Integrated approaches to renewable energy: assessing the economic feasibility of PV, BESS, and DSM in Mediterranean public buildings

Policy incentives for self-consumption of solar energy are driving widespread adoption of photovoltaic (PV) systems, battery energy storage (BESS), and demand-side management (DSM) in public buildings, yet guidance on optimal sizing and integration of these technologies remains limited. This study analyzes operational data from six Mediterranean public buildings to quantify how PV capacity, BESS, and DSM jointly affect energy performance and economic returns. Results show that the PV-to-load ratio and seasonal solar availability determine the attainable level of self-sufficiency, with summer values approximately 10-30 percentage points higher than in winter across sites. The temporal alignment between PV generation and electricity demand, enhanced through load shifting, governs how closely buildings approach this limit. Battery storage provides the greatest gains when sized to cover late-afternoon and evening demand; beyond this range, additional capacity yields diminishing benefits unless combined with increased winter PV generation or demand flexibility. Shifting flexible loads toward midday consistently improves the utilization of on-site PV generation and reduces the storage capacity required to achieve similar performance. From an economic perspective, configurations that prioritize the use of midday PV surplus to offset evening grid imports yield the highest net present value (NPV) under self-consumption tariffs, while net-billing schemes allow greater PV oversizing. Optimal configurations, PV sized for winter yield, storage for evening-shoulder coverage, and DSM shifting 25-50% of flexible loads, raise self-sufficiency by 10-30% and maximize NPV across tariff regimes.