What is a Solar Water Pump & How Does it Work

Solar Water Pumps are devices made to pump water using the energy of the sun. For rural locations that are not part of the local electricity grid, Solar pumps offer a clean and simple alternative to fuel-burning generators and windmills. They require no fuel deliveries and very little maintenance.

Typical uses for solar pumps include:

  • Fountain pumps
  • Pool pumps
  • Transfer pumps
  • Circulation pumps in ponds
  • Providing water for livestock
  • Irrigation pumps
  • Home pumps

As you may know there are, different kinds of solar powered water pumps, depending on purpose. Here we explain the different types of pumps as well as the components included in a solar water pumping system.

whatIsASolarWaterPump

What is a Solar Water Pump?

More correctly a solar water pumping system consisting of three main components:

  • A solar module (panel(s)) which provide the power
  • A controller which controls the system
  • A pump unit which is actually a pump coupled to a motor.

A solar module can be mounted almost anywhere, but it should face in a northerly direction (in Australia). If you are planning to use solar pumping on a farm the modules and pump controller should be mounted on a raised pole and fenced off, in order to help keep them out of range of animals. Animals can cause significant damage to the system if any of its components are mounted too low and in a place accessible to the animals.

The control box regulates the functions of the pump and responds to inputs from sensors such as low water level or tank full.

Lastly the “pump” which is actually a pump directly coupled to a motor. Depending on type, these units can be placed above ground or submerged in a bore creek or dam.

Solar pumps come in two major types:

  • Helical rotor pumps, also called screw or progressive cavity pumps. The helical rotor rotates inside a rubber tube called the Stator. There is a small cavity between these two parts which moves from one end of the pump to the other. With each rotation a small amount of water is forced through the pump. These pumps are best suited to applications requiring low to medium flows at high heads.
  • Centrifugal Pumps contain a rotating impeller. Water enters the centre of the impellor and is thrown outwards. Some pumps may have more than one impellor arranged so that the output of one section feeds the next section. These are called multistage pumps and are capable of achieving higher pressures that a single impellor pump. Centrifugal pumps sre generally used where high flows are required at low heads.

The next distinction is where the pump is located. It can be surface mounted i.e on or above ground or submerged e.g. in a bore or dam or river.

  • Surface pumps are limited by the distance they can lift water to the pump. 8m is about the maximum suction lift. Uses include pressure, delivery, and booster pumps. Delivery pumps move water from one location to another. Some pumps handle high water pressures but most are intended for moving moderate volumes of water at low pressures. An example of this type of pumping would be on a farm where water needs to be moved from a cistern or dam to water tanks on the farm. Another typical application’ of a delivery pump is supplying water to an RV or camping trailer.
  • Submersible pumps are primarily used for pumping from bores but can also be used for pumping from rivers or dams. Bore pumps fit inside the bore casing in a drilled hole. Some older bores drilled for windmills were fitted with a 4″ cast iron casing and only 3″solar submersible pumps will fit. Most modern bores are fitted with 150mm or larger PVC casings.

It is important to remember that the deeper the water, or the greater the lift, the more expensive the pumping system will be. Most solar pumps currently available are 250W to 1500W (1/3 to 2 HP). At Sunstream we stock solar pumping systems which will pump to heads of over 100m while others can deliver 20,000 L/hr at 8m head.

howASolarPumpWorks

How Does Solar Water Pumping Work?

A solar-powered water pumping system is composed of a power source consisting of one or more PV (photovoltaic) panels. Solar cells are the building blocks for solar panels. Each solar cell has two or more specially prepared layers of semiconducting material (generally silicon) that produce direct current (DC) electricity when exposed to sunlight.

This current then flows to a control box which manages the power generated. Using a program called Maximum Power Point Tracking the control box can regulate the speed of the pump motor so it runs at best efficiency. It also protects the pump motor from over voltage or low power situations. It can also start and stop the pump based on input from sensors and at the same time displaying the systems status.

Whenever the sun shines the current turns the motor and the pump operates. If there is a requirement to run the pump for longer hours eg at night then a battery system must be included. This can store electricity during the day to run the pump later but it does require more solar panels to charge the battery.
In early systems the motor was driven by DC current through brushes (brushes needed to be replaced periodically). Today’s modern systems use high efficiency brushless motors which are driven by an alternating current produced by the control box.

Installation

A solar-powered pumping system is fairly easy install, especially if you decide that you do not need a battery-coupled solar water pump. In this case the system will only work when the sun is shining and stop when it doesn’t.

A mounting pole is concreted into the ground and once the concrete has set the solar panels are mounted on it as is the control box.

Sunstream’s pumps are supplied pre-wired with power cable and all you have to do is connect the poly pipe and safety cable to the pump, position the low water sensor, and cable tie the cables to the pipe.

Plug the leads from the solar panels into the control box. After a visual check of the connections lower the pump into the bore, dam etc. Switch on and wait for the water to flow.