Light simulation and yield assessment of lettuce cultivated under agrivoltaic systems in Northern Thailand

This study aimed to (i) simulate and validate light intensity under the Agrivoltaic system (AVS) and (ii) evaluate the feasibility of lettuce (Lactuca sativa L.; varieties: 'Butter Head', 'Green Oak' and 'Red Oak') plantation under AVS. . Two planting systems located in Northern Thailand were compared: (i) "Greenhouse (GH)" = lettuce planting inside the greenhouse conditions (control plot), and (ii) "Agrivoltaic system (AVS)" = lettuce planting underneath a 10 kW photovoltaic installation. Sunlight estimation was performed using Rhinoceros 3D software with Grasshopper Plugin and Ladybug Tools, and the model accuracy was validated. For the experimental study, lettuce growth (plant height and canopy width) and yields (fresh and dry weight) were collected every 7 days after transplanting. The fresh weight (FW) was directly measured after harvest. The samples were oven-dried at 65 °C and the dry weight (DW) was recorded. The results showed high accuracy of the model to predict sunlight under specific conditions with R² of 0.82. Plant height and canopy width under the AVS were not significantly different from those in the GH system. Significant higher FW and DW were observed for the GH system (FW = 61.6 g plant^-1 and DW = 2.9 g plant^-1) as compared to those in the AVS (FW = 42.2 g plant^-1 and DW = 2.2 g plant^-1). These results demonstrate that the Rhinoceros 3D software has the potential to predict sunlight and that sunlight under AVS is adequate for growing crops.