Leaf-Resolved Light Modelling in Agrivoltaic Greenhouse Scenes

Abstract

Agrivoltaic greenhouses combine crop production with photovoltaic electricity generation. The integration of PV modules, however, changes the amount and spatial distribution of light available to the crop canopy. Assessing this effect within a complex three dimensional crop canopy requires a modelling approach that represents both the agrivoltaic greenhouse geometry and light interception at the individual leaf level. The reviewed modelling approaches either represent an agrivoltaic greenhouse without a geometrically resolved crop canopy or include a leaf-resolved canopy but lack a PV system. To address this gap, an existing Radiance-based agrivoltaic ray tracing framework was extended with
functionality for constructing parameterised tomato plant and greenhouse geometries together with component-specific wavelength-dependent material properties. These developments were applied to reconstruct an agrivoltaic greenhouse demonstrator from the SYMBIOSYST project in Ath, Belgium, as a digital twin. Spectral ray tracing simulations over the photosynthetically active radiation range were then used to assess light absorption at leaflet, plant and canopy level.

Canopy light absorption was compared across the 0%, 33%, and 50% PV roof coverage regions of the demonstrator. Relative to the nominal 0% PV region, seasonal absorbed photosynthetically active radiation (APAR) was approximately 26% lower under 33% roof coverage and 34% lower under 50% roof coverage. Crop-row position and cross shading also influenced these differences, with neighbouring PV sections reducing seasonal APAR in the nominal 0% region by approximately 5.6%. Beyond these seasonal differences, the leaf-resolved analysis showed how light absorption varied within the canopy. The vertical APAR profiles showed that light absorption per unit leaf area increased with canopy height, with the influence of PV roof coverage becoming more pronounced towards the upper canopy. Radiation conditions also affected this distribution, with predominantly direct radiation producing stronger spatial and temporal variation in canopy APAR than predominantly diffuse radiation. Overall, the results show that canopy light absorption and distribution are shaped by the interaction between PV configuration, greenhouse geometry, radiation conditions, and canopy structure rather than by PV roof coverage alone. Although the quantitative results are specific to the SYMBIOSYST demonstrator, the extended framework can be used to construct and simulate other agrivoltaic greenhouse systems with different greenhouse geometries, PV layouts, and tomato canopy configurations.