Solar water pump Layout Design

Structure

Solar panels can be ground-mounted, roof-mounted, or post-mounted depending on the site conditions. Metallic structures are normally used to hold the panels, these structures are designed to withstand high winds and stormy weather.

The structure itself needs to be properly coated and protected against environmental factors such as rain, humidity, and other conditions.


Orientation

In order to maximize the performance of solar panels, it is essential to install them facing true south, with an acceptable tolerance of 15 degrees towards east or west that doesn’t significantly affect the performance. For applications needing solar energy in the morning more than it does in the afternoon, a shift towards the east is practical to receive the solar rays as early as possible.

In some situations there could be some shade caused by trees or other obstacles at one of the sides, which requires shifting the panels slighting to the opposite sides to avoid shading as much as possible.


Tilt

The panel can get the best out of the solar radiation when its surface receives the solar rays at a perpendicular angle, allowing for a maximum solar ray density per unit area. But since the sun path varies from day to another, being at higher levels during the summer and lower in relation to the horizon.

According to the sun path and the latitude of Lebanon, the best tilt angle has been shown to be around 55 degrees in winter and 15 degrees in summer, with 35 being an average value.

Rule of thumb says that the tilt angle needs to be almost as much as the latitude of the location with a 5 degrees tolerance.

The optimal solution would be changing the tilt angle on daily basis to match the solar radiation angle, but since this is not a practical solution, the application decides on the tilt angle. In applications demanding maximum production in winter for example, there is a tendency to go above average to guarantee best performance in higher demand seasons.

For solar water pumping, water demand is at its highest during summer season, thus solar

panels are best when tilted at an angle of 30 or 25 degrees relative to horizontal ground level.




Sun Tracking

Although not very practical for solar water pumping applications, it is worth mentioning that some applications do require sun tracking. This is done either by daily tracking, or seasonal tracking, and sometimes both together known as dual tracking as shown in Figure 3 earlier.

Tracking systems can increase the output by as much as 35%, but also incur additional costs and require more maintenance over the lifetime of the system.


Pump Location

The pump should be located in an enclosed room called a pump pit or a pump house. Surface pumps are not water proof and need to be kept away from water and protected from environmental conditions to prolong their lifetime and reduce maintenance requirements. If a submersible pump is used, the pump will be inserted in the borehole, but should not be too close to the bottom of the borehole or else it will stuck in dirt and lead to pump damage.

Distance between the pump and the PV panels should be kept to a minimum to reduce voltage drop in the cables. Increased distance causes harmonics and would require a harmonics filter to avoid damages to the pump and the inverter/controller.



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