Analysis of the impact of photovoltaic module layout density on the light-yhermal environment and sweet potato growth in agrivoltaic systems

Photovoltaic Agriculture Systems (PAS) have emerged as an innovative land-use pattern to balance the synergistic "electricity generation aboveground, and crop cultivation belowground", particularly against the rapidly growing global demand for the renewable energy and intensifying pressure on agricultural land resources. The sSolar photovoltaic power generation can be spatially converged with the conventional agricultural production, theoretically enhancing the comprehensive output per unit land area. Significant promise can be intertwined with the global challenges of energy security, agricultural sustainability, and carbon neutrality. However, the dual-use framework can also introduce the complex ecological compromises. Crucially, the photovoltaic panel deployment on agricultural land can inevitably reshape the sub-panel microenvironments. The solar radiation intensity and its spectral redistribution can reach the crop canopy after modifications. Subsequently, the dynamic soil temperature fluctuations can induce after alterations. The photothermal regimes can directly mediate the critical crop physio-ecological processes, including photosynthesis, respiration, nutrient dynamics, water-use efficiency, as well as ultimately govern the yield formation and quality accumulation. Consequently, the photovoltaic panel deployment density—an important parameter to determine the spatial light heterogeneity—can be precisely regulated on the crop microenvironmental dynamics. A pivotal challenge can remainremains to successfully optimize the PAS configurations for the synergistic maximization of the "power generation-yield-quality" multi-objectives. It is often required for the PAS transitioning to transition from the localized pilot demonstrations toward scalable, sustainable implementation. In the present study, a strategically selected PAS demonstration base was employed in Lishui District, Nanjing, China. The knowledge gap was also proposed to concern the photovoltaic arrays’ impacts on the crop microenvironments. A coverage density gradient experiment was then carried out to capitalize on its standardized single-span photovoltaic support structure (6.8 m). Three treatments were set—50%, 75%, and 100% coverage—alongside an open-field control. The microenvironmental heterogeneity was systematically characterized under spatially discontinuous PV arrays. Two discrete micro-zones were defined within each structural span: the inter-panel zone (receiving greater incident radiation) and the under-panel zone (northern shaded area), in the entire growth cycle of sweet potato. The intensive monitoring was precisely tracked on the solar radiation intensity—including Photosynthetically Active Radiation (PAR)—and soil temperature variations across all zones and controls. An environmental profile was generated after monitoring. Key findings demonstrated that there were the significant effects of the deployment density on microenvironments and crop outcomes. The photovoltaic coverage density was reduced the gradient in the radiation intensity, and then moderated soil temperature profiles. Critically, the full coverage (100%) was significantly reduced the tuber yield and tuber number per plant, highlighting the productivity limitations under maximal shading. Conversely, the semi-coverage (50%) was exerted the comparatively minor yield impacts, indicating a pragmatic threshold for the agricultural viability. Nutritional quality exhibited the compensatory adjustments: the higher coverage densities increased the starch and protein content, while there was the a decrease in the soluble sugar content. Moderate shading shared the beneficial influence on the specific quality indices. The context-responsive photovoltaic layout standards were then established to quantitatively map the response relationships between coverage density and crop performance. The framework was investigated to optimize the PAS implementations. The synergistic land-use innovation can also offer the clean energy production with the agricultural sustainability and nutritional output.