high temperatures. Moreover, the battery cycle and calendar lifetimes are integrated into the presented sizing method. A case study is conducted for an actual farm with real data. Comparative simulations with alternative topologies show that the PV-BESS-Grid microgrid with solar water pumping is the most techno-economically efficient topology. The target farm, while supplied only from the grid, has a levelized cost of energy (LCOE) equal to 401 $/MWh. However, the presented sizing method finds a DC agricultural microgrid configuration that provides energy with an LCOE of 223 $/MWh. This is a significant 44% decrease in the LCOE. With the optimal solution, around 77% of the energy needs of the farm are supplied from renewable solar energy. In addition, wasted solar energy decreases by 62.4% compared to a standalone solar pumping system. Sensitivity analysis is performed by varying critical parameters to observe the impacts on the optimal solution.