Multi-Objective Optimization of Microgrid Sizing Integrating a Water Heating System under a Tranche Electricity Tariff

This paper addresses the optimal sizing of a water heating system powered by a microgrid integrating photovoltaic (PV) panels and an energy storage system. The problem is formulated as a multi-objective optimization with constraints, based on hot water consumption data and weather conditions over one year. The objectives aim to reduce: (i) energy and investment costs, (ii) CO2 emissions, and (iii) user dissatisfaction. Decision variables include the number of PV panels, batteries, and the type and number of electric water heaters. The problem is solved using the multi-objective PSO algorithm. A tiered pricing system, common in North Africa, is used to calculate bills. Two comparisons are conducted to evaluate the performance of the proposed solution: one against the industrial solution (Homer software) and another against the conventional solution (without the use of energy storage systems). The first comparison indicates a 42.9% reduction in total costs, along with an 84.7% decrease in the investment and maintenance (IM) costs of the PV systems. The second comparison demonstrates that the integration of storage systems reduces annual energy bills by 20.2% and CO2 emissions by 23%, while reducing the IM costs of the PV systems by 63.4%. However, these benefits are accompanied by a 32.2% increase in total costs due to the integration of energy storage systems.