Terrain-following solar tracking with a pneumatic screw



Sunfolding’s new TopoTrack rows are said to be 10 times shorter than traditional trackers and can offer 20 degrees of variation between trackers, improving slope tolerance between rows.

What sets Sunfolding’s terrain-following tracking devices apart from other models is pneumatics, a 360-year-old technology that converts power into movement.

Traditional trackers are mechanically more complex, which can make installation and maintenance expensive. Sunfolding developers found that pneumatics offered a simpler approach and advantages in certain solar structures. Some of these benefits include a tank (or bladder) to store air so they can continue to operate due to power loss.

They can also operate due to air loss and can operate continuously without the threat of overheating. Read more about solar and pneumatics in Sunfolding’s white paper. Without batteries or metallic drive components, the pneumatic technology can also withstand very low temperatures where traditional tracking devices have had problems.

As Chip McDaniel noted in Industrial Equipment News, the advantage of pneumatics is simplicity, low cost and reliability. It provides a “fast path to traffic” and offers significant power in a small space.

The patented AirDrive technology used by Sunfolding was invented by Leila Madrone, the company’s founder and CTO. Madrone is a robotics major with both a bachelor’s and master’s degree in electrical engineering and computer science from MIT, with a concentration in robotics and mechatronics. Early in his career, he worked on the automation of the genomics industry and the commercialization of NASA’s robotics equipment. Founded in 2012, Sunfolding was spun off from MIT’s Otherlab. In 2016, the company won a $4.2 million ARPA award for its “pneumatically actuated PV tracking system.”

AirDrive system

At the heart of its tracking system is AirDrive. Based on Madrone’s invention, it consists of flexible slots (shown above) enclosed in a metal case with a slot in the east and one in the west. When the gaps are pressurized to different levels, one side expands and tilts the solar structure in the opposite direction. The AirDrive X actuators of the Sunfolding system weigh less than 50 kilograms. Vice President of Sales and Strategic Partnerships Wes Fuller said pv-lehti USA that two people can lift them and attach them to posts anchored to the ground. Automotive pneumatic wiring harnesses are connected to the supply air system – one for every 5 MW. These systems are delivered pre-assembled and can be dropped into place on site.

According to Sunfolding, the pneumatic system has fewer critical points of failure than traditional mechanical systems, which dramatically reduces maintenance costs. AirDrive X actuators use advanced polymers supplied by DuPont to help them withstand the weather of wind, heat, rain and snow.

Sunfolding’s first product was the T29 tracking device, which reportedly changed the tracking environment with the help of pneumatics. It will be installed at 39 projects in 12 states, including sites in California, Colorado, Georgia, Pennsylvania and Texas.

Introduced in September 2022, TopoTrack is designed for variable terrain. Like the T29, it uses AirDrive technology, but with mechanically independent, scaled-down tracking rows.

The company reports that TopoTrack’s rows are 10 times shorter than traditional trackers and can provide 20 degrees of variation between trackers, improving slope tolerance between rows and allowing articulation in terrain, including a complete change of direction in terrain if needed.

The design uses two posts, two actuators and two purlins. Due to the tracker’s flexibility and simplicity, Sunfolding says the tracker’s footprint in the project area can increase as the distance between the trackers is reduced. Fuller noted that TopoTrack can reduce the need for grading by an estimated 97%, resulting in additional savings.

Headquartered in Alameda, California, Sunfolding’s poles, actuators and purlins are manufactured in the USA. The company partners with automotive component suppliers to manufacture the AirDrive and reports that 90% of its bill of materials is sourced within a 250-mile radius. The production facility located in the Midwest enables short delivery times and reduces procurement risks.

TopoTrack was recently deployed in a location with strict environmental protection measures. This site had complex terrain in a high snowpack area. TopoTrack technology is said to allow the client to zero-rate on this site, greatly minimizing the cost of handling complex terrain and allowing for risk.

David is a passionate writer and researcher who specializes in solar energy. He has a strong background in engineering and environmental science, which gives him a deep understanding of the science behind solar power and its benefits. David writes about the latest developments in solar technology and provides practical advice for homeowners and businesses who are interested in switching to solar.

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