Multi-objective optimization for sizing of residential hybrid renewable systems with battery storage: Balancing economic, environmental, and energy autonomy perspectives

The expansion of residential prosumer systems has increased the need for sustainable sizing models that incorporate local generation and storage. This study proposes a multi-objective model for the optimal sizing of residential hybrid renewable energy systems, evaluated from economic, environmental, and energy autonomy perspectives. The approach combines Response Surface Methodology and Normal Boundary Intersection to model and optimize three objective functions: Net Present Value, equivalent CO 2 emissions, and Self-sufficiency. A post-Pareto selection method is used to identify an optimal solution from each Pareto front. A case study is developed across the nine capitals of the Brazilian Northeast region, considering the current regulatory changes to the net-metering system established by Law 14,300/2022. This study advances the literature by explicitly integrating economic, environmental (accounting for life-cycle emissions of renewable technologies), and energy self-sufficiency objectives in the optimal sizing of residential photovoltaic/wind/battery systems under a real regulatory transition. The main results indicate that, despite the regulatory change, investments remain viable, particularly when based on photovoltaic energy. The selected solutions achieved self-sufficiency levels of 54.7% to 68.1% and life-cycle emissions of 6894 to 8655 kg CO2eq . The results also indicate the benefit of small-scale wind energy over increasing battery bank capacity, as it enables greater self-sufficiency with a lower environmental impact. Despite this, the use of wind energy remains limited to regions with favorable wind regimes; however, these areas still represent a considerable portion of a country with continental dimensions such as Brazil. Formulating public policies and incentives tailored to each region's specificities can ensure greater integration of distributed generation without negatively affecting energy distributors or consumers who do not use this technology, thereby providing a more sustainable model in the long term.