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306 CHAPTER 9 Design Principles of Photovoltaic Irrigation Systems

Several types of one-axis tracking can be distinguished. These types (Figures
9.8e9.11) are shown in Table 9.2.
3.1.2.1.2 Two-Axis Trackers Using two-axis trackers, maximum energy collection
can be achieved because, due to its total freedom of movement (northesouth and
eastewest), the tracker can face the sun’s rays throughout the day (Fig. 9.12).

Table 9.2 Types of One-Axis Tracking

NortheSouth horizontal axis tracking
The axis is horizontal and its direction is NortheSouth and
c ¼ 90 degrees.

Figure 9.8

Polar tracking: NortheSouth polar axis tilted on an angle
equal to the latitude of the site
The rotation is adjusted in such a way that the tracker follows
the meridian of the earth containing the sun. The angular
velocity is 15 degrees/h. With this configuration, the solar
tracker can be used both in northern latitudes and in places
near the equator.
Figure 9.9

EasteWest horizontal axis tracking
In this configuration, the rotation axis is placed parallel to the
ground and in an eastewest direction. In this way, the
panels can rotate only to follow the Sun at its altitude angle,
correcting the position of the panels every day due to the
Sun’s declination. This configuration is not commonly used
because the energy collected is much lower than that
obtained with other configurations. Figure 9.10

Azimuthal axis tracking
The tilting angle of the surface is constant and equal to the
latitude of the site. The simple and robust mechanics of the
azimuthal trackers can trade off the smaller collection of
radiation with respect to the two axes trackers, making them
the most widely used in practice.

Figure 9.11