Development of a Simple Tool for Estimating Irradiation Reduction in Agrivoltaic Greenhouses

Agrivoltaic greenhouses combine photovoltaic (PV) energy production with horticultural cultivation, but their success depends on maintaining sufficient light transmission to crops. Current modelling tools provide accurate projections of PV performance yet are often too complex for early-stage design or regulatory assessments. This work presents PASSIFLORA, a simplified but physically consistent framework for estimating both crop-level irradiation and PV energy yield in greenhouses. The model reuses and adapts geometric ray-casting and hemispherical sampling algorithms originally developed in PASE, enabling efficient calculation of direct and diffuse irradiance beneath PV-covered roofs. A graphical interface allows users to configure greenhouse geometry, roof layouts and cover properties, with automatic module placement and an option to sweep module coverage to achieve a target irradiation reduction factor. Validation against PVsyst was carried out for a Gothic tunnel greenhouse in the region of Toledo (Spain). The results showed excellent agreement in crop-level irradiation (<0.5% difference) and close agreement in PV yield (within 3%). Case studies further demonstrated the application of the tool to assess different factors such as tunnel configuration, layout patterns, and greenhouse orientation. PASSIFLORA provides a fast, transparent and regulation-oriented approach for pre-design of agrivoltaic greenhouses, complementing detailed engineering software in later project stages.