An overview of design and management of photovoltaic greenhouses: current weaknesses and solutions for the future

The photovoltaic greenhouse (PVG) is an effective example of green energy application to agriculture: it can potentially contribute to improve the environmental sustainability of the greenhouse farms, by producing both electricity and crops on the same area, without consuming further land for conventional agriculture. The research and development of this sector is seeking for solutions to improve the compatibility of these agrosystems with respect to the crops environmental limiting factors. At present, it is possible to use simulation models to predict the solar radiation available inside several PVG types, according to the percentage of the greenhouse area covered with PV panels, and assess the related agronomic sustainability. This information is crucial for farmers and greenhouse manufacturers, because it allows the identification of the optimal design criteria of PVGs and suitable crops, aiming to increase the horticultural productivity of future installations. The design parameters of PVGs and the related management will be assessed, highlighting the weaknesses of the current structures and suggesting the optimal design criteria for the next PVG generations. Several aspects are discussed by reviewing the current literature on the topic, such as the use of single or multi- span structures, PV panels density and installation patterns of the PV panels on the roof, greenhouse height and orientation, openings design, cladding materials and innovative semi- transparent PV technologies. The general basic practices for managing the PVG and the crops in terms of fertigation and tillage are also discussed. The proper management of these aspects can optimize the greenhouse solar radiation for the canopy and increase the agronomic productivity and profitability of PVGs.