Simulation of grape culture irrigation with photovoltaic V-trough pumping systems

In large areas of the Northeast of Brazil, the population is faced with the severe problem of water shortage aggravated with the lack of electric power. However, some places, like the area next to the river São Francisco, near the city of Petrolina, in the state of Pernambuco, have become quite prosperous with the cultivation of grape crops, either for wine production or to be consumed as fruits. Wine exports have grown as an important economic activity in the region. On the other hand, in areas far from the electric network, photovoltaic pumping systems have contributed to the supply of water for local rural communities. Production of fruits, with water supplied by photovoltaic systems, might, then, become a good alternative in terms of local economic activities. The viability of this proposal depends strongly on the market value of the crop. Taking advantage of some significant technical benefits provided by low concentration tracking devices we propose to use those systems to drive local irrigated crops. Among the large family of concentrators available, V-troughs are particularly adequate for photovoltaic applications since, for certain combinations of the concentration ratio (C) and vertex angle (Ψ), they provide a perfectly uniform illumination in the region where the modules are located (absorber region). A drip irrigation system, located in the city of Petrolina, has been simulated and the maximum surface that can be irrigated by a V-trough photovoltaic pumping equipment was estimated by performing a water balance on a monthly basis. With an array of 1.3 kWp it was found that the system is able to irrigate, without deficit, 2.11 ha. A fixed photovoltaic pumping equipment, with the same photovoltaic array, is able to irrigate an area of 1.20 ha. In both cases, the water stored in the soil contributes with an increase of 33% to the irrigated area, as compared to the case where that contribution is not considered.