Optimizing Energy Yield and Economic Benefit of Renewable Energy Technologies for Urban Mediterranean Dwellings

Mediterranean European cities are characterized by high population density and limited space for large-scale implementation of renewable energy installations. This paper addresses the optimization of renewable energy installations in Mediterranean dwellings with the scope of increasing their energy contribution and cost-effectiveness. In a case study for Malta, the three technologies studied were solar photovoltaics, solar water heating, and heat pump water heating. Technical and economic analyses were performed on a number of reference configurations using Polysun software (version 2022.8). Sensitivity analyses were also conducted to study the impact that different technical and economic factors have on the performance of the configurations considered. Finally, comparisons were made between the techno-economic results obtained from the reference and sensitivity analyses. Based on data collected, the presence of renewable energy source (RES) technologies in the residential sector of Malta was characterized and correlated with the types of dwellings considered. Among the results obtained, it was found that although a solar RES installation may experience some shading, this does not mean that it is rendered economically unfeasible. Moreover, from the simulations conducted, electrical energy storage technology was considered as too premature unless strongly subsidized, making economic sense only in specific circumstances. On the other hand, although heat pump water heating technology is also relatively modern, it was concluded to be the most beneficial in terms of both energy yield and economic benefit, generally speaking. Furthermore, it was determined that in a higher occupancy dwelling, solar water heating (SWH) and heat pump water heating (HPWH) result in considerably more attractive energy savings.