Towards SDG 7: A Quantitative Sustainability Framework for Evaluating PV+BES Systems in the Low-Carbon Transition

Sustainability in the energy sector requires a pragmatic and interdisciplinary approach. This study analyses the economic profitability and environmental effectiveness of photovoltaic (PV) systems integrated with battery energy storage (BES) systems through a quantitative framework based on Net Present Value analysis, sensitivity analysis, Least Absolute Shrinkage and Selection Operator regression and greenhouse gas emission reduction value, using a shopping mall in Rome as a case study. By applying uniform percentage changes to economic and environmental variables, the study identifies the critical factors that influence profitability in different self-consumption scenarios. The results show that, in PV systems, the avoided cost in the electricity bill (energy purchase price) is the most significant lever, especially in contexts with high self-consumption, while the sale price becomes more important when self-consumption is low. In BES systems, increased self-consumption remains the main factor improving profitability, although investment costs continue to have a significant impact. Tax deductions have less impact, especially in mature markets. From an environmental point of view, the reduction in emissions depends heavily on the composition of the fossil fuel mix replaced, with a limited additional environmental impact from BES. The results offer operational guidance for prosumers, energy managers and investors to achieve SDG 7 by optimising self-consumption rate, electricity purchase price, PV+BES investment cost, and the fossil-fuel mix replaced to improve the economic and environmental performance of PV+BES systems.