Solar powered pumps are very popular for small scale drinking water supply systems. Historically, diesel generating sets were widely used to provide electrical power for pumping stations and in rural areas. However, these diesel engines required a lot of maintenance work (changing filters, filling fuel tanks, changing oil). Solar-powered pumps, on the other hand, require minimal maintenance and some types of pumps can operate for up to five years without any upkeep or supervision. This type of solution is perfect for applications located a long way from the main grid and in environments where maintenance and supervision of a diesel generation system are difficult.
If the initial investment in a solar powered pumping station is compared with that of a diesel powered station and the maintenance costs linked to both solutions are taken over a six to 10-year period, it can be shown that the solar-powered solutions are less costly for systems pumping approximately 2,000 m 3 per day (equivalent to 40 m 3 /day at 50 m or 20 m 3 /day at 100 m).
How it works
The WATERSUN range systems are assemblies that combine solar power and hydraulics to supply water in a community setting. There are 13 pumps of different sizes in the WATERSUN range: thre displacement pumps and 10 centrifugal pumps. Depending on the depth and the required output, the pump can either be connected to a DC motor or an AC motor. There are two families within the WATERSUN range: SQFlex (DC motor) and SP (AC motor).
WATERSUN SQFlex: Specifications and capacity
- Maximum daily output (Q) : 100 m 3 /day
- Total Dynamic Head (TDH) : between 2 m and 100 m
- Solar field power (P) : between 200 Wp and 900 Wp
- Motor type : Direct current
- Pump type : Displacement or centrifugal
WATERSUN SP: Specifications and capacity
- Maximum daily output (Q) : 200 m 3 /day
- Total Dynamic Head (TDH) : between 2 m and 200 m
- Solar field power (P) : between 400 Wp and 1,800 Wp
- Motor type : Alternating current
- Pump type : Centrifugal
Advantages
- The pumping and motor technology is exactly the same as for traditional systems connected to the grid and is thus well known and widely available.
- The assembly is freestanding and silent and the method of pumping according to the sunshine is well suited to the demand pattern.
- The output is relatively large for moderate depths (10 to 100 m).
- The systems are reliable and require very little maintenance.
- Start-up torque is relatively low.
Maintenance
- Pump stages require cleaning every five years (depending on water quality).
- Solar panels must be cleaned regularly.
Community solar-powered pumping station architecture
The solar panels generate electrical power as a direct current, which is converted via a static transducer to supply a submerged motor pump set. The motor pump set is made up of an electronically switched three-phase alternating or direct current motor coupled with a multiple-stage centrifugal pump or a displacement pump, depending on the required output. The centrifugal pump works by turning the motor's kinetic energy into a rotating movement on wheels with vanes acting on the fluid; a displacement pump uses a spiral screw movement to literally "push" the water to the surface. The systems offer either PW850 75 Wp or PW1650 165 Wp modules mounted on a tilting bracket which optimises photovoltaic power generation according to site latitude. A fixed transducer is also supplied; this will be surface-mounted and is used to convert the direct current generated by the solar field into alternating or direct current to supply the pump motor. All pumping systems are delivered in full with the rising main, power cable and submersible pump as well as all installation and wiring accessories necessary, they come uninstalled with an installation instruction manual.
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 WATERSUN – TYPICAL CONFIGURATION (non-contractual illustration) |
Typical applications
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 Typical applications shown above include solar field and water tank, solar-powered water pumping and irrigation. |