Solar Trackers are devices that come in conjunction with the mounting structures and help direct the panels in the direction the sun moves.
As the solar industry progresses, developers are increasingly becoming aware of the enhanced CUFs that tracker implementation can bring about. But being a nascent market, there is a lot of uncertainty in selecting the best trackers for a solar power plant, especially with regard to cost savings and generation output per MW they could bring about.
There are basically two kinds of trackers:
Single Axis Trackers
A single axis system is most commonly used for most standard PV Power Plant. Single axis solar trackers rotate in one direction moving back and forth. These types of trackers usually have simple levers which can be used to tilt the panels depending on the season so that it can harness the maximum energy from the Sun. They can increase the performance of the power plant by 20%.Single-axis trackers make sense in the Southern states due to their proximity to the equator and usually costs about an additional 40 Lacs/MW with respect to the capital costs.
Dual Axis Trackers
Dual axis systems – as indicative of the same – move in two directions, on both the horizontal and the vertical axis making complete use of the sun’s rays for the entire day. With a Dual Axis Tracking system more energy can be generated from a given land area, as compared to Fixed tilt installation or Single Axis. In northern parts of India like Punjab, Rajasthan etc., which are located at a higher latitude, these could be beneficial. They can produce an increase in performance of up to 35%.
Will the usage of trackers come with an excess in the maintenance services required for the power plant?
One aspect that many developers are concerned about, when it comes to use of trackers is the extra maintenance required. Many of them have asked us at Solar Mango whether the trackers could impose significant maintenance costs, and whether trackers could break down often, leading to disruption of plant output. We can say that these fears are unjustified, as long as you procure the tracker solution from a reputed company. Yes, trackers have moving parts and hence require regular maintenance, mainly regular inspection and lubrication. However, the tracker movements are slow and gradual, and not subject to the same wear and tear that a fast running motor would, for instance. In summary, trackers supplied by reputed companies, from an Indian or an international company, will be able to provide you with a significantly higher output at the cost of only a marginal increase in maintenance efforts and costs.
The motion in trackers can be either mechanical or hydraulic based. The hydraulic trackers are piston-cylinder based. It effectively uses a motor that moves a working fluid from a fluid reservoir into a cylinder through an open valve. The fluid builds up in the cylinder and pushes the piston which can cause the desired change in the alignment of panels.
While the hydraulic trackers use a piston-cylinder arrangement to cause the orientation-change in panels, the mechanical trackers are based on motor and gear based motions.
How do you ensure the trackers employed in your plant is a safe bet?
Most people are still sceptical about the tracker technology, it being a relatively new technology. However, Solar Mango, after intense research and interaction with industry personnel, has listed below indicators with which you can evaluate your trackers.
Over and above the indicators provided below (which you can cross-verify with the datasheets provided by the manufacturer), you might also want to do a background check on the past performance of the company chosen.
- Range of motion
This indicates the maximum range within which the track can align the system according to change in position of the sun The wider the range, the better it is in terms of expected generation increase. Most good quality trackers have a range around 45 ᵒ to East and 45 ᵒ to West.
- Module Compatibility
Make sure the tracker technology has previously been found compatible with the panels, or at least panels of similar physical dimensions, used for the power plants.
- Back-tracking Feature
This is to optimise sunlight captivity during early morning and late afternoons- to reduce the impact of shading from other panels. Evaluate your tracker favourably if it has this feature.
- Power Consumption for Operation
Most good quality trackers employed today use less than 0.05% of the energy generated by the plant per MW for its operation.
- Protection Rating for Motors
Trackers with a high protection rating against dust and water, ideally having an IP Rating greater than 65 are found to be of good quality.
Make sure this feature is present in your trackers. This provides for aligning the panels optimally during high wind speeds. Also make sure that the time taken for auto-stowing is about 15 minutes.
- Land Required Per MW
A tracker of good design should be commanding less than 6.5 acres per MW for installation.
- Maximum Wind Speed Tolerance
Ensure that there are no reported cases of damage to the structures due to poor tolerance against high wind loads. Ensure that your trackers are designed to tolerate wind speeds in the range of 150 kmph.
- Tonnage Used
For a strong and resilient structures ensure that the tracker technology is designed for about 60-70 tonnes of steel per MW.
- Warranty Terms
You might want to evaluate the warranty terms and conditions provided by the manufacturers. Most commonly the warranty period of the trackers come at about 10 years for the mechanical components in the system and 5 years for the control and actuators.
You might want to check out these questions on Solar Power Plant Evaluation- Components:
- How well have the components been chosen?- Here
- Presence of local service support from component manufacturers?- Here
- What have been the degradation rates in panels?- Here
- How good are the inverters?- Here
- What types of monitoring solutions are employed by the power plant?- Here
- Are the components suppliers in business?- Here
- What are the warranty clauses attached to key components?-Here
- Can you retrofit additional components to an existing power plant to increase generation? – Here