Types of Solar Trackers

Several kind of solar tracking systems are proposed in the literature; one can classify them according to the degree of freedom and control strategy. The schematic below illustrates types of solar trackers.

solar tracker

Degrees of freedom (DoF) and/or control strategy: Control Strategy
?Fixed devices – Domestic and small-scale commercial photovoltaic and hot-water panels are usually fixed, often flush-mounted on a roof top. Passive controlled trackers – have no electronic sensors or actuators
Single-axis trackers – Single-axis solar trackers rotate on one axis moving back and forth in a single direction. Open-loop controlled trackers

  • Have no sensors too but use microprocessor and are based on mathematical formulae to predict the sun’s position.
  • Dependent on geographical location and the start time situation of the system.
Dual-axis trackers – Dual-axis tracker, along with the function of a single axis tracker follows the sun vertically and horizontally and helps obtain maximum solar energy generation. Closed-loop controlled trackers.

  • Use the information of electro-optic sensors for estimating the location of the sun.
  • Not dependent on geographical location and the start time situation of the system.

Open and closed loop trackers together can be called as Active tracker.

Concentrated photovoltaic (CPV) trackers

  • The tracking functionality in CPV modules is used to orient the optics such that the incoming light is focused to a photovoltaic collector.
  • CPV modules that concentrate in one dimension must be tracked normal to the sun in one axis. CPV modules that concentrate in two dimensions must be tracked normal to the sun in two axes.