Sultan Tekie, Sebastian Zainali, Tekai Eddine Khalil Zidane, Silvia Ma Lu , Mohammed Guezgouz, Jie Zhang, Stefano Amaducci, Pietro Elia Campana

Extensive research has explored the impact of shading on vegetation growth and crop yield under agrivoltaic (APV) systems. These studies have revealed a notable connection between shading and crop yields, with certain crop varieties showing benefits from shadings e.g., Berries and Leafy Vegetables, Forage remaining largely unaffected, and some crops e.g., Cereals, Grain Legumes, Fruits, and Root crops experiencing reduced yields when subjected to shaded conditions. Previous studies often overlooked environmental factors such as temperature, evapotranspiration, and precipitation when assessing shading effects on crop yield, making it difficult to fully understand their impact on crop performance. This study seeks to address this research gap by integrating a drought index, known as the Standardized Precipitation Evapotranspiration Index (SPEI), into existing improved meta-analysis on shade and crop yield across various crops. The SPEI implicitly includes information concerning temperature, potential evapotranspiration, and precipitation, and it is easily retrievable globally and at a reasonable temporal resolution. Multiple linear regression (MLR) techniques are used to analyse different crop categories. The MLRresults with and without incorporating SPEI are compared to assess the shading influence on determining crop yield amidst varying environmental conditions. Including SPEI resulted in improved performance metrics across all crop categories. For example, the least improvement was observed in Fruit with a 17.1% increase in R², while the most significant improvement was seen in Maize with a 62.8% increase in R². Moreover, the analysis revealed that in over half of the crop categories, the SPEI statistics exhibited greater significance compared to the shading level parameter. Consequently, this study concludes that considering environmental factors implicitly included in SPEI alongside the shading level offers a more comprehensive understanding of crop yield dynamics under APV systems.