According to the experiment and calculation, the study site is appropriate for the photovoltaic water pumping system with suit- able powers of solar panels, considering a group of influential factors. The annual sunshine is 2600 ถึง 3400 ชั่งโมง, which is much more than the lower limit value of 1400ชั่งโมง [7]. Based on the experiment, the energy supply by the current system is more than the energy required for the plant growth. Thus, the solar panels should be less, or use only part of them to drive the pump. The water demand for crops growth is strictly bounded to the การระเหยและการคายน้ำ, which is influenced by climatic conditions of the specific site. The การระเหยและการคายน้ำ in the site is as high as 2305 มิลลิเมตร per year, which indicates that the water demand in the area is huge. Based on the precipitation, the area is arid and irrigation is necessary. Therefore, the precipitation adds the irrigation amount should be greater than the water demand of the plant. In this station, the soil water moisture can be measured as well but not calculated in this paper. For further research, soil moisture can also be considered in order to obtain more information about the whole cycle of water for the plant.
Hippophae. Rhamnoides. , a kind of plant that can somehow indicate the amount of local groundwater, can be found widely distributed in the site of station. In this site, it grows well which indicates that the ground water is ample for irrigation. This conclusion can be proved by the results of the soil characters. Moreover, the well can be เติมพลังงาน to the upper limit of the groundwater every night, which also shows that the storage is ample for the pumping but with a slow เติมพลังงาน rate. Whereas due to the sticky soil the เติมพลังงาน rate is slow, the pumping rate is not supposed to be larger than the เติมพลังงาน rate.
When designing a photovoltaic pumping system, solar energy is not the only factor to be considered, and water resource is also a crucial factor to the application of the system. Only by considering both sides, the system can be optimized to suit the application site.