Generally when people think of agriculture they will picture a tractor or some other machinery.
The humble water pump, however, uses as much if not more energy and is just as essential to production.
Pumps are mostly used to move water from the water source, which could be a dam, river or bore, through pipes to a point of usage or a storage facility, e.g. a water tank or an irrigation system.
Here in Australia, the cost of grid connection or a lack of access to grid supplied electricity means that many farmers use diesel pumps.
Electric pumps, however, are a superior option for several reasons, they are lower maintenance, to set up for automated and remote control, and have the ability to use solar power either as the main power source or as a supplementary power source for grid connected pumps.
No matter the power source, the principles of pump selection and operation are the same. Cost-efficient operation relies on selecting the right size and design of pump and maintaining it correctly.
Choosing a pump
There is a wide range of pumps available, and it can be confusing trying to make a choice. The first step in making a choice is to calculate the pumping requirements of the intended application. You will need to know what your daily water usage needs will be as well as gathering information about the water source, discharge point and the distance between the two.
If it won’t be supported by other power sources, like the electricity grid or battery storage, the pump must be able to move enough water to match your operation’s daily water requirements. The pump must also have enough power to move the required amount of water from the water source
How a pump works
A pump is a system that is used to move liquid. Pumps move liquid by utilising energy to build the amount of pressure in the system.
The flow rate is the amount of water pumped through during a certain time period. The flow rates are usually quoted in L/min or m./day (where 1m. = 1,000L). When using a solar pumping system, the expected flow rates of the pump are calculated from the variability of the site’s solar radiation levels:
- If you have a minimum daily flow rate each day, no matter the daylight hours, your systems design would need to increase the required daily flow rate to compensate for reduced pumping performance on less sunny/overcast days.
- The hourly flow rate must consider the limited number of sun hours per day to pump the water. The estimated flow rate also needs to allow that the levels of solar radiation vary from hour to hour.