Sizing of large-scale photovoltaic irrigation systems. Model for environmental and economic optimisation of grid-hybrid systems

• NSGA-II is used for optimal PV sizing balancing cost and environmental impact. • Selling surplus energy increases viable solutions and system performance. • The model adapts to various locations and energy demand profiles. • Combines optimization and LCA for sustainable PV design in agriculture. • The tool supports decision-making offering multiple optimal options. This paper presents a model for the optimal sizing of large grid-connected hybrid photovoltaic systems for irrigation. The model integrates economic and environmental criteria through two objective functions: Life Cycle Cost (LCC) and Life Cycle Assessment (LCA). These functions depend on key variables, such as PV panel type, installation configuration (fixed or solar tracker), and installed peak power. To solve this multi-objective problem, a modified version of the Non-dominated Sorting Genetic Algorithm II (NSGA-II) was used. The methodology was applied to a real case study in an Irrigation District in southern Spain, which already has a hybrid PV system, which allowed the model’s results to be compared with the currently adopted solution. The results showed that the algorithm can identify optimal solutions that balance the LCC and LCA, offering efficient configurations for both scenarios in which surplus PV energy can be sold and those in which it is not possible. In the scenario without surplus sale the solution space exhibited more restricted variability across both objectives but feasible configurations that reduced both objective functions were identified. Compared to a real installation, the model was able to find solutions that improved the LCC by 7.53% and the LCA by 5.67%.