Photosynthetic photon flux density distribution inside photovoltaic greenhouses, numerical simulation, and experimental results

A methodology for estimating the photosynthetic photon flux density (PPFD) distribution inside a photovoltaic greenhouse using a combination of a commercial lighting simulation software and available meteorological data was investigated in this study. Numerical results were compared with those measured inside an experimental greenhouse partially covered with photovoltaic panels. The PPFD distribution inside the greenhouse was calculated on the basis of outside measurements of PPFD at the site of the experimental greenhouse and data acquired at a nearby meteorological station. Daily average percent differences were in all cases lower than 19.0%. Assuming that such differences are acceptable for agronomic purposes, on a monthly basis the numerical model demonstrated a good capability to predict the shading effect inside the photovoltaic greenhouse. Hourly analysis showed higher fluctuation of measured versus calculated data, meaning that the model was able to predict the qualitative behavior of the distribution and its average value but underestimated the fluctuation of values.