The pump in the traditional water pumping system is generally powered by a stable power grid. Because the voltage amplitude and frequency of the power supply grid are fixed, the running speed of the pump in the system is stable and unchanged, and it has been working at the highest speed (50Hz) set by the system, to ensure that the water output of the water lifting system is constant, means the water output at each moment of the system is consistent and at the maximum value.

 

Nowadays, in various irrigation fields, it is very common to use solar pumping system to carry out daily water pumping and irrigation. The water pump in the solar water pumping system is powered by the solar panel of the system. The reality is that there is a corresponding relationship between the power generation of solar panels and the intensity of sunlight. The stronger the sunlight, the greater the power generation of the panels, and the water output of the system will change with the change of the light intensity. Therefore, the water output of the system may change every moment. When the light intensity reaches the maximum, the water output of the system also reaches the maximum.

 

It can be seen that in the solar water pumping system, the pump speed must be adjusted in real time according to the intensity of sunlight to ensure the stable and reliable operation of the system. Therefore, the variable frequency speed regulation control of the water pump according to the light intensity is the biggest difference between the solar water pumping system and the traditional water pumping system. When the sunlight is strong, the battery panel generates a large amount of electricity, and the pump runs at 50Hz, and the water output reaches the maximum, which is the same as the power supply from the power grid; But when the light becomes weak, the running frequency of the water pump will be less than 50Hz, and the water output will be reduced accordingly. When the current solar water pumping system is applied, it needs to be designed according to the user's daily water demand, which cannot be accurate to every minute.

 

Case description:
 

Take a solar water pumping system project of Shenzhen Solartech with a daily water consumption of 65m3 and a head of 11 meters as an example:

1. The intensity of the sun changes with time

2. System running time: 8am – 4pm (8 hours), sunrise water volume: 65m3
 

 

Graph of solar light intensity over time

 

System running time: 8am – 4pm (8 hours), sunrise water volume: 65m3