Solar Water Pumping Systems
Solar water pumping system is based on a common electrical pump with the difference that electricity is supplied by the PV panels. Solar pumps mainly use DC-based motors so they can leverage the power from solar panels without using inverters. Besides, DC-based motors are less susceptible to voltage fluctuations. Pumping the water through solar power as opposed to grid-tied pumping is highly relevant in remote areas with limited grid availability. Solar pumps move the same volume of water slower than the traditional motors do so they are suitable for moving the water over long distances in an extended time range.
The 3 constituent parts of the system are:
- PV panel
- A pump
- A pump controller
The pump controller has 2 important roles. First, it matches the output power of the PV panel with the pump's input power. Depending on weather conditions the power generated by the PV panel can vary so a controller is needed to stabilize the power output. Second, it provides low and high voltage protection to avoid a damage to the pump's motor. Again, due to the variability of the sun's intensity, a controller needs to be there to maintain a consistent output voltage.
Depending on the manufacturer the controller may have additional features like
- Remote performance monitoring through a web or mobile interface
- Pump shut off function when the water tank is full
- Water pressure regulation
- Automatic shut off when head pressure is too big
- Alternating power source between solar and other means (diesel, gas)
Head pressure is the difference in the levels between where the water is and where it needs to be.
By their motor's voltage type pumps can be Direct Current (DC) based or Alternating Current (AC) based. DC motors are more efficient than their AC counterparts so a system with DC motor will require a smaller surface PV panel. In case of an AC pump, the controller also acts as an inverter for converting DC into AC.
By their application area, water pumps have 2 main types: surface and submersible. The choice between these 2 types depends on the system's purpose. For getting water from the wells or boreholes submersible pumps are used. In alternative applications where the head pressure is not high a surface pump is used.
The advantages of solar water pumps over traditional diesel or gas water pumps are manifold.
The solar water systems
- have no fuel costs,
- are easy to install,
- have a low maintenance cost,
- are portable and environmentally friendly
On the downside, as with everything solar, they have
- higher initial cost
- strong dependence on sunny hours.
Solar Well Pumps
Solar well pumps are the most common type of submersible solar pumps. They are submerged into wells to pump the water out. Depending on the PV panel's surface and well's depth the volume of the pumped water will vary. These pump systems are usually equipped with all the necessary components for right away operation after installation. Submersible solar water pumps can be used for seasonal draining of the swimming pools, irrigation, water for livestock and more.
Solar Fountain Pump
A solar fountain is a small solar water pumping system used for decorative purposes. The PV panel can be integrated with other components or it can be wired from a distance. There may be various configurations of solar fountains:
- outside solar fountain like in a garden setting
- inside a building with panels mounted outside
Both inside and outside fountains can be either battery-backed or not. Battery-backed systems can work at night and during the cloudy hours but it raises the overall cost.