Introduction
A dual axis solar panel is a type of solar tracker. Solar trackers are used to track the sun as it moves through the sky. Solar trackers can be split into several categories based upon the type of actuation and axis of rotation. A typical dual axis solar panel can generate up to 40% more electricity than a static type, but costs perhaps 100% more and has larger maintenance costs.
The amount of power required to move the solar panel must be deducted from the total amount of power gained in order to accurately record the total power gain.
Actuator Types
There are three main means of changing a solar tracker’s position:
- Manual – personnel adjust the position of the solar tracker at various times during the day. This method is only economically viable in developing countries where the price of labor is low.
- Passive – the solar tracker is fitted with a bulb of liquid that has a low boiling point. When the sun’s rays shine on the bulb, the liquid evaporates causing an imbalance which tilts the solar tracker towards the sun.
- Active – the solar tracker uses electric motors or hydraulic cylinders to adjust the position of the tracker.
Axis of Rotation
There are three main types of solar tracker based upon the axis of rotation:
- Horizontal - the tracker has one degree of freedom and rotates on the North-South axis. This type of tracker is used for low to medium latitudes and most large commercial applications.
- Vertical – the tracker has one degree of freedom and rotates on the East-West axis. This type of tracker is used for high latitudes, but rarely for large commercial applications.
- Dual Axis – the tracker has two degrees of freedom and rotates on the East-West and North-South axis. This type of tracker can be used for all latitudes, but is not used for large commercial applications.
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How Dual Axis Solar Panels Work
The below video is an extract from our Mechanical and Electrical Engineering Explained Online Video Course.
The panel locates the position of the sun by using a solar sensor, or, by receiving a signal via the global positioning system (GPS). Once the position of the sun is known, the position of the panel is changed to point directly at the sun. Dual axis solar panels are actively controlled using electric motors or hydraulic rams.
As the sun moves, so too does the solar panel. As the relative position of the sun to the solar panel changes only slowly, it is not necessary to constantly move the solar panel.
An anemometer (wind sensor) is used to calculate the wind speed and stow the panel in the event of high wind speeds.
Note
Another example of a dual axis controlled payload is the heliostat. You can see how heliostats are used in our solar furnace example.
Additional Resources
https://www.solarpowerworldonline.com/2013/04/how-does-a-solar-tracker-work/
https://en.wikipedia.org/wiki/Solar_tracker
http://www.solartracker.guide/working-principle-of-a-solar-tracker/