Optimal design of a standalone direct pumping photovoltaic system for deficit irrigation of olive orchards

Abstract

Abstract In this work, an optimal standalone direct pumping photovoltaic irrigation system is proposed for the deficit irrigation of olive orchards. A simulation model of the system was developed in order to obtain the economically optimal design of this system. This model is composed of different sub-models: the photovoltaic power generation capacity sub-model, the direct pumping management sub-model and the sub-model that evaluates the economic and productive response of the crop to the application of water. The model simulates for increasing values of peak power of the photovoltaic system, the water and energy balance in the photovoltaic irrigation system and the crop yield. It also calculates the investments and operational costs of the system and, finally, the net economic returns to the farmer. The model enables us to select the optimal design of the system that achieves its maximum economic profitability. The economically optimal designs provided by the model are not achieved for a completely full irrigation of the crop but rather for deficit irrigation. In this way, we propose a new approach to PV irrigation systems design and management that we call PV opportunity irrigation (PVOI). PVOI makes use of the ability of many crops to undergo some water stress without experiencing a significant yield loss in order to reduce the size of the PV irrigation system. The operational strategy in the PVOI approach is to irrigate as long as enough power is supplied by the PV array. Unlike any other conventional design method available in literature, the total amount of water applied to the crop depends on the energy provided by the PV array rather than on a strict fulfillment of the pre-established crop water irrigation requirements. The application of the PVOI approach implies not only a reduction in the investment costs of the system but also some water savings, which is very important in areas with water scarcity.