A plug-n-play modular, mobile building block

Contractors build today's permanent solar farms using sophisticated tools like GPS guided lasers, but their assembly methods are crude and ignore the mass customization that has advanced other industries. TrackerSled's pre-engineering, prefabrication, and plug-n-play modularity will surpass current technology while simplifying solar development for rural electrical cooperatives. Most important, TrackerSled is agnostic to topography and underground conditions, vastly increasing the amount of land available for solar farms.

Instead of manually constructing solar farms from tens of thousands of pieces on-site after precisely driving posts into surveyed land, crews will build TrackerSleds from 16 prefabricated assemblies in a common staging area accessible to semis and served by support facilities. In an environmentally-controlled shed off-site, teams will prefabricate 90 percent of a TrackerSled, including the skis, lateral trusses, posts, and multiple PV modules premounted to sections of torque tubes.

Each TrackerSled's chassis will rest on two ballasted skis, spaced about twenty feet apart in parallel. On-site, crews will ballast the tanks with crushed rock or treated water. In the future, electric co-ops may choose to install batteries instead. Teams will assemble the chassis from box trusses that span between and above the skis, providing a broad base to resist overturning at a fraction of the cost of a driven pile. Box trusses will nest with the skis, along with the vertical posts, on flatbed trailers to minimize cubic volume for transportation. The vertical posts will support torque tube bearings at the middle and end of each ski. 

Other semi-trailers outfitted with custom racks will transport TrackerSled-long sections of PV modules premounted to torque tubes. Pre-engineering and preassembling these components is more cost effective  over the piece by piece method used by EPC vendors today. Once dropped into the bearings on-site with the aid of a crane, each section of modules will rotate 120-degrees during a summer day.

TrackerSled simplifies on-site logistics. Every acre of TrackerSled farm requires only eight semi deliveries to a single staging location. Aided by a truck-mounted crane, a four-person crew will assemble a TrackerSled in one hour. Afterward, a tractor will tow TrackerSleds to their inaugural position, where a companion tractor will assist with final connections.  Since assembling and towing operations occur in parallel, a twenty-four person crew can place twelve acres of sleds in two workweeks, while a separate electrical BOS (Balance of System) crew works in parallel to construct its permanent infrastructure. 

Instead of taking six months to a year to construct a traditional solar farm, TrackerSled crews will build them in weeks. By default, crews will arrange TrackerSleds in 250-foot long columns of five sleds, with a drive sled in the middle. On that TrackerSled, a pair of slew drives, powered by dedicated PV modules, will rotate the torque tubes of an entire column, reorienting thirty-three 45vdc PV modules on each side that comprise a full 1,500vdc string.

Like current trackers, sensors onboard each string of PV modules will signal a controller that will orient the modules to maximize energy harvest. Aided by machine learning, the controller will react during suboptimal solar conditions (i.e., overcast skies) to maximize yield.

Unlike current trackers that require level land, crews can place TrackerSleds on a rolling terrain, linking them together with torque tube connectors resembling the power take-off (PTO) drive shafts of row crop tractors. These connectors accommodate misalignments along all three axes, something most trackers cannot do.

In addition to saving time, electric co-ops can deploy TrackerSleds to save money. A completed 25-foot x 50-foot TrackerSled towed to initial position on a farm will cost approximately $18,000, including $3,600 for local labor. An electrical co-op can install a 12-acre field of TrackerSleds for an estimated cost of $2 per watt, comparing favorably to similarly-sized distributed scale solar farms. In addition to their modest production cost, TrackerSleds obviate soft costs for extensive surveys, civil engineering fees, steep property tax increases, and environmental impact studies.

Electric co-ops can support their rancher members, too, while encouraging them to work with row crop farmers. Ranchers can choose to graze their animals on the cover crops of row crop farmers or plant mixes on their land that double as forage for livestock. Animals integrate well with regenerative practices. Ranchers deploy TrackerSleds like row crop farmers or arrange them in a checkerboard spanning across two adjacent fields. In either case, the spaces between the TrackerSleds become de facto paddocks for high-density rotational grazing, saving the rancher copious amounts of labor. They only need to provide water and portable fencing at the open ends. 

With twelve acres of TrackerSleds supporting daily rotations, each paddock will have 58 days to recover, which is ideal. Depending on the rancher's chosen stocking density, each paddock will support between 14 and 215 head of cattle per day.  

When a rural electric cooperative pays its farmer members to generate electricity with TrackerSleds on dual-use farm fields, benefits accrue to the entire community. Farmers will have the financial headroom to conduct multi-year regenerative trials on prime farmland, while every co-op member will save on their electric bill.  Distribution co-ops will proactively develop front-of-the-meter Distributed Energy Resources themselves, connected to smart inverters that will allow them to monitor the two-way grid.  TrackerSled will license regional fabricators to build TrackerSleds on area farms served by the rural electric cooperative.