Solar trackers are of two types, single and dual axis trackers. Single axis trackers track in a singular way i.e. follows the Sun’s East-West or North-South movement, while Dual axis tracking has two degrees of freedom. This means that they have both a horizontal and a vertical axis i.e. both the east/west axis and the north/south axis and thus they can track the sun’s entire motion in the sky. These trackers hence have the potential to maximize the total power output by orienting the panels in direct sunlight for the maximum number of hours in a day.
A dual axis solar panel generates up to 40% more electricity than a static type, but costs 100% more and has larger maintenance costs. The amount of energy spent externally to orient the solar panel must be deducted from the total amount of energy produced in order to accurately gauge the energy produced by the panels.
How the dual axis tracker works
There are three means of changing a solar tracker’s position:
- Manual – Some personnel are deployed who adjust the position of the solar tracker at various times during the day. This tracking method is economically viable in developing countries where the price of labor is low.
- Passive – The solar tracker is fitted with a bulb of liquid when exposed to sun gets heated up. This causes the liquid to evaporate. This volume expansion pushes and tilts the attached solar tracker towards the sun.
- Active –Electric motors or hydraulic cylinders are used to adjust the position of the tracker.
Advantages and Disadvantages
There are some advantages and disadvantages of dual tracking, which is why even if they can be used at all latitudes but still they have not found widespread commercial application. Advantages of dual axis trackers include:
- Can give 40% more electricity than a non moving solar panel
- Higher degree of flexibility, allowing for a higher energy output on sunny days
- Higher degree of accuracy in directional pointing
Disadvantages of dual axis trackers include:
- Lots of moving parts makes it more likely for components to fail
- Lower lifespan and lower reliability
- Unreliable performance in cloudy or overcast weather
- Very costly .Can generate 40% more electricity compared to static panels but is also 100% more costly.