Energy sustainable greenhouse crop cultivation using photovoltaic technologies

The sustainability of energy and food supplies has come to represent a major concern throughout the world today. Greenhouse cultivation, an intensive food-production system, contributes fresh vegetables and fruits to the world food supply. Greenhouse crop yields and quality can be improved by microclimate controls powered by fuels and grid electricity inputs. Therefore, producing abundant and quality crops with improved energy efficiency has been pursued as a challenge to be addressed by researchers and practitioners. Although application of photovoltaics (PV) to greenhouses can reduce fuel and grid electricity consumption, PV inherently conflicts with cultivation because both photosynthesis and PV depend on sunlight availability. Various contrivances have been explored to enhance the compatibility of cultivation and PV power generation. This review describes important aspects of greenhouse cultivation, electricity demand in greenhouses, state-of-the-art of greenhouse PV systems, and PV shading effects on plants. Finally, prospects for energy-sustainable greenhouse PV technologies are presented.