Tracking The Sun! All You Wanted To Know About Solar Trackers

What is a Solar Tracker

A Solar Tracker is a mechanical device which follows the movement of the sun as it rotates from the east to the west every day. Solar Trackers are used to keep solar panels oriented directly towards the sun, as it moves through the sky. The angle of rotation is very important as the relative position of sun changes daily from east to west. The angle of rotation varies from -60 degrees to +60 degrees (East-West direction), but for tropical countries like India, a single axis movement of -45 degrees to +45 degrees is enough for extracting the maximum gain. These days solar trackers are becoming increasingly important and major solar panel manufacturers like First Solar and Trina Solar are selling solar trackers as well. Solar trackers were mostly used in the U.S. market, but given its economic benefits, developers in India and China have also increasingly started using these trackers for their projects.

Components of a Solar Tracker 

a) Tracker Mount – is the skeletal structure holding the panel in proper inclined position

b) Driver – used to control the rotation of the motor shaft based on the load

c) Sensors – detect relevant parameters induced by the sun and yields output

d) Motor – controls the movement of the tracker

e) Algorithm – used to calculate sun’s position from algorithms using the time, date and geographical location.

Also, read Impact of GST on Renewable Energy Sector in India

History and Development of Solar Trackers

During the early 2000s, there was much debate about whether tracker technology or fixed-tilt option was better for utilities. Developers were skeptical of shifting to a new technology largely on concerns of maintenance. However, tracker technology continued to develop as a viable alternative to fixed-tilt for utility-scale solar plants.

Various tracker components like motors, controllers, and sensors became smaller and smaller. The tracking systems were also optimized to reduce component requirements. Gears became smaller and efficient; sensors became more compact, using SCADA and monitoring technology. The whole setup became getting sleeker, simpler to install without the requirement of many specialized tools.

Solar trackers have continually evolved to become better and more efficient. From single axis to dual axis trackers, and from passive to active trackers, trackers today are equipped with smart features that guarantee better output. In India itself, solar trackers have features like weather proof mechanism, multimode intelligent operations, link tube with articulated joints, dust avoidance and rain mode. Some recent innovations also include simplified designs that have fewer motor parts and self-calibration. Through back tracking feature, solar trackers can also keep inter-row shading under check. These trackers are also capable of self-cleaning of the modules and hence do not require any routine maintenance.

Array Technologies CEO Ron Corio said. “The best possible outcome for solar is that you install a system and you don’t have to do much with it — it just produces power for 30 years.”

Types of Solar Tracker

There are two different drivers that dictate the motion of the trackers: passive and active.

I) Passive trackers – Depend entirely on the sun’s heat for the movement of the tracker using a hydraulic mechanism. A low boiling point compressed gas fluid is used that drives to one side or the other causing the tracker to move in response to an imbalance. They do not consume any power.

II) Active trackers – Uses a controller to monitor the sun’s movement in order to direct motors that move the trackers. Electrical circuits in the form of photo sensors are used. Active trackers thus use power.

Active trackers are more precise than passive trackers, hence more widely used where accuracy is required, for instance when concentrating solar collectors are used. Passive trackers are more widely used in normal solar PV applications.

The two basic categories of trackers are single axis and dual axis.

1. Single Axis Tracker:

These trackers have one degree of freedom that acts as an axis of rotation and they can have either a horizontal or vertical axis. The axis of rotation of single axis tracker is typically aligned along a true North meridian. They can be aligned in any cardinal direction with advanced tracking algorithms.

There are several implementations of single axis trackers:

i) Horizontal single axis tracker (HSAT)

ii) Horizontal single axis tracker with tilted modules (HTSAT)

iii) Vertical single axis tracker (VSAT)

iv) Tilted single axis trackers (TSAT)

v) Polar aligned single axis trackers (PSAT)

2. Dual Axis Tracker:

These trackers have two degrees of freedom that act as axes of rotation and these axes are typically normal to one another. These trackers have both horizontal and vertical axis and can move along the sun’s apparent motion.

The common implementations of dual axis trackers are:

i) Tip-tilt dual axis tracker (TTDAT)

ii) Azimuth-altitude dual axis tracker (AADAT)

Dual axis trackers are more complex, require additional land, more O&M and lower reliability as compared to single axis trackers, although power generation efficiency is higher.

Where Can Solar Trackers be used

Solar Trackers are mostly used in ground mounted solar farms of capacity more than 1 MW. It is difficult to use solar trackers on residential rooftop installations. The combination of energy improvement, lower product cost and lower installation complexity results in compelling economics in larger deployments. Solar Trackers are almost universally used in case of solar thermal technology because they make use of optics to generate high amounts of heat.

Advantages of Solar Tracker

The main reason to use a solar tracker is to produce more power by reducing the cost of energy. Using Solar Trackers increases the amount of solar energy which is received by the solar energy collector (solar panels) and improves the energy output. Solar Trackers can increase the output of solar panels by 15%-40%, which improves the overall economics of the solar panel project. A tracking system produces more power during peak demand hours compared to fixed mounted systems.

Trackers make immense economic sense and typically there is a payback of fewer than 3.5 years on tracker investment and an overall increase in the IRR of the project. They also lead to the lowest levelized cost of electricity (LCOE) in solar projects. The increase in output easily compensates for the higher costs associated with solar trackers. Solar Trackers are very effective in places where solar insolation and efficiency of solar panels being used is high.

India Solar Tracker Market

The costs have come down drastically over the years due to an improvement in technology and growing competition. It is estimated that almost 50% of the overall tracker market will be using trackers by 2022 which means almost 35-50 GW of solar trackers will be required annually by 2022. The overall market for solar trackers should grow to around $5-7 billion then, up from just $1 billion now.

Improvement in price has been mainly due to better technology and bigger scale. Steel has become the biggest cost component accounting for 70% of the cost of trackers. Steel prices should remain subdued given the huge structural overcapacity globally. China’s huge amount of idle capacity will keep steel prices capped and solar tracker costs in check. Just like Chinese solar panels, Chinese Solar Trackers are also much cheaper than that available locally. However, the operational history for most pure play Chinese tracker companies is not too long.

India’s solar market is 5GW of which only 20% is currently catered by trackers. This means the country still has a huge potential. Today India has 1GW of solar power plants equipped with trackers compared to none two years ago. India is expected to add about 3-4GW of single axis tracker installations per year as a result of its ambitious solar target of installing 100GW of solar by 2022. It is expected that more than 50% of the plants being installed after 2016 will use trackers in India. Compare this to the global markets, where 85% of the solar systems already use trackers.

Major Players in The Indian Solar Tracker Market

Most of the tracker manufacturers have been bought by the large U.S. solar developers like First Solar and SunPower, who have been integrating tracker options into their product offerings.

Solar trackers in India have seen a number of players entering the market. Some of the notable ones include Mahindra, Vikram and Waaree Solar. These firms are also large solar panel makers or EPC/developers which mean that they will use in-house products for their installations. Global players such as First Solar and NexTracker are also present in India and have supplied hundreds of megawatts of products to different solar projects across the country.

Major Indian solar tracker players are Mahindra and start-ups like Scorpius Trackers and SmartTrak Solar.

1. Scorpius Tracker is a Pune based startup backed by three angel investors who have an in-depth knowledge in the renewable energy sector. The company was incorporated in 2012 and grew revenues from INR 2.5 crore in 2014-15 to INR 17 crore in 2015-16. The company has installed over 300 trackers and structure designs for solar pumping, roof top, and other distributed system applications. This three-year-old company has signed MoUs worth 1,250MW and has firm orders for 500MW. Scorpius Tracker manufactures single axis trackers between 100 kW to 500 kW. A single tracker block is generally 500 kW. WiFi enabled inter-tracker controller and Wind station communication system are also available.

2.SmartTrak Solar manufactures both single and dual axis trackers, enhancing energy level by 25-35% and also provides direct and easy access to monitoring and control. SmartTrak also provides tracker control system which allows online monitoring and control and configuration of the tracking system at client’s convenience.

3. Mahindra is one of the largest EPC players in India. The company through its portfolio company Mahindra Susten manufactures MSAT100, an indigenously designed single axis tracker which is significantly gaining traction in the Indian market at affordable prices. The company has so far supplied over 500 trackers and installed more than 10MW trackers in Tamil Nadu, Andhra Pradesh, and Telangana. About 24% increase in the generation has been observed at installed sites.

4. Vikram Solar is a prominent solar panel manufacturer in India. The company also has a presence in the EPC market and recently entered the solar tracker market in a big way. The company launched HELITRAC which is an advanced solar tracker with intelligent operations and weather proof mechanism. The product is also easy to install.

5. Relyon Solar is India’s leading solar company established in 2010 and headquartered in Pune. The company manufactures single axis trackers which are proved to deliver average 20% more sunshine every day. The company claims its trackers to be the most flexible tracking solution with large tilt angle and stowage mode for the wind. They are more accurate with smart algorithm tracking. These trackers are maintenance free and have a cleaning mode for routine cleaning.

6. Ganges Internationale Pvt Ltd. is a major module mounting structure provider in India. Last year the company announced the launch of solar trackers in India in collaboration with American solar solutions provider SunLink Corporation. The tracking system will be an innovative world-class tested product in single axis tracking technology that is expected to increase energy generation by 15-20%.

7. NexTracker is the world’s largest solar tracker company and also has a large presence in India. The company has been taken over by one of the largest electrical and electronic OEMs Flextronics. NEXTracker designs and manufactures one of the world’s most advanced single-axis photovoltaic trackers that orient PV panels to maximize energy output. Other foreign tracker companies having a huge presence in India are Sun Track; and Power Way, Arch Tech and Patriot Solar of China.

While Array Technologies and NexTracker are still the biggest firms in this market globally, other players have started to enter making the field much more competitive. The top 5 international companies making solar trackers are Array Technologies, SunPower, First Solar, Nextracker and Soitec.

Price of Solar Trackers – India

Mounting structures typically account for 7% of the overall capital cost of solar PV power projects, as per the Central Electricity Regulatory Commission. The selection of tracker type is dependent on many factors including installation size, electric rates, government incentives, land constraints, latitude and local weather. Cost plays a major role in deciding the solar components, especially in India.

Trackers typically add upfront costs of 5%-10% on large utility-scale projects. The cost for solar trackers is ~INR 25-40 lakhs/ MW for single axis trackers in India. Dual axis trackers are more expensive than single axis trackers.

The tracking system should be designed in a way to be able to withstand years of harsh weather conditions. Single axis trackers have evolved a lot to what they are today but there is still room for improvement. For example, most of these trackers are installed with a limit switch which does not function in case of bad weather conditions and is also prone to improper installation and operating errors. At many locations, these switches are now replaced with mechanical hard-stops which overcome all these limitations and thus improve efficiency. But there are still small hurdles to a successful tracker installation. Challenges exist in the form of bad weather or windy conditions, maintenance, cleaning and the overall efficient operation of the whole system. Innovations so far have been fruitful and have addressed the concerns, but with a booming solar market in India, it will be interesting to see how the tracker market evolves over the next one or two decades.

Conclusion

Single-axis trackers are more beneficial compared to double axis trackers in the Indian scenario. India has set up an ambitious target of installing 100 GW of solar power by 2022. Both the market size and the market share of trackers is poised to increase at a rapid pace in India. Trackers will more than makeup for their modest increase in upfront costs over the lifetime of the project. In the past developers were of the belief that trackers will significantly add up to maintenance costs which were a big challenge for installing trackers. However, that perception is quickly changing with mass adoption and increased the overall efficiency of projects when using solar trackers.

India has 100% rural electrification plan which will increase the country’s overall demand for energy. Utility-scale solar is here to stay in India for long and continued improvement in performance and cost of all major components including modules, trackers and inverters is going to make it a competitive source of electricity going forward.

Note: The article is written by me and was originally published in a leading renewable energy magazine in India, SmartEnergy.