Modeling, Design and Construction of a Zero-Energy PV Greenhouse for Applications in Mediterranean Climates

This paper concerns the design, modelling, and construction of a high-efficiency mini PV greenhouse performing as a Nearly Zero Energy Building (NZEB). The greenhouse is equipped with a semi-transparent roof-mounted photovoltaic system (3 kWhp) that feeds an air-source heat pump providing cooling and heating. The PV-generated power can be also stored in a battery. A dynamic simulation model (EPlus) of the real greenhouse is developed to predict its performance and investigate beneficial control strategies. The hourly profiles of different variables (energy, temperatures, illuminance) are deeply investigated. The energy-saving strategies, as reflective shading and controlled natural ventilation, prove to reduce the yearly energy needs by 30%. The energy storage model is developed by the Authors and coupled with hourly solar production. The PV electric model includes the temperature effect on module performance, the inverter efficiency curve, and the battery state of charge. The coupled dynamic analysis shows that the photovoltaic plant meets the air conditioning requirements for 94% of the hours of operation and that the energy surplus could feed the grid with approximately 1355 kWhel per year. The validation of the present model will be possible with future measurements and monitoring of the greenhouse once operating in place.