Design Principles of PV Irrigation Systems
3.1.2 completed solar tracker system
A completed solar tracker system is a specific device. It is for moving the PV to follow sunshine, so maximize the irradiation received. A solar tracking system is composed of three parts: mechanism, driving motors, tracking controller.
The mechanism is the driving part of the tracking system. This part must be withstand harsh weather, also it must also have an long life same as PV.
For the type of mechanism, solar tracking systems include one-axis trackers or two-axis trackers.
184.108.40.206.1 One-Axis Tracker
If solar tracker is complex, it is expensive, so single-axis tracking systems are the best solution. A single-axis solar tracker with linear actuators moves the panel on an approximate facing the Sun’s position. The rotation axis can be horizontal, vertical, or oblique. The scheme of a one-axis tracker showing both the rotation axis and the collector plane . The angle between these two units usually keeps constant in this type of tracker.
220.127.116.11.2 Two-Axis Trackers
Using two-axis trackers can get more energy collection, because its totally free of movement. The tracker can face the sun’s rays throughout the day.
18.104.22.168 Driving Motor
For the driving mechanism, solar trackers have active or passive solar trackers. Active driving mechanism has electric motors (DC or AC) or hydraulic systems.
The driving mechanism usually uses linear actuators because it allows a simple and precise control for moving. DC ones are more popular now. For one-axis trackers, only one motor need, but for two-axis trackers, two motors need.
22.214.171.124 Solar Tracker Control
Somehow,solar tracker belongs to solar tracking systems. It initialize the PV panels base on previously sun trails. Solar trackers use a solar radiation sensor to control to run the system.
126.96.36.199.1 Feedback Controllers
These controllers use solar sensors to detect the position of the Sun. For this purpose, the sensors set up photosensitive elements on the panel. Both at dawn or under cloudy days, the tracker sensors may lose functions, but it will use auto-control tracking system in memory. It controls the rotation of the motors until getting signal again.
188.8.131.52.2 Open-Loop Controllers
This control technique also uses a microprocessor, so it does not need any sensor to detect the Sun. The movement of the Sun using astronomic relationships date. Write some program into the microprocessor, so that the microprocessor itself can calculate the Sun’s position at any time. This control needn’t think of cloudy or other low radiation weather .