Design and Development of a Photovoltaic Power System for Tropical Greenhouse Cooling

Renewable energy sources like photovoltaic (PV) panels are used today in many applications. Natural ventilation in tropical greenhouse is common method for ventilation, which gives higher inside temperatures compared to the outside temperatures. In addition, this type of ventilation is not enough to reduce high temperature inside the structure in low land areas. Thus the requirement of cooling is increased. Use of the fossil fuel to run the cooling fans are not economically viable due to increasing of fuel cost and greenhouses are not always located near the electrical grid. This research presents a study on the installation and test of a complete photovoltaic hybrid system for cooling a tropical greenhouse. A hybrid photovoltaic system consisting of two photovoltaic sub-systems were connected to each other. This system includes 48 photovoltaic solar Panels with 18.75 watt each, one inverter, 1 charge controller and a battery bank (including 12 batteries). The PV system is located at University Putra Malaysia (UPM) Research Park. The national electricity grid was used as a backup unit. The load consisted of two misting fans for cooling greenhouse (during test period time) with 400 Watt electric power and five hours (11:00 am to 16:00 pm) daily operation. The results obtained showed that the maximum current drawn from the array was found to be 14.9 ampere at 13:00 pm (with load). The voltage of array was found to be 26.9 volt while the voltage and current of battery bank were found to be 26.2 volt and 23.0 ampere respectively. In conclusion, this study highlights the primary study of PV hybrid energy systems for tropical greenhouse cooling as an application of renewable energy in Selangor, Malaysia. The results showed that PV system would be suitable to supply electricity to cover the loads requirement demands without using energy from the grid.