Solar light distribution inside a greenhouse with the roof area entirely covered with photovoltaic panels

Most photovoltaic (PV) greenhouses in Europe have maximised the energy production without considering the requirements of the crops, by applying PV panels on most part of the roof area. The aim of this work is to calculate the solar light distribution in a photovoltaic (PV) greenhouse where the entire roof area is covered with PV panels (100% cover ratio). The calculation of the incident global was estimated with clear sky conditions on several observation points located inside the greenhouse at 1.5 m from the ground level. The validation of the simulated data was conducted through measurements inside a PV greenhouse complex located in Florinas, Italy (40°38'38"N; 8°39'31"E), composed by 24 single-span greenhouse modules of 837 m2 each and total area of 2.2 ha. The roof area of each module was completely covered with a monocrystalline PV array with slope of 20° and a rated power of 22 kWp. The results were shown through a map of light distribution on the greenhouse area, which highlighted the most penalised zones and the percentage of available global radiation, compared to the same greenhouse without PV array. Good agreement was shown by the simulated data, compared to measurements (mean R2=0.78). The global radiation on the greenhouse area was 33% on yearly basis, compared to the potential value with no PV panels on the roof. The zones close to the gable walls and the south side wall suffered less shading compared to the central portion of the greenhouse area. The map of cumulated light distribution can support the growers to increase the agronomic sustainability of the PV greenhouse, since it will allow in perspective the identification of species and crop management practices for a profitable cultivation.