Previous Year Question
With reference to solar water pumps, consider the following statements.
Solar power can be used for running surface pumps and not for submersible pumps.
Solar power can be used for running centrifugal pumps and not the ones with piston.
Which of the statements given above is/are correct?
Only 1
Only 2
Both 1 and 2
Neither 1 nor 2
Correct Answer: D
Detailed Solution
In a solar water-pumping system, solar photovoltaic panels convert sunlight into electrical energy.
This electrical energy operates the water pump through a controller and motor.
Solar energy can operate both surface and submersible pumps.
A surface pump is installed outside the water source and generally draws water from shallow sources.
A submersible pump is installed within the water and can extract water from borewells and deep wells.
Solar submersible pumps may be of both AC and DC types. Therefore, Statement 1 is not correct.
Centrifugal pumps can be operated using solar energy.
Centrifugal pumps are generally suitable for requirements involving high flow rates and comparatively low or moderate pressure.
Solar energy can also operate piston pumps or other positive-displacement pumps.
Piston pumps may be useful for applications requiring higher pressure or greater lift at a lower flow rate.
Therefore, Statement 2, which restricts solar energy only to centrifugal pumps, is also not correct.
A suitable pump is selected according to the depth of the water source, required water flow, total head, available solar radiation and nature of use.
Solar pumps may operate directly during daylight or be connected to batteries and water-storage arrangements where required.
Storing water in an elevated tank instead of using electrical batteries can be a simpler and less expensive option in many irrigation systems.
Solar pumps can reduce diesel consumption and operating costs, but uncontrolled use may create a risk of excessive groundwater extraction.