AC Motor or DC Motor for Solar Water Pumping
Which type of motor AC or DC is best for solar water pumping system?
There are several different types of solar-powered pumps depending on how they have been classified. But primarily there are four types of solar water pumps–submersible pumps and surface pumps, direct current (DC) pumps and alternate current (AC) pumps.
As the name suggests, a submersible pump is located deep below the ground level and remains submerged under water. The suction head of the submersible pump is beyond a depth of 10 metres. The installation of these pumps is done by digging a borewell, which leads to an increase in its installation and maintenance cost.
The surface pumps remains out of water and in the open. They are installed where the water table is within a depth of 10 metres. As they need to be on the surface, these pumps are easier to install and maintain. They are, however, not apt for deep water table.
This pump runs on a motor which operates on direct current, therefore no battery or inverter is needed in this type of pump.
The motor of this pump operates on alternating current, which means the direct current produced by the solar panels gets converted to AC using the inverter. The conversion from DC to AC leads to loss of power from generation and consumption.
The selection is based on the groundwater level and the water source. In the case of a borewell with a water table deeper than 10-15 metres, a submersible pump is used. If it is an open well, pond, etc, then using a surface pump is better. Also, the surface pump is installed when the water level is less than 10 metres.
Based on the classification, the following types of motor pump sets are available:
- Surface mounted motor pump set
- Submersible motor pump set
- Floating motor pump set
- Any other type of motor pump set after approval from test centres of the Ministry of New and Renewable Energy.
- Although DC pumps have an advantage over AC pumps in terms of higher efficiency and no requirement of an inverter for operation, the cost of DC pumps is higher. Also, the repair and maintenance of DC pumps are difficult in rural and remote areas due to lack of service centres in these areas.