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Nowadays the world, especially the developing countries, is experiencing a rapid growth in demand for energy in order to improve the standard of living. Nevertheless, fossil energy sources are no more considered adequate source of energy. Among renewable energies, solar radiation is one of the most potential alternatives. The exploitation of solar energy is a cost competitive solution compared to the traditional electricity production systems, especially in arid remote areas, where electric grid connection is impossible and the dependence on an imported fuel supply that is difficult and risky. The majority of the world’s developing countries, where the water demand is increasing, due to the growth of population, is found within the tropics and hence have ample sources of solar insolation. One of the most common uses of solar energy is for standalone Photovoltaic Water Pumping Systems (PVWPS), producing electric energy to supply water both for drinking and irrigation purposes, excellent for small to medium scale pumping and moderate agricultural needs.

These systems, added to a careful assessment of local water resources, can also be very useful to solve one of the most outstanding problems in remote areas in China: the desertification of grassland, which is causing economic and environmental difficulties.

SIDA research (Swedish International Development Cooperation Agency) fits with this scope, through the specific project “Demonstration and Scale-Up of Photovoltaic Solar Water Pumping for the Conservation of Grassland and Farmland in China”. This project is to integrate renewable Photovoltaic (PV) technology, water-saving irrigation techniques and water resource management to design a robust and user-friendly system to bring benefits to farmers. The results will provide a technically robust and economically viable system and a business model for commercial scale-up in real applications.

This work of thesis takes part in SIDA project, and it is focused on the creation of a general model to design an irrigation system with micro or sprinkler irrigation technology starting from the evaluation of the water demand. This system has to be suitable for the values ​​of water demand required in terms of surface coverage irrigated and waste of water. The purpose is to create a kind of model useful to design the irrigation system according to the peculiar local conditions.

The model is applied to real locations (uplands in north of China) for different size of the irrigated area: 0.5 ha and 1 ha with both micro and sprinkler irrigation, 5 ha and 6 ha only with sprinkler irrigation. The model provides the values of the start head which the pump has to lift to ensure the best performance of the systems.

The model has been validated with the commercial software IrriPro V. 2.5 which showed a good reliability of the model and of the results obtained.

The evaluation of the whole systems costs carried out in order to evaluate the best options shows how for the extensive cultures the sprinkler irrigation is the best solution.