American researchers propose the use of steel zippers to attach solar modules to fences on animal farms as a low-cost shelving solution for agricultural electrical applications. They found that the proposed approach is technically and economically viable, provided careful wind load tests are carried out on the fences.
“This is perhaps the least expensive way to put it on the shelves,” study lead author Joshua M. Pearce said. pv magazine. “We showed that at least one solar module between two vertical posts is mechanically acceptable for all conventional farm enclosures. In this case, the rack is almost free.”
The researchers identified three main fence typologies: fences based on multiple battens placed between main posts to support the fence wire; fences using posts to which fence wires or netting are attached; and fences utilizing various types of pre-fabricated netting to suit the need and sometimes the aesthetic. “Typically, fences mainly use high-tensile steel wire and light steel wire,” they noted. “Their diameters are usually 4mm, 3.15mm and 2.5mm for high tensile (HT) wire and mild steel wire respectively.”
To determine whether an existing fence can be used for solar energy, developers must first determine whether the fence can withstand a certain wind load in a specific location by adding solar panels, as well as the topological, geographic, and climatic challenges of the area. . In this regard, the group stated that special attention should be paid to the size and spacing of the line post and added that the most important factors to be carefully considered are the height of the fence, the depth of the base, the design and size of the mesh fabric, and the strength of the material of the posts.
The researchers also explained that wind load measurements should be made using the Main Wind Force Resisting System (MWFRS) and Components & Cladding (C&C) procedures, as well as the Open Source Wind Load Calculator tool used to calculate the wind. load on a fence in a certain area of the United States. “The program prints wind loads as base shear force in pound-force (lbf) and base moment in foot-pound force (ft-lbf),” they elaborated, adding that they calculated wind loads ranging from 80 mph. 150 mph (129 km/h – 241 km/h).
The academics conducted a series of field tests using three Cheetah HC 72 M monocrystalline PERC panels manufactured by China-based JinkoSolar. They said two people completed the installation quickly, with one module requiring seven minutes and a total of four zips to install.
They also ran a series of simulations to retrofit existing farm fencing to a variety of farms, including sheep, goats, pigs, cows, and alpacas, and found that solar projects based on the proposed approach would be economically viable in the United States.
“The cost of retrofitting the rack is just the cost of four stainless steel zippers per module, which can be purchased in packs of 120 for $11 or about 37 cents per module,” they explained. “With modules ranging from 250 to 500 W, the off-the-shelf cost of an existing enclosure is less than a penny per watt.”
Pearce said the research team also determined what would be the optimal inverter strategy depending on how much energy a farmer needs. “Small farmers can use the free e-book to design the system, install it themselves with metal zip ties, and then just call in an electrician to hook it up,” he concluded.
The scientists presented their findings in the journal “The possibility of using enclosures as low-cost solar power racks,” published Solar energy. “Future work is necessary to determine the global utility of this vertical solar fence approach,” they said, pending how the proposed method can be improved.
The research group consists of researchers from Western University in Canada and Michigan Technological University in the United States.