Civil Engineering Reference
In-Depth Information
FIGURE 8-19
Actuator motor of the suntracker. (Source: American Sun Company, Blue Hill, Maine. With
permission.)
FIGURE 8-20
Sun tracking actuator principle. The two differentially connected sensors at 45° generate signal
proportional to the pointing error.
When the sun is obscured by a dark cloud, the tracker may aim at the next
brightest object, which is generally the edge of the cloud. When the cloud
is gone, the tracker aims at the sun once again. Such sun-hunting is elimi-
nated in newer suntracker design.
One method of designing the suntracker is to use two pv cells mounted
on two 45° wedges (
Figure 8-20
)
, and connecting them differentially in series
through an actuator motor. When the sun is perfectly normal, the current
on both cells are equal to I
· cos 45°. Since they are connected in series
opposition, the net current in the motor is zero, and the array stays put. On
o
